WO2001094991A1

WO2001094991A1 - Composite light dispersion for compensating device and method for compensating light dispersion using the device

Info

Publication number: WO2001094991A1
Application number: PCT/JP2001/004852
Authority: WO
Inventors: Kazuro Kikuchi; Yuichi Takushima; Mark Kenneth Jablonski; Yuichi Tanaka; Haruki Kataoka; Kenji Furuki; Noboru Higashi; Kazunari Sato; Hiroshi Yaguchi; Shiro Yamashita; Hironori Tokita
Original assignee: Oyokoden Lab Co., Ltd.
Priority date: 2000-06-08
Filing date: 2001-06-08
Publication date: 2001-12-13
Also published as: AU2001264226A1

Abstract

In conventional optical communication at a communication bit rate of 10 Gbps or above, especially 40 Gbps or above, wavelength dispersion takes place in a signal propagated through an optical fiber to cause a significant problem in communication. A composite light dispersion compensating device of the invention comprises a light dispersion compensating element where a reflector or a mutilayer film element is opposed to the incident face of a mutilayer film element which can compensate dispersion utilizing group velocity delay time-to-wavelength characteristics. A light dispersion compensating device having a group velocity delay time-to-wavelength characteristic curve having a wide bandwidth and a large extreme value of the group velocity delay time can be also realized by connecting a plurality of dispersion compensating elements in series. Dispersion can be compensated for each channel or a plurality of channels.

Description

Description Composite optical dispersion compensating element and optical dispersion compensating method using the element

In the following description of the present invention, the optical dispersion compensation is simply referred to as dispersion compensation, the optical dispersion compensation element is simply referred to as dispersion compensation element, and the optical dispersion compensation method is also simply referred to as dispersion compensation method. In addition, the composite type optical dispersion compensating element that is the dispersion compensating element of the present invention may be simply referred to as an optical dispersion compensating element or a dispersion compensating element. The present invention relates to an optical communication using an optical fiber (hereinafter, also referred to simply as a fiber) for a transmission line and using, for example, light having a wavelength of about 1.55 m as signal light. An element capable of compensating for the resulting second or higher order chromatic dispersion (hereinafter simply referred to as dispersion) (hereinafter, an element capable of compensating the secondary dispersion is an element capable of changing the secondary dispersion, Similarly, an element capable of compensating for a third-order dispersion, which will be described later, is also an element capable of changing a third-order dispersion, or a third-order dispersion compensating element. At least one pair of dispersion compensating elements having the light incident surfaces facing each other, a low-loss, composite light dispersion compensating element, and an element having the same configuration as described above are used. Dispersion compensation Law on.

A notable feature of the present invention is that a composite dispersion compensating element and a dispersion compensating method using the same as described below, which can compensate for the third-order dispersion with low loss, or A dispersion compensating element capable of performing second and third order dispersion compensation and a dispersion compensating method using the same.

The composite dispersion compensating element of the present invention may include only the third-order dispersion compensating element, and is configured to perform not only the third-order dispersion compensation but also the second-order dispersion compensation. In some cases, it may include a means for changing the incident position of incident light on the incident surface, which will be described later.In some cases, it may be mounted on a case, and may be a so-called chip or wafer not mounted on the case. It may be in the form of a letter.

The dispersion compensating element of the present invention includes all of these forms. It can take various forms depending on the purpose of selling.

In the present invention, the second-order dispersion compensation means “compensating for the slope of the temporal wavelength characteristic curve described later with reference to FIG. 12A”, and the third-order dispersion compensation refers to “FIG. Is used to compensate for the bending of the wavelength-time characteristic curve described later. " Background art

In optical communications that use optical fibers for communication transmission lines, there is a need for longer-distance communication transmission lines and higher-speed communication bit rates, along with advances in use technology and expansion of the range of use. In such an environment, dispersion generated when transmitting an optical fiber becomes a serious problem, and various attempts have been made to compensate for dispersion. Until now, second-order dispersion has been a major problem, and various compensations have been proposed, some of which have been effective.

However, as the demands on optical communication become more sophisticated, compensating for second-order dispersion alone during transmission is not sufficient, and compensating for third-order dispersion is becoming a serious issue. Hereinafter, a conventional second-order dispersion compensation method will be described with reference to FIGS. 12A to 12C and FIG.

Figure 13 is a diagram illustrating the dispersion-wavelength characteristics of a single-mode optical fiber (hereinafter, also referred to as SMF), a dispersion compensating fiber, and a dispersion-shifted fiber (hereinafter, also referred to as DSF). In FIG. 13, reference numeral 601 is a graph showing the dispersion-wavelength characteristic of the SMF, 602 is a graph showing the dispersion-wavelength characteristic of the dispersion fiber, and 603 is a graph showing the dispersion-wavelength characteristic of the DSF. Is a graph in which wavelength is plotted on the horizontal axis.

As is clear from Fig. 13, in the SMF, the dispersion increases as the wavelength of the light input to the fiber (hereinafter also referred to as “incident”) increases from 1.3 μπι to 1.8 μπι. In a fiber, the dispersion decreases as the wavelength of the input light (hereinafter also referred to as the incident light) increases from 1.3 111 to 1.8 μπι. In the DSF, the dispersion decreases as the wavelength of the input light increases from 1.2 111 to about 1.55 μπι, and the wavelength of the input light increases from about 1.55 ^ 111 to 1.8 μπι. Dispersion increases as it becomes. And DSF uses the conventional 2.5 Gb ps (2.5 Gb / s In optical communications of Tsu g) about communication bit rate, the wavelength of the input light is 1. 'in the vicinity of 55 _w πι, dispersion does not occur on the trouble optical communication.

12A to 12C are diagrams mainly illustrating a second-order dispersion compensation method.FIG. 12A shows a wavelength-time characteristic and a light intensity-time characteristic, and FIG. 12B shows a transmission line using an SMF. FIG. 12C is a diagram illustrating a transmission example in which a second-order dispersion compensation is performed using a dispersion compensating fiber, and FIG.

In FIGS. 12A to 12C, reference numerals 501 and 511 denote graphs showing characteristics of signal light before input to the transmission line, reference numeral 530 denotes a transmission line configured by the SMF 531, and reference numerals 502 and 512 denote graphs. 501 and 511 are graphs showing the characteristics of signal light output from the transmission line 530 after transmission of the signal light having the characteristics shown in the transmission line 530. 520 is a transmission line composed of the dispersion compensation fiber 521 and the SMF 522. , 503 and 513 are graphs showing the characteristics of the signal light output from the transmission line 520 after the signal light having the characteristics shown in the graphs 501 and 511 is transmitted through the transmission line 520. Reference numerals 504 and 514 represent the case where the signal light having the characteristics shown in the graphs 501 and 511 is transmitted through the transmission line 520 and output from the transmission line 520, and the desired third-order dispersion compensation described below is performed by the present invention. It is a graph which shows the characteristic of signal light, and is almost in agreement with graphs 501 and 511. Graphs 501, 502, 503, and 504 are graphs in which the vertical axis is wavelength and the horizontal axis is time (or time), respectively, and graphs 511, 512, 513, and 514 are light intensity on the vertical axis, respectively. , A graph with the horizontal axis representing time (or time). Reference numerals 524 and 534 are transmitters, and 525 and 535 are receivers.

As described above, the conventional SMF increases the dispersion as the wavelength of the signal light increases from 1.3 μπι to 1.8, so that in high-speed communication and long-distance transmission, the group velocity delay due to dispersion increases. Is generated. In the transmission path 530 constituted by the SMF, the signal light is greatly delayed on the long wavelength side compared to the short wavelength side during transmission, as shown in graphs 502 and 512. For example, in high-speed communication and long-distance transmission, the changed signal light may not be able to be distinguished from the preceding and succeeding signal lights, and may not be received as an accurate signal.

Conventionally, to solve such a problem, for example, as shown in FIG. The dispersion is compensated (or called correction) using a dispersion compensating fiber.

The conventional dispersion compensating fiber solves the SMF problem that the dispersion increases as the wavelength increases from 1.3 μπι to 1.8 μπι. The dispersion is designed to decrease as the length increases from 1.3 111 to 1.8 μπι.

The dispersion compensating fiber can be used, for example, by connecting the dispersion compensating fiber 521 to the SMF 522 as shown by the transmission line 520 in FIG. In the above transmission line 520, the signal light is greatly delayed on the long wavelength side in the SMF 522 compared with the short wavelength side, and is significantly delayed in the dispersion compensation fiber 521 on the short wavelength side compared to the long wavelength side. As a result, as shown in the graphs 503 and 513, the amount of change can be suppressed smaller than the changes shown in the graphs 502 and 512.

However, in the above-mentioned conventional method of compensating for the second-order chromatic dispersion using the dispersion compensating fiber, the chromatic dispersion of the signal light transmitted through the transmission line is represented by the state of the signal light before input to the transmission line, that is, as shown in FIG. It is not possible to compensate for dispersion up to the form of 01, but the limit is to compensate for the form of Darraf 503. As shown in graph 503, in the conventional second-order chromatic dispersion compensation method using a dispersion compensation fiber, the light of the central wavelength of the signal light is compared with the light of the short wavelength side and the light of the long wavelength side. Without delay, only the light of the component on the shorter wavelength side or longer wavelength side than the light of the central wavelength component of the signal light is delayed. Then, as shown in the graph 513, a ripple may be generated in a part of the graph.

These phenomena are becoming serious problems such as the inability to receive accurate signals as the need for longer transmission distances and higher communication speeds increases in optical communications. For example, in a high-speed communication that transmits 10,000 km at a communication bit rate of 40 Gbps (40 gigabits per second) and a high-speed communication that transmits a distance of the order of 1,000 km at 80 Gbps, these phenomena occur. It is of great concern and of great concern. In such high-speed communication and long-distance communication, it is considered difficult to use the conventional optical fiber communication system. For example, it is necessary to change the material of the optical fiber itself. It is also a serious problem from the economic viewpoint of system construction.

It is difficult to perform such dispersion compensation only with second-order dispersion compensation. Dispersion compensation is required.

Conventionally, there is a DSF as an optical fiber that reduces the second-order dispersion for light with a wavelength of around 1.55 in, but this fiber also has the characteristics shown in Figs. 12A and 13 above. Obviously, the third-order dispersion compensation, which is the subject of the present invention, cannot be performed. In realizing high-speed and long-distance optical communications, third-order dispersion is increasingly recognized as a major problem, and compensation for it is becoming an important issue. Many attempts have been made to solve the third-order dispersion compensation problem, but a third-order dispersion compensator or compensation method that can sufficiently solve the conventional problems has not yet been put into practical use.

An example using a fiber formed with a diffraction grating as a method of compensating for third-order dispersion has been reported, but it has fatal disadvantages such as the inability to perform the necessary compensation, large loss, and large dimensions. In addition, the price is high and practical application is not expected. As an example of the above-described third-order dispersion compensation, the present inventors succeeded in a certain degree of third-order dispersion compensation using a small-sized optical dispersion compensation element using a multilayer film such as a dielectric, and We have made great progress in communication technology.

For example, when the communication bit rate is increased to 40 Gbps, 80 Gbps, etc., the third-order dispersion compensation is ideally performed, or the third-order dispersion compensation in multi-channel optical communication is performed. In order to sufficiently compensate for dispersion, a dispersion compensating element or dispersion compensating method capable of sufficiently compensating for second and third order dispersion in a wider wavelength range is desired.

As one proposal, a third-order dispersion compensator capable of adjusting the wavelength band of group velocity delay and the delay time of group velocity delay was proposed. In particular, we proposed a wavelength-tunable dispersion compensator (that is, selectable wavelengths for dispersion compensation) as one of the inexpensive ways to commercialize a third-order dispersion compensator suitable for the wavelength of each channel.

However, it is quite difficult to obtain a dispersion compensating element having a group velocity delay time-one wavelength characteristic that can sufficiently perform dispersion compensation in a wide wavelength range with these dispersion compensating elements.

As a method of obtaining a dispersion compensating element having a group velocity delay time-one wavelength characteristic that can perform good dispersion compensation in a wide wavelength range, an element capable of performing dispersion compensation proposed by the present inventors is called a signal light. There is a method of connecting a plurality of optical paths in series. this In this case, if an element capable of performing dispersion compensation is connected in series via an optical fiber collimator having an optical fiber and a lens, for example, the overall shape and dimensions of the dispersion compensation element become large, and the loss Are integrated. Therefore, depending on the usage conditions of the dispersion compensator, it is a major problem how the loss of the dispersion compensator can be reduced.

When a plurality of elements capable of performing dispersion compensation are connected in series in an optical path to form a light dispersion compensation element that can be used in a wide wavelength band such as 30 nm, for example, It is desired to realize a method of constructing a dispersion compensating element that is small, has low loss, and is easy to connect.

The present invention has been made in view of such a point, and an object of the present invention is to perform sufficient dispersion compensation, especially third-order dispersion compensation, over a wide wavelength range that has not been practically used in the past. To provide an optical dispersion compensator with excellent group velocity delay time vs. wavelength characteristics that can be used in a compact, easy-to-use, low-loss, high-reliability, and suitable for mass production, at low cost. In addition, a dispersion compensating element and a dispersion compensating method that enable a third-order dispersion compensation using a multilayer film element having a function of adjusting the wavelength band of the group velocity delay and the delay time. A dispersion compensating element and a dispersion compensating method capable of performing the following dispersion compensation are provided. Disclosure of the invention

The present invention relates to a composite dispersion compensating element, and also relates to a dispersion compensating method for compensating dispersion by constructing a dispersion compensating element substantially equivalent to the composite type dispersion compensating element of the present invention. Therefore, in the following description, the content of the dispersion compensation element of the present invention will be described as the dispersion compensation element used in the dispersion compensation method of the present invention, and will also serve as the description of the dispersion compensation method.

The greatest feature of the composite dispersion compensation element used in the dispersion compensation method of the present invention is that a plurality of elements capable of performing third-order dispersion compensation using a multilayer film, or an element capable of performing dispersion compensation (Hereinafter referred to as the element that can perform dispersion compensation and the element that can perform dispersion compensation) ), Which are connected in series with very low loss along the optical path of the signal light. The composite type dispersion compensating element can be formed so as to perform not only the third-order dispersion compensation but also the second-order dispersion compensation. In order to achieve the object of the present invention, in the optical dispersion compensating element used in the optical dispersion compensating method of the present invention, the element capable of performing the dispersion compensation uses a group velocity delay time-wavelength characteristic of a multilayer film. This is an optical dispersion compensating element that can perform dispersion compensation. When performing third-order dispersion compensation, the group velocity delay time-one wavelength characteristic curve of the multilayer film is formed so as to have at least one extreme value in the wavelength band in or near the dispersion compensation target wavelength band. It is characterized by the group velocity delay time-wavelength characteristic curve of the composite type optical dispersion compensating element used in the optical dispersion compensating method of the present invention and the optical dispersion compensating element used in the optical dispersion compensating method of the present invention. The group velocity delay time-wavelength characteristic curve of an element capable of performing each dispersion compensation usually has a different shape.

The composite type optical dispersion compensating element of the present invention having the multilayer film can basically be applied to any wavelength range. The present invention relates to a composite type optical dispersion compensation element using a multilayer film having a group velocity delay time-one wavelength characteristic curve having at least one extreme value in a wavelength range of 1260 to 1700 nm which is currently being watched. A great effect can be achieved by using.

More specifically, according to the present invention, the 0-band (1260-1360 nm), the E-band (1360-1460 nm), the S-band (1460_1530 nm), the C-band (1 530—1 565 η m), L-band (1 565—1625 nm), and U—band (1 625—1675 nm) Alternatively, a composite dispersion compensator using a multilayer film having a group velocity delay time-one wavelength characteristic curve having at least one extreme value in a specific wavelength range within one wavelength band can be configured. Thus, accurate dispersion compensation can be performed in each communication wavelength range.

In order to achieve the object of the present invention, a composite type optical dispersion compensating element of the present invention is an optical dispersion compensating element capable of compensating for dispersion as chromatic dispersion by using an optical fiber for communication using a communication transmission line. A composite type optical dispersion compensating element combining: In the combined type optical dispersion compensating element, at least a part of the optical dispersion compensating elements constituting the optical dispersion compensating element has at least a part of a light incident surface on at least a part of the optical dispersion compensating elements. It is characterized in that a light-entering surface of a light-dispersion compensating element, which is different from the light-dispersion compensating element, or a reflecting surface of a reflector, which is also referred to as a reflector A below, is disposed oppositely. .

Further, an example of the composite type optical dispersion compensating element of the present invention includes at least a pair of the optical dispersion compensating elements which are arranged opposite to each other among the optical dispersion compensating elements constituting the composite type optical dispersion compensating element. The light incident surface of one of the light dispersion compensating elements and the light incident surface of the other light dispersion compensating element, or the light incident surface of the opposing light dispersion compensating element and the reflection of the reflector A Between the incident surface of one of the optical dispersion compensating elements and the incident surface of the other optical dispersion compensating element, or It is arranged between the incident surface of the element and the reflecting surface of the reflector A so close that the light incident on the light dispersion compensating element can be incident and reflected several times. It is characterized by having.

In order to achieve the objects of the present invention, examples of the present invention each have some features. These are illustrated below.

Further, an example of the compound type optical dispersion compensation element of the present invention is characterized in that there are a plurality of connection methods or connection paths of the plurality of elements capable of performing dispersion compensation.

An example of the compound type optical dispersion compensating element of the present invention is characterized in that a connection method or a connection path of the plurality of elements capable of performing dispersion compensation can be selected from outside the optical dispersion compensating element.

An example of the composite type optical dispersion compensating element of the present invention is a means for selecting a connection method or a connection path of the plurality of elements capable of performing dispersion compensation from outside the optical dispersion compensating element. It is characterized by:

An example of the composite type optical dispersion compensating element of the present invention is an element in which at least a part of the optical type dispersion compensating element constituting the composite type optical dispersion compensating element uses a multilayer film capable of compensating dispersion. It is characterized in that it is a light dispersion compensation element having a so-called multilayer film element. An example of the composite type optical dispersion compensating element of the present invention is a composite type optical dispersion compensating element, which faces at least a part of the light incident surface constituting the composite type optical dispersion compensating element. A light dispersion compensating element having a so-called multi-layer film element in which the light dispersion compensating element on which the incident surface of the compensating element or the reflecting surface of the reflector A is arranged is a device using a multilayer film capable of compensating for dispersion. It is characterized by being.

An example of the composite type optical dispersion compensating element of the present invention is a composite type optical dispersion compensating element, which faces at least a part of the light incident surface constituting the composite type optical dispersion compensating element. The light incident surface of the compensating element or the light dispersion surface on which the reflecting surface of the reflector A is disposed, and the light incident surface of the light compensating element and the incident surface or the reflection of the another light dispersion compensating element disposed opposite thereto. One or both of the reflection surfaces of the body A are flat.

An example of the composite type optical dispersion compensating element of the present invention is a composite type optical dispersion compensating element, which faces at least a part of the light incident surface constituting the composite type optical dispersion compensating element. The light incident surface of the compensating element or the light scattering surface on which the reflecting surface of the reflector A is disposed, and the light incident surface of the light of the compensating element and the incident surface of the another light dispersion compensating element disposed opposite thereto; Is characterized in that one or both of the reflection surfaces of the reflector A are curved surfaces.

An example of the composite type optical dispersion compensating element of the present invention is a multilayer optical element comprising the optical dispersion compensating element, wherein the multilayer film element includes at least three reflective layers, also referred to as a reflective layer, and at least two optically transparent layers. Wherein each of the one light transmission layers is formed so as to be sandwiched between two of the reflection layers, and the multilayer film has a wavelength of incident light; The reflective layer has at least one reflective layer having a reflectance of 99.5% or more with respect to a central wavelength sometimes referred to as a central wavelength, and firstly, as the light proceeds from the incident surface in the thickness direction of the multilayer film. The reflectivity of each of the reflective layers arranged up to the position of the reflective layer where the appearing reflectivity is 99.5% or more becomes larger as the flow proceeds from the incident surface side in the thickness direction of the multilayer film. It is characterized by having.

An example of the composite type optical dispersion compensating element according to the present invention is a method in which at least a part of the light incident surface of the optical dispersion compensating element is opposed to the optical dispersion compensating element, Light dispersion compensating element having a surface or a reflecting surface of the reflector A A reflector or a reflector different from the reflector A, hereinafter referred to as a reflector B, is provided at or near at least a part of the child.

In an example of the composite type optical dispersion compensating element of the present invention, the reflector B may be formed of any one of a pair of optical dispersion compensating elements having an incident surface opposed thereto, or facing the incident surface. The light is output from one of the light dispersion compensating element on which the reflecting surface of the reflector A is disposed and the light reflector A. The light dispersion compensating element or the light reflecting element reflects light referred to as light A. It is characterized by being arranged so that it can be incident on A.

In an example of the composite type light dispersion compensation element of the present invention, the light A is incident as light referred to as reflected light B by the reflector B, but the light dispersion compensating element or the reflected light from which the light A is emitted. It is characterized by being body A.

An example of the compound type optical dispersion compensating element of the present invention is characterized in that the emission position of the light A and the incident position of the light B in the optical dispersion compensation element are different positions. An example of the composite type optical dispersion compensating element of the present invention is characterized in that the light A and the light B are parallel and the traveling directions are opposite.

An example of the composite type optical dispersion compensating element of the present invention is characterized in that the reflector B has at least three reflecting surfaces.

An example of the composite type optical dispersion compensating element of the present invention is characterized in that at least one reflecting surface of the reflector B is movable.

An example of the composite type optical dispersion compensating element of the present invention is characterized in that the means for driving the movable reflecting surface of the reflector B is a manual means or an electric means. An example of the composite type optical dispersion compensating element of the present invention is such that each of the reflectors B is also referred to as each optical dispersion compensating element alone of a pair of optical dispersion compensating elements in which the incident surfaces are opposed to each other. It is possible to reflect the light emitted from any one of the elements or the light emitted from either the reflecting surface of the reflector A and the incident surface of the optical dispersion compensating element which are arranged to face each other. At least one pair of the light dispersion compensating element or the light dispersion compensating element and the light dispersion compensating element in which the incident surfaces are disposed to face each other are provided at the same end of the reflector A. A pair of light beams whose incident surfaces are arranged to face each other It is characterized in that it is provided integrally on at least one of the dispersion compensating elements or on at least one of the optical dispersion compensating element and the reflector A arranged to face each other.

An example of the composite type optical dispersion compensating element of the present invention is characterized in that the reflector B is a corner cube.

Examples of the composite type optical dispersion compensating element of the present invention include any one of a pair of optical dispersion compensating elements in which the light B is disposed with the incident surface facing each other, or The direction in which the light is incident on one of the dispersion compensating element and the reflector A and travels later is parallel to the traveling direction traveling in the light dispersion compensating element before the light A exits, and in the opposite direction. It is characterized by having.

Examples of the composite type optical dispersion compensating element of the present invention include: an end portion of a pair of optical dispersion compensating elements in which the incident surfaces are arranged opposing each other; or an optical dispersion compensating element arranged in opposition. And a reflector B is provided at a plurality of locations at the end of the reflector A.

Examples of the composite type optical dispersion compensating element of the present invention include: the incident surface of each of the individual optical dispersion compensating elements of the pair of optical dispersion compensating elements arranged to face each other; or the reflector A. At a position where the traveling direction of the signal light that is incident on the incident surface of the optical dispersion compensating element arranged oppositely and travels while undergoing dispersion compensation moves from one side of the incident surface to the other side, It is characterized by being in the opposite direction in turn.

An example of the composite type optical dispersion compensating element of the present invention is a multilayer film element in which each optical dispersion compensating element alone of a pair of optical dispersion compensating elements having the incident surfaces facing each other is formed on different substrates. A composite type optical dispersion compensating element characterized by comprising: In an example of the composite type optical dispersion compensating element of the present invention, each of the optical dispersion compensating elements alone of at least a pair of the optical dispersion compensating elements whose incident surfaces are opposed to each other transmits incident light. It is characterized in that the incident surfaces are formed on the surfaces of the same substrate which are opposed to each other so that the incident surface is on the substrate side.

An example of the composite type optical dispersion compensating element of the present invention is that the reflectance of at least three reflective layers from the substrate side of a multilayer film constituting at least one of the optical dispersion compensating element and each of the optical dispersion compensating elements alone is The closer to the substrate, the farther from the reflective layer, the closer to the reflective layer. It is characterized by being large.

Examples of the composite type optical dispersion compensating element of the present invention include: a pair of optical dispersion compensating elements in which at least one pair of the incident surfaces are arranged to face each other; or an incident surface of the optical dispersion compensating element and a reflector A The incident position and the outgoing position of the signal light of the light dispersion compensation element in which the reflection surfaces of the light dispersion compensation elements are opposed to each other are the same as those of the pair of light dispersion compensation elements in which the incidence surfaces are opposed to each other, or It is characterized by being on a different side of the optical dispersion compensating element arranged opposite to A.

Examples of the composite type optical dispersion compensating element of the present invention include: a pair of optical dispersion compensating elements in which at least one pair of the incident surfaces are arranged to face each other; or an incident surface of the optical dispersion compensating element and a reflector A The incident position and the outgoing position of the signal light of the optical dispersion compensating element in which the reflecting surfaces of the optical dispersion compensating elements are opposed to each other are the same. It is characterized by being on the same side of the optical dispersion compensating element that is disposed opposite to the above.

An example of the composite type optical dispersion compensating element of the present invention is that at least one of the multilayer film elements has at least five kinds of laminated films having different optical properties, that is, optical properties such as light reflectance and film thickness. A multi-layer film having at least five different laminated films, wherein the multi-layer film has at least three types of reflective layers including at least two types of reflective layers having different light reflectances from each other; It has at least two light transmission layers in addition to the reflection layer, wherein each one of the three types of reflection layers and each one of the two light transmission layers are alternately arranged, and the multilayer film is In order from one side in the thickness direction of the film, a first layer as a first reflection layer, a second layer as a first light transmission layer, a third layer as a second reflection layer, and a second light transmission It is composed of a fourth layer, which is a layer, and a fifth layer, which is a third reflective layer. In the first to fifth layers, the optical path length, that is, the film thickness of each layer constituting the multilayer film when considered as the optical path length with respect to the central wavelength of the incident light is The film thickness has a value in the range of approximately 1%, which is approximately an integral multiple of λ / 4, and the multilayer film is a layer having a higher refractive index of 1/4 times ± 1% of the film thickness. It is composed of a plurality of layers combining the layer 層 and the layer L having a lower refractive index with a thickness of about% times ± 1% of λ and a thickness of about λ.

The multilayer film Α, the five-layer laminated film, that is, the first to fifth layers, the thickness of the multilayer film The first layer composed of three sets of HL layers, which are layers combined one by one in the order of layer H and layer L, in order from one side in the direction of movement, and a layer combining layer H and layer H The second layer is formed by laminating 10 sets of HH layers, the third layer is formed by laminating 1 layer L and 7 sets of HL layers, and 38 sets of HH layers A fourth layer composed of laminated layers, a layer L composed of a fifth layer composed of one layer L and a fifth layer composed of 13 sets of HL layers,

Instead of the second layer, which is formed by laminating 10 sets of HH layers of the multilayer film A, the second layer is a multilayer film having the same direction as that of the multilayer film A. In order from one side in the thickness direction, 3 sets of HH layers, 3 sets of LL layers, which is a layer combining layers L and L, 3 sets of HH layers, 2 sets of LL layers, and 2 sets of HH layers One set of layers is a multilayer film formed of a laminated film formed by laminating in this order, and a multilayer film C is formed by laminating 38 sets of HH layers of the multilayer film A or B. Instead of the fourth layer, the fourth layer is, in order from one side in the thickness direction of the film in the same direction as that of the multilayer film A, three sets of HH layers, three sets of LL layers, and three sets of HH layers. 3 sets of layers, 3 sets of LL layers, 3 sets of HH layers, 3 sets of LL layers, 3 sets of HH layers, 3 sets of LL layers, 3 sets of HH layers, 3 sets of HH layers, 3 sets of LL layers, 3 sets of HH layers, 3 sets of LL layers, 3 sets of HH layers, 3 sets of LL layers, 2 sets of HH layers are stacked in this order It is a multilayer film composed of a multilayer film,

The multilayer film D is a layer obtained by combining the five-layered film, that is, the first to fifth layers, in order from one side in the thickness direction of the multilayer film, and combining the layers one by one in the order of layer H. The first layer composed of 5 sets of LH layers, the second layer composed of 7 sets of LL layers, 1 layer H and 7 sets of LH layers The third layer is composed of 5 layers, composed of 57 sets of LL layers, the 5th layer composed of 1 layer of H and 13 sets of-layers of LH The multilayer film E is defined as: a multilayer film E, wherein the five-layer laminated film, that is, the first to fifth layers, are arranged such that two layers of HL are sequentially arranged from one side in the thickness direction of the multilayer film. The first layer is formed by stacking sets, the second layer is formed by stacking 14 sets of HH layers, and the second layer is formed by stacking 1 set of layer L and 6 sets of HL layers. 3 layers, HH layers 24 sets The constituted by a layer Four layers, one layer L and five layers of HL are laminated as a fifth layer composed of 13 sets,

Instead of the second layer formed by laminating 14 sets of the HH layers of the multilayer film E with the multilayer film F, the second layer has a film thickness in the same direction as that of the multilayer film E. In order from one side of the direction, 3 sets of HH layers, 3 sets of LL layers, 3 sets of HH layers, 3 sets of LL layers, 3 sets of HH layers, 2 sets of LL layers, 1 set of LL layers, A set of HH layers is a multilayer film formed of a laminated film formed by laminating one set in this order,

Instead of the fourth layer formed by laminating 24 sets of the HH layers of the multilayer film E or F, the fourth layer is a film in the same direction as the multilayer film E. 3 sets of HH layers, 3 sets of LL layers, 3 sets of HH layers, 3 sets of LL layers, 3 sets of HH layers, 3 sets of LL layers in order from one side in the thickness direction of Set, 3 sets of HH layers, 3 sets of LL layers, 2 sets of HH layers, 1 set of LL layers, 1 set of HH layers It is a multilayer film that has been

The multilayer film H is formed by laminating four sets of layers L and LH in order of the five-layer laminated film, that is, the first to fifth layers, from one side in the thickness direction of the multilayer film. The first layer, the second layer composed of 9 sets of LL layers, the third layer composed of 1 layer H and the 6 sets of LH layers, and the 3rd layer composed of 6 layers of LH layers When a multilayer film composed of a fourth layer composed of set laminations, a fifth layer composed of one layer H, and a fifth layer composed of 13 sets of LH layers,

At least one of the multilayer devices has at least one of the multilayer films A to H.

In an example of the composite type optical dispersion compensating element of the present invention, the film thickness of at least one laminated film constituting the multilayer film of at least one of the optical dispersion compensating elements is parallel to a light incident surface of the multilayer film. It is characterized in that it changes in the in-plane direction of the cross section, that is, in the direction of the incident plane, that is, the film thickness varies depending on the position in the laminated film.

An example of the composite type optical dispersion compensating element of the present invention is a composite type optical dispersion compensating element in which at least a pair of the incident surfaces constituting the composite type optical dispersion compensating element are arranged to face each other. It is characterized in that at least one light transmitting layer of the multilayer film of each light dispersion compensating element alone has a different thickness in different directions.

An example of the composite type optical dispersion compensating element of the present invention is a multilayer film of each optical dispersion compensating element alone of at least a pair of the optical dispersion compensating elements constituting the composite type optical dispersion compensating element. The film thickness of at least one of the light transmitting layers is changed in opposite directions to each other.

Examples of the composite type optical dispersion compensating element of the present invention include adjusting means for engaging with the optical dispersion compensating element and adjusting the film thickness of at least one of the multilayer films, or It is characterized in that means for changing the incident position of light on the incident surface are provided.

An example of the composite type optical dispersion compensating element of the present invention is characterized in that at least one of the multilayer film element elements is an optical dispersion compensating element capable of mainly compensating third-order dispersion.

An example of the composite type optical dispersion compensating element of the present invention is characterized in that at least one of the optical dispersion compensating elements is an optical dispersion compensating element capable of compensating for secondary dispersion.

In order to achieve the object of the present invention, the optical dispersion compensating method of the present invention uses a composite type optical dispersion compensating element having each of the above-mentioned features, or an optical dispersion substantially equivalent thereto. It is characterized by compensating for the dispersion of optical signals by using compensating elements obtained as some parts or the like.

An optical dispersion compensation method according to the present invention is a method for compensating for dispersion as wavelength dispersion in communication using an optical fiber for a communication transmission line, and comprises at least a part of a light incident surface on an optical dispersion compensating element. And an incident surface of a light dispersion compensating element different from the light dispersion compensating element, or a reflecting surface of a reflector which is also referred to as a reflector A below. An optical path of incident light can be formed between the incident surfaces of both the optical dispersion compensating elements, or between the incident surface of the optical dispersion compensating element and the reflecting surface of the reflector A disposed opposite to each other. And the incident light incident between the two incident surfaces or the incident surface and the reflecting surface is incident on the incident surface of the optical dispersion compensating element while traveling along the optical path. Do multiple reflections At least one set comprising composite optical dispersion compensation element configured to allow bets The optical dispersion compensating element of the present invention is characterized in that the incident light travels along this optical path to perform dispersion compensation of the incident light.

An example of the optical dispersion compensation method of the present invention includes: at least one pair of the opposed optical dispersion compensating elements or at least a part or the vicinity of the optical dispersion compensating element and the reflector A, It is characterized in that a reflector or a reflector, also referred to as a reflector B, is arranged below to perform dispersion compensation of incident light.

An example of the optical dispersion compensation method of the present invention is as follows. The reflector B is provided with a pair of light dispersion compensating elements or a light dispersion compensating element arranged opposite to each other and the light output from the reflector A below. It is characterized by arranging so that light, also referred to as A, can be reflected and made incident on the optical dispersion compensating element to perform dispersion compensation of incident light.

An example of the light dispersion compensation method of the present invention is that the light A reflects the light reflected by the reflector B, which is also referred to as light B below, and reenters the light dispersion compensating element from which the light A is emitted. As described above, the invention is characterized in that the light dispersion compensating element and the reflector are arranged to perform dispersion compensation of incident light.

An example of the optical dispersion compensation method according to the present invention is characterized in that the emission position of the light A and the incident position of the light B in the optical dispersion compensation element are different positions.

An example of the optical dispersion compensation method of the present invention is characterized in that the light A and the light B are parallel and the traveling directions are opposite.

An example of the optical dispersion compensation method of the present invention is characterized in that the reflector B has at least three reflecting surfaces.

An example of the optical dispersion compensation method of the present invention is characterized in that the reflector B is a corner cup.

An example of the optical dispersion compensation method according to the present invention is characterized in that at least one of the optical dispersion compensation elements is a multilayer element having a multilayer film capable of performing dispersion compensation.

An example of the optical dispersion compensation method according to the present invention is that the film thickness of at least one laminated film constituting at least one of the multilayer films is an in-plane direction, that is, an in-plane direction in a cross section parallel to a light incident surface of the multilayer film. It is characterized in that it changes in the in-plane direction. An example of the optical dispersion compensating method of the present invention includes: 1260 to 1360 nm, 1360 to 1460 ηm, 1460 to: 1530 ηm, 1530 to 1565 nm, 1565 to 1625 ηm , 1625-: 1675 ηm is characterized by having a group velocity delay time-wavelength characteristic curve having at least one extreme value in at least one wavelength range.

An example of the optical dispersion compensation method according to the present invention is characterized in that a plurality of connection methods of elements capable of performing dispersion compensation in an optical path of signal light can be selected. An example of the optical dispersion compensation method according to the present invention is the optical dispersion compensation method, wherein the dispersion compensation of the signal light is a dispersion compensation capable of performing at least tertiary dispersion compensation.

Although the features of the present invention have been described above, the composite type optical dispersion compensating element and the optical dispersion compensating method of the present invention can be obtained by appropriately combining the inventions having the various features as described above, or using the invention alone. However, as will be described later, the present invention exerts a great effect in ultra-high-speed optical communication such as 4 OGb ps or 80 Gb ps. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram illustrating optical dispersion compensation according to the present invention.

FIG. 2 is a cross-sectional view of the multilayer film of the present invention.

FIG. 3 is a perspective view of the multilayer film of the present invention.

FIG. 4 is a group velocity delay time-wavelength characteristic curve of the multilayer film of the present invention.

FIG. 5A is a graph showing a group velocity delay time-wavelength characteristic of one element capable of performing dispersion compensation, which is a basic element of the dispersion compensation element of the present invention.

FIG. 5B is a diagram illustrating a method of improving the group velocity delay time-wavelength characteristic using a plurality of elements capable of performing dispersion compensation according to the present invention. 5 is a graph showing a group velocity delay time versus wavelength characteristic of the optical dispersion compensating elements of the present invention connected in series.

FIG. 5C is a diagram illustrating a method of improving the group velocity delay time-wavelength characteristic using a plurality of elements capable of performing dispersion compensation according to the present invention. 5 is a graph showing a group velocity delay time versus wavelength characteristic of the optical dispersion compensating elements of the present invention connected in series. FIG. 5D is a diagram for explaining a method of improving the group velocity delay time vs. wavelength characteristic using a plurality of elements capable of performing dispersion compensation according to the present invention. 5 is a graph showing a group velocity delay time versus wavelength characteristic of the optical dispersion compensating elements of the present invention connected in series.

FIG. 6A is a diagram for explaining the connection of the optical dispersion compensating elements, and is a diagram for explaining an example in which two elements capable of performing dispersion compensation are connected in series to constitute an optical dispersion compensating element.

FIG. 6B is a diagram illustrating the connection of the optical dispersion compensating element, and is a diagram illustrating an example in which three elements capable of performing dispersion compensation are connected in series to form an optical dispersion compensating element.

Fig. 6C is a diagram illustrating the connection of the optical dispersion compensating element. In the multilayer film whose film thickness changes in the direction of the incident plane, two signal light incident positions are set along the signal light route. FIG. 3 is a diagram for explaining an example in which the optical dispersion compensating elements are configured by being connected in series in a row.

FIG. 6D is a diagram illustrating an example of the optical dispersion compensating element, and is a diagram illustrating an example in which the optical dispersion compensating element is mounted in one case.

FIG. 7A is a side view illustrating the composite type optical dispersion compensating element of the present invention.

FIG. 7B is a diagram for explaining the composite type optical dispersion compensating element of the present invention, which is viewed from above.

FIG. 8 is a diagram for explaining another example of the composite type optical dispersion compensation element of the present invention. FIG. 9 is a diagram illustrating a group velocity delay time-wavelength characteristic curve of the composite type optical dispersion compensating element of FIG. 7A.

FIG. 10A is a model cross-sectional view of a pair of optical dispersion compensating elements 900 in which the incident surfaces, which are one of the components of the composite type optical dispersion compensating element of the present invention, are arranged to face each other. FIG. 10B shows a pair of optical dispersion compensating elements 900 in which the incident surfaces constituting the composite type optical dispersion compensating element of the present invention are arranged facing each other, viewed from the direction of arrow 941 in FIG. 1OA. See diagram.

FIG. 11A is a diagram showing a corner cube.

FIG. 11B is a diagram for explaining a corner cube.

Fig. 12A is a diagram for explaining the method of compensating the second and third order chromatic dispersion. FIG. 4 is a diagram for explaining an inter-characteristic and a light intensity-one-hour characteristic.

FIG. 12B is a diagram for explaining a method of compensating for second and third order chromatic dispersion, and is a diagram for explaining a transmission path.

FIG. 12C is a diagram illustrating second-order and third-order chromatic dispersion, and is a diagram illustrating a transmission path.

FIG. 13 is a graph showing dispersion-wavelength characteristics of a conventional optical fiber. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Each drawing used for the description schematically shows dimensions, shapes, arrangement relations, and the like of each component so that the present invention can be understood. For convenience of description of the present invention, the magnification may be partially changed in the drawings, and the drawings used in the description of the present invention may not necessarily be similar to the actual products and descriptions in the embodiments and the like. Also, in each of the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted.

Fig. 1 is a diagram illustrating a method of compensating dispersion generated in communication using an optical fiber as a transmission line with an optical dispersion compensating element, and reference numeral 1101 denotes a signal remaining after compensating for secondary dispersion. The group velocity delay time-wavelength characteristic curve showing the third-order dispersion of light, 1102 is the group velocity delay time-wavelength characteristic curve of the dispersion compensator, and 1103 is the dispersion characteristic of the curve 111 the dispersion of the chromatic signal light, curve 1 1 0 2 compensated wavelength band after To償dispersion compensating device having a dispersion characteristic; in group velocity delay wave characteristic curve between I ~ e _2, vertical The axis is the group velocity delay time, and the horizontal axis is the wavelength.

FIGS. 2 to 4 show the respective optical dispersion compensating elements used in the present invention (in the present invention, the element itself capable of performing dispersion compensation and the element composed of them are widely referred to as an optical dispersion compensating element. Due to the above-mentioned necessity, for example, each element constituting the composite type optical dispersion compensating element of the present invention may be referred to as an optical dispersion compensating element. When it is not particularly necessary to distinguish the dispersion compensating element alone, the dispersion compensating element alone may be referred to as a light dispersion compensating element. When it is necessary to separately describe the compensating element alone, it may be referred to as an optical dispersion compensating element alone. As described above, when the optical dispersion compensating element is composed of a plurality of elements capable of performing dispersion compensation, when the element itself capable of performing dispersion compensation as a constituent element is to be described or defined, the following is required. Is also referred to as an element capable of performing dispersion compensation. When a part of a multilayer film formed on the same wafer or chip and capable of performing dispersion compensation is referred to, that part is also referred to as a part of an element capable of performing dispersion compensation. . FIG. 2 is a view for explaining an example of an element which can perform dispersion compensation, which constitutes FIG. 2. FIG. 2 is a cross-sectional view of a multilayer film described later, FIG. 3 is a perspective view of a multilayer film having a changed film thickness, and FIG. Is a group velocity delay time-wavelength characteristic curve of the multilayer film.

FIG. 2 is a diagram schematically illustrating a cross section of a multilayer film used as an example of a third-order optical dispersion compensating element used in the present invention. In FIG. 2, reference numeral 100 denotes a multilayer film as an example of a light-dispersing optical compensation element used in the present invention, 101 denotes an arrow indicating the direction of incident light, 102 denotes an arrow indicating the direction of emitted light, and 103 and 104 denote arrows. A reflective layer having a reflectivity of less than 100% (hereinafter also referred to as a reflective film or a light reflective layer), 105 is a reflective layer having a reflectivity of 98 to 100%, and 108 and 109 are a light transmissive layer (hereinafter simply referred to as a transmissive layer). Also, 1 1 1 and 1 1 2 are cavities. Reference numeral 107 denotes a substrate, for example, made of BK-7 glass (trade name of Dokku Shot Co., Ltd.).

The reflectances R (103), R (104), and R (1.05) of each of the reflective layers 103, 104, and 105 in FIG. 2 are in the relationship of R (103) ≤R (1 04) ≤R (105) . It is preferable in terms of mass production that the reflectance of each reflective layer is set to be different from each other at least between the reflective layers adjacent to each other with the light transmitting layer interposed therebetween. That is, the reflective layer is formed so that the reflectance of each reflective layer with respect to the center wavelength λ of the incident light gradually increases from the side where the incident light is incident toward the thickness direction of the multilayer film. It is particularly preferable that the reflectance of each reflective layer with respect to the light of the above wavelength is 60% R (103) ≤ 77%, 96% ≤ R (104) ≤ 99.8%, 98% ≤ R ( 105) and satisfying the magnitude relation of R (103), R (104), and R (105), the group as shown in FIG. 4 and FIG. A speed delay time-wavelength characteristic curve can be obtained. It is more preferable to set R (103) to R (104) to R (105), and it is more preferable to set R (105) closer to 100% or more preferably to 100%. The performance of the compensating element can be further improved. Then, in order to make it easier to manufacture the light dispersion compensation element used in the present invention, it is necessary to select the formation conditions of each reflection layer so that the intervals when considered as the optical path length between the adjacent reflection layers are different. Preferably, the design conditions for the reflectance of each reflective layer can be relaxed, and the combination of unit films whose film thickness is a quarter of the wavelength (that is, a film whose film thickness is an integral multiple of λ / 4) can be used. A multilayer film used for the tertiary light dispersion compensating element used in the present invention can be formed, and a highly reliable tertiary light dispersion compensating element having excellent mass productivity can be provided at low cost.

Although the thickness of the unit film of the multilayer film is described as being a quarter of the wavelength; L, as described above, this is within the range of an allowable error in film formation in mass production. / 4 means the current multilayer film forming technology, and generally means λ / 4 ± 1% in the present invention; L / 4 film thickness. The invention has a particularly great effect. However, even if films deviated from λ / 4 ± 1% to a direction having a slightly larger error coexist, a multilayer film capable of obtaining a group velocity delay time-wavelength characteristic curve described later as the entire multilayer film is the present invention. It can be said that it is a “multilayer film in which unit films each having a thickness of one quarter of the wavelength are stacked”. In particular, by setting the thickness of the unit film to え ± 0.5% (in this case, / is no error; meaning /), variation can be achieved without impairing mass productivity. A small and highly reliable multilayer film can be formed, and a light dispersion compensating element as described later with reference to FIGS. 5A to 5D and FIGS.

Further, in the present invention, it is described that the multilayer film is formed by stacking unit films each having a thickness of / 4, but this is achieved by forming one unit film and then forming the next unit film. The method described above can be repeated to form a multilayer film. However, the present invention is not limited to this. In general, a film having a thickness of an integral multiple of λ / 4 is often formed continuously. Of course, a multilayer film is also included in the multilayer film of the present invention.

In fact, some examples of the multilayer film of the present invention could be formed by using a film forming step of continuously forming the reflection layer and the transmission layer.

FIG. 3 is a front view of the multilayer film 100 in FIG. FIG. 4 is a diagram illustrating an example in which the thickness of the multilayer film 100 is changed.

In FIG. 3, reference numeral 200 denotes a multilayer film as an example of a light dispersion compensating element used in the present invention, 201 denotes a first reflective layer, 202 denotes a second reflective layer, 203 denotes a third reflective layer, and 205 denotes a substrate. , 206 is the first light transmitting layer, 207 is the second light transmitting layer, 211 is the first cavity, 212 is the second cavity, 220 is the light incident surface, 230 is the arrow indicating the direction of the incident light, 240 is an arrow indicating the direction of the emitted light, 250 is an arrow indicating the first thickness change direction, 260 is an arrow indicating the second thickness change direction, and 270 and 271 are directions for moving the incident position of the incident light. It is an arrow showing.

In FIG. 3, a third reflective layer 203, a second light transmitting layer 207, and a second reflective layer 202 are formed on a substrate 205 made of, for example, BK-7 glass (trade name of Schott, Germany). The first light transmitting layer 206 and the first reflecting layer 201 are sequentially formed.

As the thickness of the first light transmitting layer 206 changes in the direction indicated by the arrow 250 in FIG. 3 (the thickness gradually increases from right to left in the figure), and the thickness of the second light transmitting layer 207 changes. The multilayer film is formed so that the thickness changes in the direction indicated by arrow 260 (the thickness gradually increases from the front of the figure to the other side). The thicknesses of the first to third reflective layers are defined as first, second, and third when the resonance wavelength of the first and second cavities coincides with the center wavelength L of the incident light. The reflectance of each of the reflective layers of R (10 3), R (104) and R (105) is in accordance with the magnitude relation of R (103), that is, the reflectance of the reflective layers 201, 202, and 203 is R (20 1), R (202), R (203) are formed so as to satisfy R (20 1) ≤R (202) ≤R (203) .

FIG. 4 shows a case where incident light is incident from the direction of an arrow 230 in FIG. 3 on an incident surface 220 of a multilayer film (hereinafter, also simply referred to as a light dispersion compensation element) 200 as an example of the light dispersion compensation element of the present invention. When the emitted light is obtained in the direction of arrow 240 and the incident position of the incident light is moved in the direction of arrow 270 or 271 in FIG. 3 as described later, the change of the group velocity delay time-wavelength characteristic curve It is to explain.

Fig. 4 shows the group velocity delay time vs. wavelength characteristic curve when incident light with a center wavelength is incident on the incident positions 280 to 282 in Fig. 3, the vertical axis represents the group velocity delay time, and the horizontal axis represents the wavelength. It is.

The directions indicated by the arrows 250 and 260 of the reflective layers 201 to 203 and the light transmitting layers 206 and 207 in FIG. 3, that is, the incident surface that is substantially parallel to the incident surface By appropriately selecting the conditions for changing the film thickness inward, when the incident position of the incident light on the incident surface 220 is moved in the direction indicated by the arrow 270, the group velocity delay time-wavelength characteristic curve While maintaining the shape of in almost the same shape, the band center wavelength λ of the group velocity delay time-wavelength characteristic curve. (For example, the group velocity delay time of a substantially symmetrical shape in FIG. 4, the wavelength giving the extremum in the wavelength characteristic curve 2801) changes, and the position changes from the position in the direction indicated by the arrow 271. When the incident position is moved, the wavelength; With almost no change, the shape of the group velocity delay time-wavelength characteristic curve can be changed as shown by the curves 2811 and 2812 in FIG. Each curve in FIG. 4 is obtained when the thickness of each film is monotonically increased in the directions of arrows 250 and 260 in FIG.

The band center wavelengths at the curves 2801, 2811, and 2812 in FIG. 4; L 0 is set at an appropriate wavelength in the graph of FIG. 4 according to the purpose of dispersion compensation. Alternatively, it may be set to approximately the center value of the wavelength range of the curve shown in FIG. 4, or may be appropriately determined according to the purpose of dispersion compensation. Also, the wavelength of each characteristic point of the curve, such as the extreme wavelength between the curve 280 1 to 281 2, the curve 280 1 to 281 1, and the curve 281 1 to 281 2 It is a matter of course that the correspondence such as the shape of the curve and the shape of the curve should be checked beforehand, even if it is not described here.

In this way, for example, first, the center wavelength of the band corresponding to the center wavelength of the incident light to be dispersion-compensated. The position of the incident light is moved in the direction of arrow 270 in FIG. 3 so as to match, and the content of the guarantee to be dispersion-compensated, that is, the dispersion situation of the incident light, is adapted to the dispersion compensation. The shape of the group velocity delay time-wavelength characteristic curve to be used is selected, for example, from each curve in FIG. 4, and correspondingly, the incident position is indicated in the direction indicated by the arrow 271 in FIG. By selecting such points as indicated by 0 to 282, the dispersion compensation required for the signal light can be effectively performed. As is apparent from the shape of the group velocity delay time-wavelength characteristic curve in FIG. 4, third-order dispersion compensation is performed using the optical dispersion compensating element of the present invention, for example, using the curve 2801. The second-order minute dispersion compensation can be performed by using a portion of the curve 2811 or 2812 that is relatively close to a linear component.

As described above with reference to FIGS. 2 to 4, the “element capable of performing dispersion compensation, which is a part of the dispersion compensation element” used in the present invention, is referred to as the “element capable of performing dispersion compensation”. It is clear from the explanation of each curve in FIG. 4 that the third-order dispersion can be compensated for in a certain wavelength range by using “”.

However, the wavelength bandwidth of the dispersion compensation that can be compensated by the “element that can perform dispersion compensation” alone is around 1.5 nm for the signal light whose wavelength is around 1.55 μηι, and the group velocity delay time Is often around 3 ps (picoseconds), and if the wavelength bandwidth of dispersion compensation is widened to support multi-channel optical communication, the group velocity delay is large enough to achieve sufficient dispersion compensation. It is difficult to gain time, and further improvements are desirable for widespread use in real-world communications. Therefore, the present invention will be described in more detail with reference to FIGS. 5A to 5D, FIGS. 6A to 6D, and FIGS. 5A to 5D illustrate a method of improving the group velocity delay time-wavelength characteristic using a plurality of elements capable of performing dispersion compensation using a multilayer film as described with reference to FIGS. 2 to 4. Fig. 5A shows the group velocity delay time vs. wavelength characteristic with one element capable of performing dispersion compensation used in the present invention, and Fig. 5B shows the shape of the group velocity delay time vs. wavelength characteristic curve which is almost the same. The two elements that can perform dispersion compensation at different wavelengths (hereinafter also referred to as extreme values) giving the peak value (hereinafter also referred to as extreme values) of the group velocity delay time-wavelength characteristic curve are connected in series. The group velocity delay time vs. wavelength characteristic of the optical dispersion compensating element of the present invention is shown in FIG. 5C. Three elements that can perform dispersion compensation with different group extremal wavelengths having substantially the same group velocity delay time-wavelength characteristic curve are shown. Group velocity of the optical dispersion compensator of the present invention connected in series Figure 5D shows the optical dispersion compensation used in the optical dispersion compensation method of the present invention in which three elements capable of performing dispersion compensation differing in the shape of the group velocity delay time vs. wavelength characteristic curve and the extremal wavelength are connected in series. 5 is a graph showing a group velocity delay time-wavelength characteristic of an element, wherein the vertical axis represents the group velocity delay time and the horizontal axis represents the wavelength.

The basic principle of the optical dispersion compensation method of the present invention is to use, for example, an optical dispersion compensating element having the characteristics shown in FIGS. 5A to 5D, for example, by using FIGS. 7, 8, and 10. A composite type optical dispersion compensating element as described later is constructed, and the optical type Appropriate place in an optical transmission line, for example, in a signal light path such as connected to an optical fiber in series, or in an amplifier, receiver, wavelength demultiplexer, or various devices of a relay station installed in the transmission line And compensating the dispersion of the signal light by making the signal light incident on the light dispersion compensating element.

5A to 5D, reference numerals 301 to 309 denote the group velocity delay time-wavelength characteristic curves of one element capable of performing dispersion compensation used in the present invention, and 310 denotes the present invention. The group velocity delay time vs. wavelength characteristic curve when two devices that can perform dispersion compensation and have different extremal wavelengths with almost the same shape of the group velocity delay time vs. wavelength characteristic curve are connected in series Reference numeral 311 denotes a group velocity when three elements capable of performing dispersion compensation with substantially the same shape of the group velocity delay time-wavelength characteristic curve used in the present invention and having different extreme wavelengths are connected in series. Delay time Wavelength characteristic curve, 3 1 2 Group velocity delay time Group velocity delay time when three elements capable of performing dispersion compensation with different shapes and extreme wavelengths are connected in series It is a one-wavelength characteristic curve. In Fig. 5A, the symbol a is the wavelength band for dispersion compensation, and b is the extreme value of the group velocity delay time.

The extreme values of the bandwidth and the group velocity delay time of the wavelength bands to be compensated for the curves 302 to 307 and 309 are almost the same, and the curve 308 is more dispersion than the curves 307 and 309. This is a group velocity delay time-wavelength characteristic curve in which the bandwidth of the compensation target wavelength band is narrow and the extreme value of the group velocity delay time is large. The extreme wavelengths of the curves 301 to 309 are different from each other as shown in the drawing.

In FIG. 5B and FIG. 5C, the extremum of the group velocity delay time of the group velocity delay time vs. wavelength characteristic curve 310 is 1.6 times that of a single element capable of performing dispersion compensation, The wavelength band to be compensated is about 1.8 times, and the extremum of group velocity delay time vs. wavelength characteristic curve 3 1 1 is about 2.3 times that of a single group velocity delay time. The bandwidth is about 2.5 times that of a single element that can perform dispersion compensation.

In Fig. 5D, the extremum of the group velocity delay time in the curve of the group velocity delay time-wavelength characteristic 312 is about three times that of a single element that can perform dispersion compensation. The bandwidth is about 2.3 times that of a single device that can perform dispersion compensation.

It is possible to perform dispersion compensation using a multilayer film as described in FIGS. The extreme value of the group velocity delay time of the group velocity delay time-wavelength characteristic curve of the element and the wavelength band to be dispersion-compensated vary depending on the configuration conditions of each reflection layer and each light transmission layer of the multilayer film. As shown in the curve 3108 of the group velocity delay time vs. wavelength characteristic curve where the wavelength band for dispersion compensation is relatively wide but the extreme value of the group velocity delay time is not so large as shown by the curve 3107 in Fig. 5D. An element capable of performing dispersion compensation having various characteristics, such as a group velocity delay time-wavelength characteristic curve, in which the wavelength band for dispersion compensation is narrow but the extreme value of the group velocity delay time is large can be realized.

Examples of the multilayer film used for an element capable of performing such dispersion compensation include the multilayer films A to H described in the section of the above “Disclosure of the Invention”. When an element capable of performing dispersion compensation was created using these multilayer films A to H, the extreme value of the group velocity delay time was 3 ps for signal light with a wavelength of about 1.55 μm. (Picoseconds), it was possible to realize a group velocity delay time-wavelength characteristic curve with a dispersion compensation wavelength band of 1.3 to 2.0 nm.

Each of the multilayer films A to H has two light transmission layers (cavities, that is, resonators for incident light) sandwiched between reflection layers in the thickness direction of the film from the incident surface, that is, two layers. Although the present invention is a two-cavity multilayer film, the present invention is not limited to this, and it is possible to use a multilayer film having various configurations such as three-cavity and four-cavity. The multilayer film of the present invention is a multilayer film having two or more cavities, and can obtain a group velocity delay time-one wavelength characteristic completely different from a multilayer film having one cavity.

A plurality of devices capable of performing this dispersion compensation are connected in series, and a dispersion compensation wavelength band having a group velocity delay-one wavelength characteristic capable of compensating for dispersion due to optical fiber transmission is 15 nm. Can be realized. This optical dispersion compensating element is used as a third-order dispersion compensating element for a 30-channel communication system with a wavelength bandwidth of 0.5 nm and a channel wavelength of 0.5 nm near 1.55 μηι, equivalent to 1 OOG bps. When optical communication was performed for 60 km transmission, communication could be performed without any harm from third-order dispersion.

Elements that can be used in series to perform dispersion compensation, such as the group velocity delay time-wavelength characteristic curve in Fig. 4 and the combination of group velocity delay time-wavelength characteristic curves of different shapes in Fig. 5D Group delay time vs. wavelength characteristics By doing so, not only third-order dispersion but also second-order dispersion can be compensated. In the example of the light dispersion compensating element in which at least two elements capable of performing dispersion compensation according to the present invention are connected in series, for example, a light having a group velocity, a delay time, and a wavelength characteristic required to compensate for the third-order dispersion. In order to realize a dispersion compensating element, it is desirable to use at least one element capable of performing dispersion compensation having a group velocity delay time-wavelength characteristic curve having an extreme value in the wavelength region to be compensated for dispersion.

In order to more effectively perform dispersion compensation of a communication transmission line, it is desirable to improve the group velocity delay time-wavelength characteristic curve as an optical dispersion compensating element. As one method for this, there is a method having means for adjusting the group velocity delay time-wavelength characteristic of an element capable of performing dispersion compensation.

As a method, as described with reference to FIGS. 2 and 3, the thicknesses of the light-transmitting layer and the reflecting layer of the multilayer film are changed in the in-plane direction of the incident plane (that is, in the direction parallel to the incident plane of the element). By changing the relative incident position of the signal light in the device that can perform dispersion compensation, and changing the group velocity delay time-wavelength characteristic of the device that can perform dispersion compensation, Is raised. As a means for changing the incident position of the incident light, the light dispersion compensating element 200 or at least one of the incident positions of the incident light itself is moved with respect to the position of the incident light. It was realized. The light dispersion compensating element or the means for moving the incident light can be variously selected depending on the circumstances, such as the circumstances in which the light dispersion compensating element is used, the cost, and the characteristics. For example, due to the cost or the circumstances of the equipment, it is possible to use a method that is performed by manual means such as screws, and it is also possible to make adjustments for accurate adjustment or when manual adjustment is not possible. In order to achieve this, it is effective to use, for example, an electromagnetic step motor or continuous drive motor, and it is also effective to use a piezoelectric motor using PZT (lead zirconate titanate). It is a target. In addition, it is possible to easily and accurately select the incident position by using a prism-core collimator that can be combined with these methods, or by selecting the incident position by an optical means such as using an optical waveguide. be able to. Further, means for selecting an optical path in the composite type optical dispersion compensating element of the present invention is provided in engagement with the composite type optical dispersion compensating element, and optical path selection is performed by the same means as the above-mentioned incident position selecting means. By using it, the practical effect can be enhanced.

Also, by making at least one cavity of the multilayer film, for example, an air gap cavity to make the air gap variable, the group velocity delay time-wavelength characteristic can be changed.

Wherein each layer of the multilayer film of the element capable of performing dispersion compensation used for optical dispersion compensation device of the present invention, the thickness created by the wave of S I_〇 ₂ of ion-assisted deposition of 4 minutes film (hereinafter, Ion'ashisu a layer formed by preparative layer also referred to as) a thickness that is composed of a layer H formed in Ion'ashisu preparative layer of T i 0 ₂ of a quarter wavelength. A combination layer of the above-mentioned one SiO ₂ ion-assisted film (layer L) and one Ti ₂ ion-assisted film (layer H) is referred to as one set of LH layers. The term "set and stack" means "layer L, layer H, layer L 'layer H, layer L, layer H, layer L. layer H, layer H, layer H, layer H in order. It means that.

Similarly, the LL layer is referred to as a set of LL layers formed by laminating two layers L composed of a SiO ₂ ion-assist film having a quarter wavelength thickness. Therefore, for example, “three layers of LL are stacked” means “formed by stacking six layers L”.

As the composition of the film forming the layer H, although an example of a dielectric, the present invention is not limited thereto, other T i 0 ₂ as the same dielectric material as T i 0 ₂ a, T a ₂ 〇 _5, N b ₂ 〇 ₅ or the like can be used, further, in addition to the dielectric material, it is also possible to form a layer H with S i and G e. When the layer H is formed using Si or Ge, there is an advantage that the layer H can be formed thinner than the optical properties. Also, although an example of S i 0 ₂ As the composition of the layer L, but S i 0 ₂ has the advantage of forming a low cost yet reliable layer L, the present invention is not limited thereto If the layer L is formed of a material having a lower refractive index than the refractive index of the layer H, a light dispersion compensating element exhibiting the above effects of the present invention can be realized. Further, in the present embodiment, the layer L and the layer H constituting the multilayer film are formed by ion-assisted vapor deposition, but the present invention is not limited to this, and ordinary vapor deposition, sputtering, ion plating, and the like are performed. Even if a multilayer film formed by the above method is used, the present invention exhibits a great effect.

The light dispersion compensating element of the present invention can be used by appropriately holding a wafer-like element such as a multilayer film 200 as a light dispersion compensating element shown in FIG. In the thickness direction, that is, in the direction of thickness, that is, in the direction from the incident surface 220 to the substrate 205, for example, perpendicularly, the chip is cut into small pieces. The form has various possibilities, for example, it can be used as a compensating element. In any case, the main effects described in the present invention can be obtained.

FIG. 6 is a diagram for explaining a method of connecting a plurality of elements capable of performing dispersion compensation in series to realize a group velocity delay time-wavelength characteristic curve as in the example described in FIG. A shows an example in which two elements capable of performing the dispersion compensation are connected in series to form a light dispersion compensation element, and FIG. 6B shows three elements capable of performing the dispersion compensation connected in series. Figure 6C shows an example in which the optical dispersion compensating element is configured as shown in Fig. 6C. In the multilayer film, the thickness of which changes in the plane of incidence, two signal light incident positions are connected in series along the signal light path. FIG. 6D is a diagram showing an example in which the optical dispersion compensating element having the same configuration as that of FIG. 6A is mounted in one case. ,

6A to 6D, reference numerals 410, 420, 430, and 440 denote an optical dispersion compensating element configured by connecting a plurality of elements capable of performing dispersion compensation as described above in series, 411, 412, 421 to 421. 423, 431, 442, and 443 are elements capable of performing dispersion compensation, 416 is a multilayer film used for an element capable of performing dispersion compensation, 415, 415 1 to 4154, 426, 4261, and 4262 , 436, 436 1, 4362, 446, 4461, 4462 are optical fibers, 413, 413 1, 414, 4141, 424, 425, 434, 435, 444, 445 are arrows indicating the direction of signal light travel, 417 is a lens, 418 is a two-core collimator composed of the lens 41 7 and optical fibers 41 51 and 41 52, 441 is a case, and 43.1 is a multilayer film whose film thickness changes in the incident plane direction. It can be formed on a substrate to perform dispersion compensation. 432 and 433 are "element parts capable of performing dispersion compensation", respectively. Further, among the above optical fibers, reference numerals 415, 4152, 426, 436, and 446 are optical fibers as internal connection parts, and reference numerals 4151, 4153, 4154, 4261, 4262, 4361, 4362, 4461, and 4462 are An optical fiber as an external connection part.

In FIG. 6A, the signal light that has entered the element 41 1 capable of performing dispersion compensation from the optical fiber 41 53 in the direction of the arrow 413 is subjected to dispersion compensation to the element 411 capable of performing dispersion compensation. From the optical fiber 415, and is incident on an element 412 capable of performing dispersion compensation by being transmitted through an optical fiber 415. The optical fiber 41 54 is transmitted in the direction.

Reference numeral 4112 denotes a portion surrounded by a broken line 4111 of the element 411 capable of performing dispersion compensation, and is a diagram for explaining the internal structure thereof. The optical fibers 4151 and 4152 and the lens 4117 constitute a two-core collimator 418, and the signal light that has traveled along the optical fiber 4151 in the direction of the arrow 413 enters the multilayer film 416 through the lens 417.

The multilayer film 416 has, for example, a group velocity delay time-wavelength characteristic as shown in FIG. 5A, and the signal light incident on the multilayer film 416 through the optical fiber 4151 and the lens 417 is: The third-order dispersion compensation is performed, and the light exits from the multilayer film 416, passes through the lens 417 again, enters the optical fiber 4152, proceeds in the direction of arrow 4141, and enters the element 412 capable of performing dispersion compensation. . In this case, the optical fiber 4152 and the optical fiber 4.15 are substantially the same fiber, and the optical fiber 4151 and the optical fiber 4153 are also substantially the same. The signal light that has been further subjected to dispersion compensation by the element 41 2 capable of performing dispersion compensation emits from the element 412 capable of performing dispersion compensation, and the optical fiber 41 54 passes in the direction indicated by the arrow 414. proceed.

The optical dispersion compensating element 410 shown in FIG. 6A has the group velocity delay time-wavelength characteristic shown in FIG. 5B, and the signal light incident on the optical dispersion compensating element 410 is shown in FIG. Optical dispersion with dispersion compensation according to the group velocity delay time-wavelength characteristic curve as shown The light is emitted from the compensating element 410.

At this time, the signal light traveling along the optical fiber 4151 in the direction of the arrow 4131 is incident on the multilayer film 416 via, for example, a 2-core collimator 418 to be subjected to dispersion compensation. In the process of being reflected by the multilayer film 4 16, entering the optical fiber 4 152, and exiting in the direction of the arrow 4 141, the optical fiber 4 151 travels in the direction of the arrow 4 With respect to the incident light of the optical dispersion compensating element 4 10, the outgoing light of the optical dispersion compensating element 4 10 traveling in the direction of the arrow 4 1 4 1 through the optical fiber 4 15 2 is approximately smaller than the incident light. It receives coupling loss of 0.3 to 0.5 dB or more (also called coupling loss). This loss is extremely small compared to dispersion compensation using a conventional fiber grating.However, when dispersion compensation is required with less loss in a wide wavelength band of 15 nm and 30 nm. In this case, since the number of elements connected in series and capable of performing dispersion compensation described in FIG. 5 increases, this coupling loss is accumulated and becomes a large loss. For example, if 10 elements capable of performing dispersion compensation are connected in series by the above connection method, a power coupling loss of 3 to 30 dB is generated. This loss becomes a serious problem when constructing an optical dispersion compensator having a wide wavelength bandwidth of 15 nm or 30 nm.

An object of the present invention is to provide an optical dispersion compensation element and an optical dispersion compensation method capable of performing dispersion compensation with a small loss even in such a wide wavelength band. This will be described later with reference to FIG.

Before that, the dispersion compensation will be described in more detail in order to further understand the present invention. Similarly, in the optical dispersion compensating element 420 of FIG. 6B, the signal light incident on the optical dispersion compensating element 420 from the direction of the arrow 424 through the optical fiber 422 is firstly dispersed. The element which can perform compensation is input to the element 4 21 which can perform compensation, and is emitted after being subjected to dispersion compensation, and is sequentially transmitted to the element 4 22 to 4 23 which can perform dispersion compensation via the optical fiber 4 26. In the process of entering and exiting, for example, dispersion compensation is performed according to the group velocity delay time-wavelength characteristic curve as shown in FIG. In the direction indicated by the arrow 4 25.

Fig. 6C shows the part of the element 431 that can perform dispersion compensation formed on the same wafer instead of the elements 411 and 412 that can perform dispersion compensation in Fig. 6A. Figure 4 shows an example of an optical dispersion compensating element 430 in which `` 4 3 2 and 4 3 3 '' are connected in series along the path of signal light using an optical fiber 4 36. It is the same as described for A.

However, it is clear from the above description that the manner in which dispersion compensation is performed depends on the group velocity delay time-wavelength characteristic of an element capable of performing dispersion compensation. Fig. 6D shows an example in which the same dispersion compensating elements 4 4 2 and 4 4 3 as those in Fig. 6 A are incorporated in the same case 4 4 1 to provide a signal light communication path via an optical fiber 4 4 6. A light dispersion compensating element 440 is connected in series along the line, and although not shown, the element 443 capable of performing dispersion compensation is a multilayer film described with reference to FIG. It uses a multilayer film whose film thickness changes in the direction of the incident plane, and has means for adjusting the incident position. Although the incident position adjusting means is not shown, the incident position can be adjusted by using a control circuit provided in the case 441 and an incident position adjusting means driving circuit controlled by the control circuit. Has become. The signal light enters the optical dispersion compensating element 4440 via the optical fiber 4461, and exits from the optical dispersion compensating element 4440 via the optical fiber 4446.

In order to be able to broaden the wavelength band to be subjected to dispersion compensation in the dispersion compensation element and the dispersion compensation method using the same according to the present invention, for example, a multilayer film is used as described above. A plurality of elements capable of performing dispersion compensation can be connected in series in the optical path to form a dispersion compensation element having the purpose described with reference to FIGS. 5A to 5D. What is necessary is just to compensate dispersion using a dispersion compensation element.

As described with reference to FIGS. 6A to 6D, when a plurality of elements capable of performing the dispersion compensation of the present invention are connected by using a collimator, the number of the elements to be connected increases. For example, optical loss due to the connection becomes a major problem. Therefore, as a method for greatly reducing the optical loss due to this connection, the present inventors have proposed a dispersion compensation element using the connection method illustrated in FIGS. 7A, 7B and 8 in the present invention. I will propose.

7A and 7B are views for explaining the composite type optical dispersion compensating element of the present invention. FIG. 7A is a side view, and FIG. 7B is a view seen from above. The dotted line in Figure 7B is above it This is shown for convenience of explanation of a part that cannot be seen.

7A and 7B, reference numeral 701 denotes a composite type optical dispersion compensating element, and reference numerals 703 and 704 denote optical dispersion compensating elements used in the present invention constituting the composite type optical dispersion compensating element 701. As described below, examples of a plurality of devices, each of which can perform dispersion compensation used in the present invention, connected in series along the optical path of signal light, as described below. Plate, 7 11 and 7 2 1 are formed on the substrate and have a group velocity delay time-wavelength characteristic as described above with respect to incident light, 7 30 is a later-described film shown in FIG. 7 4 1 to 7 4 7, 7 5 0, 7 6 0 to 7 6 7 are the optical paths of the incident light, 7 8 1 and 7 8 2 are the optical fibers, 7 8 Reference numerals 3 and 784 denote lenses, and reference numerals 708 and 709 denote arrows indicating the direction in which the thickness of the light transmitting layer forming the multilayer film changes. d 1 and d 2 are the intervals at the illustrated positions of the optical dispersion compensating elements 703 and 704, respectively.

The composite type optical dispersion compensating element 701 is composed of optical dispersion compensating elements 703 and 704 provided to face each other as shown in the figure.

In FIG. 7A, the signal light transmitted through the optical fiber 781 passes through the lens 783, and from the optical path 741 to the light dispersion compensating element 703 constituting the light dispersion compensating element 701. The light is subjected to dispersion compensation at the incident point of the multilayer film 711 (an intersection point of the optical path 740 and the multilayer film 711) as an element capable of performing dispersion compensation by being incident, and is reflected. The light reaches the dispersion compensating element 704, is subjected to dispersion compensation at the incident point of the multilayer S 721 as an element capable of performing dispersion compensation, is reflected, and then passes through the optical path 743 to 747. Each of the multilayer films 711 and 721 as elements capable of performing dispersion compensation is alternately subjected to dispersion compensation at the point of incidence and reflected, and furthermore, the optical paths 750, 760 to 766 are formed. As a result, the light is reflected after being subjected to dispersion compensation at the incident point of the multilayer film 721 or 711, and is emitted from the composite optical dispersion compensation element 701 through the optical path 676. Te, incident from the lens 7 8 4 to the optical fiber 7 8 2, is transmitted through the optical fiber 7 8 2.

As can be seen from the above description, the optical dispersion compensating elements 703 and 704 can perform dispersion compensation at each signal light incident point (this incident point is both an incident point and a reflection point). It is a light dispersion compensating element in which elements are connected in series along the optical path of incident light, that is, signal light. As shown in FIG. 7A, the optical dispersion compensating elements 703 and 704 constituting the composite type optical dispersion compensating element 701 have an interval d1 on the upper side of the figure and an interval d2 on the lower side of the figure. And are arranged facing each other. In this case, the interval dl is formed to be narrower than the interval d2, and the light incident through the optical path 741 reaches the optical path 7550, the reflection direction is reversed, and the optical paths 7600 to 76.6 The light exits from the optical path 767 via In a preferred example, although not limited to this, the incident angle of the incident light is set to about 5 degrees with respect to the normal of the multilayer film 711, d1 is set to 1 O mm, and the beam of the incident light in the optical path 741 is set. By setting the diameter to about 1 mm, good output light can be obtained from the optical path 767.

In the optical dispersion compensating elements 703 and 704, the multilayer films 711 and 721 are formed on the substrates 710 and 702, respectively. The thickness of the film constituting the multilayer film changes from the bottom to the top of the figure in the direction of change different from that in FIG. 3, but changes in the same manner as described with reference to FIG. The thickness varies depending on the location).

As an example, the thickness of each of the light transmitting layers of the multilayer films 7 1 1 and 7 2 1 is formed so as to increase in the directions of arrows 708 and 709. Therefore, the content of the dispersion compensation that the incident light received at the respective positions of the optical dispersion compensating elements 703 and 704 described above with reference to FIG. 7A differs according to the description with reference to FIG. The shape and the extremum of the group velocity delay time-wavelength characteristic curve at each position are different from each other. The signal light that enters the composite type optical dispersion compensating element 70 1 from the optical path 7 41, undergoes dispersion compensation by the optical dispersion compensating elements 7 03 and 7 04, and exits from the optical path 7 67 is shown in FIG. For the same reason as described above using FIGS. 5A to D, the group velocity delay time-wavelength characteristic curve at each position of the optical dispersion compensating elements 703 and 704 is obtained as described later with reference to FIG. The dispersion compensation is performed according to the group velocity delay time-wavelength characteristic curve that is almost similar to the synthesized group velocity delay time-wavelength characteristic curve.

In this case, the signal light causes an optical loss when it enters or exits from the optical fiber and when it is reflected after being subjected to dispersion compensation in the optical dispersion compensating element. The former mainly causes a coupling loss (loss), and the latter a signal loss. Mainly causes reflection loss.

In general, the present inventors have found that the reflection loss is much smaller than the coupling loss and the properties thereof are different. That is, dispersion compensation The above-mentioned reflection loss at the point where the noise is applied occurs only in the vicinity of the wavelength that gives the extreme value of the group velocity delay time-wavelength characteristic curve at that position, and the peak value is approximately 0.1 ldB or less. At other wavelengths, it is almost negligible. The loss of the signal light from the time when the signal light enters the composite type optical dispersion compensating element 70 1 according to the present invention, undergoes the dispersion compensation as described above, and is emitted, depends on each of the incident points (reflection points). 6) The reflection loss is the same as that described above, and the element that can perform dispersion compensation as described in Figs. The coupling loss is greatly reduced compared to the coupling loss when connected in series along the optical path of light. '

FIG. 8 shows another example of the composite type optical dispersion compensating element of the present invention. In the figure, reference numeral 72 denotes a composite type optical dispersion compensating element of the present invention, 705 denotes a substrate, and 706 denotes a substrate. Reference numeral 707 denotes an optical dispersion compensating element formed on the substrate 705 and formed of a multilayer film having a group velocity delay time and one wavelength characteristic with respect to incident light as described above. Arrows indicating the direction of incidence of light, and 786 are arrows indicating the direction of emission of signal light. The substrate 705 is formed so that the lower part is gradually thicker than the upper part in the figure, and is formed so as to exhibit the same operation as that of the distances 41 and d2 described in FIG. 7A.

In the multilayer film constituting the optical dispersion compensating elements 706 and 707, the thickness of the film constituting the multilayer film changes as in the case of FIG. 7A (that is, the thickness of the multilayer film is It depends on the position in the inside).

In FIG. 8, the signal light incident on the composite type optical dispersion compensating element 72 from the arrow 785 travels through the substrate 7 05 for the same reason as in FIG. 0 6 or 7 0 7, undergoes dispersion compensation, is reflected by the multilayer film constituting the light dispersion compensating element 7 06 or 7 0 7, travels through the substrate 7 0 5, and has an arrow 7 8 6 Emit in the direction of.

The multilayer film and the multilayer films 711 and 721 constituting the optical dispersion compensating elements 706 and 707 are arranged in the same manner as described with reference to FIGS. It has the function of performing dispersion compensation corresponding to the speed delay time-wavelength characteristic.

The multilayer films 711 and 721 of FIG.7A are formed on the substrates 710 and 720, respectively, and have at least two reflective layers and at least one light transmitting layer. ing. The reflectance of the reflective layer constituting each multilayer film with respect to the central wavelength of the incident light is higher than that of the reflective layer existing on the incident surface of the incident light on the surface of each multilayer film or the reflective layer closest to the surface of each multilayer film. Each reflection layer is formed such that the next reflection layer provided with the light transmission layer between the reflection layer and the substrate has a higher reflectance. Each multilayer film has at least one reflective layer having a reflectance of 99.5% or more, and the reflective layer closest to the surface of the multilayer film or the reflective layer closest to the surface of the multilayer film. Each anti-It layer is formed such that the reflectivity of each reflective layer existing between the reflective layers with a reflectivity of 99.5% or more increases sequentially from the surface to the substrate. . This reflection layer is a single reflection layer with the reflection layers on both sides of the light transmission layer interposed therebetween, and the reflectance of each reflection layer is the unit of each layer H, layer L, etc. that constitute each reflection layer It does not refer to the reflectivity of the film, but to the reflectivity of the single reflective layer.

The number of reflective layers and light-transmitting layers in each multilayer film in Fig. 7A is, for example, in the case of a 2-cavity structure with three reflective layers and two light-transmitting layers, four reflective layers and three light-transmitting layers In the case of three cavities, there are many possible forms, such as four reflective layers and five light transmitting layers, and a multilayer film can be constructed according to the required dispersion compensation. Use it.

The light dispersion compensating elements 706 and 707 in FIG. 8 are also each composed of a multilayer film, have at least three reflective layers and at least two light transmission layers, and have a reflectivity of 99.5%. Having at least one reflective layer as described above is the same as in FIG. 7A, but the reflectance is sequentially from the reflective layer closest to the substrate to the first reflective layer with a reflectance of 99.5% or more. It is different from the case of Fig. 7A in that the configuration is larger.

Also, in FIG. 7, the distances d 1 and d 2 between the optical dispersion compensating elements 703 and 704 are taken as d 1 and d 2, and the difference between d 1 and d 2 is set to an appropriate value. As a result, the positions of the incident light and the reflected light that are incident on the optical dispersion compensating elements 703 and 704 disposed opposite to each other are arranged opposite to each other as shown in FIG. 7A. It can be on the same side of the optical dispersion compensating elements 703 and 704.

Then, by changing the difference between the distances d1 and d2, the positions of the incident light and the reflected light are shifted to different sides of the optical dispersion compensating elements 703 and 704 disposed opposite to each other. You can also. Further, by setting the distances d 1 and d 2 to dl = d 2, the positions of the incident light and the reflected light are opposite to the light dispersion compensating elements 70 3 and 70 4 which are arranged opposite to each other. You can also

FIG. 9 is a graph illustrating a group velocity delay time-wavelength characteristic curve of the composite type optical dispersion compensating element 701 of FIG. 7A. In FIG. 9, reference numeral 8001 denotes each group velocity at the incident position of each optical path of the optical dispersion compensating elements 703 and 704 constituting the composite optical dispersion compensation element 701.Delay time vs. wavelength characteristic This is a group of group velocity delay time-wavelength characteristic curves as a set of curves, and indicates the direction of the film thickness change of the multilayer films 7 1 1 and 7 2 1 as described by the arrows 7 08 and 7 09 in FIG. By inverting, it becomes a symmetrical curve group. Reference numeral 800 denotes a group velocity delay time-wavelength characteristic curve obtained by combining all the curves of the group velocity delay time-wavelength characteristic curve group 8001, that is, a composite optical dispersion compensating element 7 0 1 according to the present invention. 7 is a group velocity delay time-wavelength characteristic curve of FIG.

The characteristics of the composite type optical dispersion compensating element 701 in terms of the group velocity delay time vs. wavelength characteristic include an extremum larger than the individual curves of the group velocity delay time vs. wavelength characteristic curve group 801 and a wider bandwidth. In addition to the above, the loss of light intensity is significantly reduced as described above, as compared with the case where the optical fiber and the lens are used for coupling as shown in FIGS. .

The group velocity delay time-wavelength characteristic curve in FIG. 9 shows that the dispersion compensation wavelength bandwidth value and the group velocity delay time as a compensation amount can be considerably increased as compared with the conventional optical dispersion compensating element. Depending on the communication system, a wider bandwidth and a larger amount of compensation are required. A preferred embodiment of the composite light scattering / compensation element of the present invention that can satisfy such a requirement will be described below with reference to FIGS. 10A and 10B and 11A and 11B. FIGS. 10A and 10B are diagrams illustrating a particularly preferred embodiment of the composite type optical dispersion compensating element of the present invention. FIG. 10A is a diagram showing components of the composite type optical dispersion compensating element of the present invention. FIG. 10B is a model cross-sectional view of a pair of optical dispersion compensating elements 900 in which the incident surfaces are arranged so as to face each other, and FIG. 10B is an incident surface forming a composite type optical dispersion compensating element of the present invention. Fig. 11A shows a pair of optical dispersion compensating elements 900 arranged opposite to each other, as viewed from the direction of the arrow 941 of Fig. 1OA. Fig. 11A shows the reflectors 91 of Fig. 1OA and Fig. 10B. 1 is a diagram showing a corner cube as an example, and FIG. 11B is a diagram for explaining a corner cube. Figure 1 The dashed line at 0B shows the portion that is invisible because it is below the portion above it for convenience of explanation.

In FIGS. 10A and 10B and FIGS. 11A and 11B, reference numeral 900 denotes a pair of light beams having a pair of incident surfaces, which constitute a part of the composite type optical dispersion compensating element of the present invention, opposed to each other. Dispersion compensating elements, 901 and 902 are optical dispersion compensating elements alone, 91 1 to 913 are reflectors, 921 to 922 are optical fibers, 930 to 935, 9301 to 9303, 931 1 to 9313, 932:! ~ 9323, 933:! ~ 9333, 971 ~ 974 is the optical path of the signal light, 941 is the arrow, 950, 9500 is the corner cube, 951 ~ 953 is the corner cube 950 is the reflecting surface of the cube 960, the inner wall of the cube 960, 960 is the corner Cubes 951 1 to 95 16 and 961 to 963 for explaining cube 950 are a solid line and a broken line indicating the cutting position of cube 960.

As shown in FIG. 1 OA, the optical dispersion compensating elements 901 and 902 are arranged so that the signal light incident surfaces face each other, and the signal light emitted from the optical fiber 921 passes through the optical path 930 to be transmitted through the optical path 930. The light enters the incident surface of the dispersion compensating element 902, is subjected to dispersion compensation, is reflected (that is, exits from the light dispersion compensating element 902), and enters the light dispersion compensating element 901 through the optical path 931. Dispersion compensation. Similarly, the signal light that has been subjected to dispersion compensation by the optical dispersion compensating element 901 proceeds to an optical path 932, is again subjected to dispersion compensation by the optical dispersion compensating element 902, reflects, travels to an optical path 933, and again The dispersion compensating element 901 is subjected to dispersion compensation and reflected, and travels to an optical path 934.The dispersion compensation element is subjected to dispersion compensation, reflected and travels to an optical path 935 by the dispersion compensating element 902. The light exits from the pair of light dispersion compensating elements 900 and enters the reflector 911. Then, the signal light incident on the reflector 911 is reflected by the reflector 911 and is again directed to the optical dispersion compensating element 902 in a direction parallel to and opposite to the optical path 935, and from the optical path 935, for example, The light enters through an optical path slightly deviated in the depth direction of FIG. 1 OA, and is subjected to dispersion compensation a plurality of times by the optical dispersion compensating elements 902 and 901 in the same manner as described above.

In addition, when the traveling direction of the signal light described above is viewed from the direction indicated by the arrow 941, as shown in FIG. 10B, the signal light emitted from the optical fiber 921 travels along the optical path 9301, and the optical dispersion compensation is performed. Incident on the element unit 902, and the optical dispersion compensating element unit 9 At 0 2 and 9 0 1, the light travels along the optical path 932 while the dispersion compensation is performed a plurality of times alternately as described above, and the light exits from the optical dispersion compensating element 9 0 2 and travels along the optical path 9 3 0 3. The light is incident on the reflector 9 11.

The reflector 911 reflects the light incident from the optical path 9303 and emits the light to the optical path 931 1. The optical path 9303 and the optical path 931 1 are located at different positions of the light dispersion compensating elements 9 01 and 9 02 as shown in the figure, are parallel to each other, and are in opposite directions.

The signal light reflected by the reflector 911 in this way travels along the optical path 931 and is subjected to dispersion compensation multiple times alternately by the reproducing dispersion compensating elements 902 and 901 alone. While traveling, the light travels along the optical path 9 3 1 2, exits from the optical dispersion compensating element 9 0 2, and travels along the optical path 9 3 13, on the side opposite to the reflector 9 11 of the optical dispersion compensating element 9 0 0 The light is incident on the placed reflector 9 12.

The signal light reflected by the reflector 912 travels along the optical path 9321, and is subjected to multiple dispersion compensation by the optical dispersion compensating elements 902 and 901, so that the optical path 932 Then, the light is emitted from the light dispersion compensating element 902 alone, travels along the optical path 932, and enters the reflector 913.

The signal light reflected by the reflector 913 travels along an optical path 9331, and undergoes a plurality of dispersion compensations in the optical dispersion compensating elements 902 and 901, while the optical path 93332 Then, the light is emitted from the optical dispersion compensating element 902, travels along the optical path 9333, and enters the optical fiber 9222.

Either one of the light dispersion compensating elements 90 1 and 90 2 may be a mirror (reflection plate), and in this case, the light is incident on the light dispersion compensating element a plurality of times by the mirror. A plurality of dispersion compensations can be performed.

The optical path 931 13 and the optical path 9321, and the optical path 932 and the optical path 9331 are located at different positions, respectively, are parallel and the traveling directions of light are opposite.

Note that FIGS. 10A and 10B illustrate the case where the signal light enters and exits from the pair of optical dispersion compensating elements in which the incident surfaces are arranged to face each other, and is performed by the optical dispersion compensating element alone 102. The present invention is not limited to this, and the signal light may be input and output separately from the light dispersion compensating element alone, and the signal light may be changed by changing the way the incident light is incident. The incident light dispersion compensating element alone can be changed as appropriate. In this case, the reflectors 911 to 913 can be realized by, for example, arranging a pair of reflectors facing each other in a direction parallel to the arrow 941 in FIG. 10A. By making the pair of reflectors arranged to face each other in an integrated structure or integrally formed with each dispersion compensating element alone, the size of the light dispersion compensating element can be reduced, and the reliability can be improved. Therefore, it is possible to provide an optical dispersion compensating element which is easy to mount and low in mass production cost.

Also, in FIGS. 7A-B, 8 and 10A-B, a pair of light dispersion compensating elements having incident surfaces arranged opposite to each other has been described. One of the light dispersion compensating elements, for example, the light dispersion compensating elements 704 and 707 and the light dispersion compensating element alone 90 1 are each replaced with a reflector, and the reflecting surface of each reflector and the light dispersion compensating element 7 are replaced. 0 3 and 7 0 6 and the single element of the optical dispersion compensating element 9 0 2 are arranged so as to face each other, and a composite similar to the optical dispersion compensating elements 7 0 1, 7 0 2 and 9 0 0 Type light dispersion compensating element. Such a composite type optical dispersion compensating element is also the optical dispersion compensating element of the present invention, and a great effect can be obtained by properly using it according to the purpose of dispersion compensation.

As an example of the reflectors 911 to 913, a corner cube 9550 shown in FIG. 11A can be used as the reflector. The corner cube is composed of three mutually orthogonal reflecting surfaces 951, 952, and 953, and the cube 9660 shown in FIG. 11B is replaced by broken lines 961 to 96. It has a shape cut at the position indicated by 3. And the reflecting surfaces 951 to 953 are the same as the cube 960 and the symbol 951 :! This is the inside surface of the corner cupe (ie, the inside of the cube when it is a cube) cut at the positions indicated by ~ 9516.

The signal light incident on the corner cube 9550 from the optical path 971 is reflected by the reflective surface 951, passes through the optical path 972, enters the reflective surface 952, and is reflected by the reflective surface 952. The light is reflected and enters the reflection surface 953 through the optical path 973, is reflected by the reflection surface 9553, passes through the optical path 964, and exits from the corner cup 9550.

As an example of the miniaturization of the corner cube 950, the cube 960 can be cut at the positions indicated by broken lines 961 to 963 to form the corner cube 9500. Since the size of the reflecting surface is half that of the corner cube 950, Although there are restrictions on each optical path, it is basically the same as that of the corner cube 9550. As described above, the most significant feature of the present invention is that a composite type optical dispersion compensating element combining a plurality of optical dispersion compensating elements including at least a pair of optical dispersion compensating elements arranged with their incident surfaces facing each other. It is configured to perform dispersion compensation using the same, and the number of lenses and optical fibers for connection is reduced except for the input end and the output end of each of the optical dispersion compensating elements configured as described above. However, depending on the configuration, they are not required, and an optical dispersion compensating element with extremely small optical loss that can perform dispersion compensation even in a wide wavelength band can be provided at low cost. As described above, an example of a light dispersion compensating element in which one ffl ^ incident surface is arranged oppositely, or a compound type light dispersion compensating element in which the reflecting surface of a reflector and the incident surface of the light dispersion compensating element are arranged oppositely. The light dispersion compensating element according to the present invention has been described above, but the present invention is not limited to this, and the light dispersion compensating element is configured by combining a plurality of sets of light dispersion compensating elements whose incident surfaces are opposed to each other. The present invention includes, for example, a combination of a light dispersion compensating element whose surface is opposed to a light dispersion compensating element whose input surface is not opposed to the light dispersion compensating element.

According to the dispersion compensating element of the present invention and the dispersion compensating method of performing dispersion compensation using the dispersion compensating element having substantially the same configuration as that of the composite type compensating element, a wide wavelength such as 15 nm and 30 ηm can be obtained. It can be applied not only to bandwidths but also to communication systems that handle wavelength bands as narrow as 1 nm in optical communications, for example, and can also be applied to communication systems that handle wavelength bands of 3 nm or 5 to 10 nm. In any case, the extremely large effects as described above can be obtained.

By using such a composite optical dispersion compensator according to the present invention to compensate for dispersion in a communication system that transmits 60 km at a communication bit rate of 40 Gbps, extremely good dispersion compensation is achieved. And the loss due to the transmission of the signal light through the optical dispersion compensator is extremely low compared to the case where the optical dispersion compensator is performed only with a collimator consisting of a lens and an optical fiber. Met.

As described above, the composite type optical dispersion compensating element of the present invention and the optical dispersion compensating method using the element have been described centering on the optical dispersion compensating element used in the present invention. The characteristic to be achieved is that at least one pair of the plurality of light dispersion compensating elements used in the present invention is arranged with the incident surfaces facing each other, and the pair of light dispersion compensating elements arranged opposite to each other. The signal light is incident on one side, is reflected by performing dispersion compensation, is incident on the other optical dispersion compensating element, is reflected by performing dispersion compensation there, and is incident again on the one optical dispersion compensating element to thereby perform dispersion compensation. Is performed a plurality of times between the pair of optical dispersion compensating elements, and a loss generated between the time when the signal light is incident on the pair of optical dispersion compensating elements and the time when the signal light is emitted is reflected. Without the coupling loss described above, only the reflection loss that is overwhelmingly smaller than the coupling loss, making it possible to perform second- and third-order low-loss dispersion compensation over a wide wavelength band. It is in the place. One of the notable features of the optical dispersion compensation method of the present invention is that a composite type optical dispersion compensation element in which the reflecting surface of the reflector and the incident surface of the optical dispersion compensation element are arranged to face each other. It can be used in the same manner as a composite type optical dispersion compensating element in which the incident surfaces of the pair of optical dispersion compensating elements are arranged to face each other.

Further, the optical dispersion compensating element of the present invention is appropriately configured to have a wide wavelength band, for example, 1260 to: 1360 nm, 1360 to 1460 nm, 1460 to 1 530 nm, 1

Group velocity delay with at least one extreme in any one of the following wavelengths: 530 to 155 nm, 156 to 165 nm, 166 to 165 nm It is also possible to configure the dispersion compensating element to have a time-wavelength characteristic curve so that optimal compensation can be performed in accordance with the communication situation.

It is also possible to configure the dispersion compensating element so as to have a group velocity delay time-wavelength characteristic curve having an extreme value at a plurality of wavelengths in a wavelength range of 60 to 170 nm. The present invention makes use of such a large degree of freedom to make it possible to perform secondary and tertiary dispersion compensation required in actual communication, and makes use of many of the conventional optical communication systems. It enables high speed and long distance communication. Industrial availability

As described above, the present invention has been described in detail.According to the present invention, by preparing various group velocity delay time-wavelength characteristic curves described with reference to FIGS. In addition to this, good dispersion compensation for multiple channels can be performed. The dispersion compensation by the optical dispersion compensating element of the present invention has a particularly great effect in the third-order dispersion compensation, and also has a large group velocity delay time. By appropriate adjustment of the wavelength characteristics, secondary dispersion compensation can be performed.

INDUSTRIAL APPLICABILITY The present invention is indispensable for the practical use of high-speed and long-distance optical communication such as transmitting 100,000 km at 40 Gbps, has a wide range of use, and develops the optical communication field. It greatly contributes to.

The optical dispersion compensating element using the special multilayer film according to the present invention is small in size, suitable for mass production, and can be provided at a low price, which greatly contributes to the development of optical communication.

By using the optical dispersion compensation device of the present invention, in that it allows to take advantage of many existing optical communication systems, social and economic effects is of great _c

Claims

The scope of the claims

1. A composite type optical dispersion compensating element combining an optical dispersion compensating element capable of compensating dispersion as chromatic dispersion by using an optical fiber for communication using a communication transmission line, wherein the composite type optical dispersion In the compensating element, at least a part of the light dispersion compensating elements constituting the compensating element faces at least a part of a light incident surface on the at least some light dispersion compensating elements, and A composite type optical dispersion characterized in that an incident surface of an optical dispersion compensating element different from the optical dispersion compensating element or a reflecting surface of a reflector which is also referred to as a reflector A below is arranged. Compensating element.

2. The composite type optical dispersion compensating element according to claim 1, wherein at least a part of the optical type dispersion compensating element constituting the composite type optical dispersion compensating element uses a multilayer film capable of compensating dispersion. A composite light dispersion compensating element characterized by being a light dispersion compensating element having a so-called multilayer film element.

3. The composite light dispersion compensating element according to claim 1, wherein the light dispersion compensating element is opposed to at least a part of the light incident surface constituting the composite light dispersion compensating element. The light dispersion compensating element on which the incident surface of another light dispersion compensating element or the reflecting surface of the reflector A is disposed has a so-called multilayer element which is an element using a multilayer film capable of compensating for dispersion. A composite light dispersion compensating element characterized by being a light dispersion compensating element.

4. The composite light dispersion compensation element according to claim 1, wherein the light dispersion compensation element faces at least a part of the light incident surface of the composite light dispersion compensation element. The incident surface of another light dispersion compensating element or the light incident surface of the light dispersion compensating element in which the reflecting surface of the reflector A is disposed and the light dispersion surface of the another light dispersion compensating element disposed opposite thereto. Either one or both of the incident surface and the reflecting surface of the reflector A are flat, and the composite type optical dispersion compensating element is characterized in that:

5. The composite light dispersion compensating element according to claim 1, wherein the light dispersion compensating element faces at least a part of the light incident surface constituting the composite light dispersion compensating element. The incident surface of another light dispersion compensating element or the light incident surface of the light dispersion compensating element in which the reflecting surface of the reflector A is disposed and the light dispersion surface of the another light dispersion compensating element disposed opposite thereto. A composite light dispersion compensating element, wherein one or both of the incident surface and the reflecting surface of the reflector A is a curved surface.

6. The composite type optical dispersion compensating element according to claim 2, wherein the multilayer element constituting the optical dispersion compensating element comprises at least three reflective layers and at least two light transmitting layers. Wherein the one light transmission layer is formed so as to be sandwiched between two reflection layers of the reflection layer, and the multilayer film has a wavelength of incident light, When the wavelength is λ, the reflective layer has at least one reflective layer having a reflectance of 99.5% or more with respect to a central wavelength referred to as a central wavelength λ, and extends from the incident surface in the thickness direction of the multilayer film. The reflectivity of each of the reflective layers arranged up to the position of the reflective layer where the reflectivity which appears first as 99.5% or more increases gradually as it proceeds in the thickness direction of the multilayer film from the incident surface side A composite type optical dispersion compensating element characterized in that:

7. The composite type optical dispersion compensating element according to claim 1, wherein at least a part of a light incident surface of the optical dispersion compensating element is opposed to another optical dispersion compensating element. The reflector A, which is hereinafter referred to as a reflector B, is opposed to or near at least a part of the light dispersion compensating element in which the entrance surface of the element or the reflection surface of the reflector is arranged. A composite light dispersion compensating element, characterized in that a reflector or a reflecting portion different from the above is provided.

8. The composite type optical dispersion compensating element according to claim 7, wherein the reflector B is formed from one of a pair of optical dispersion compensating elements whose incident surfaces are opposed to each other or is incident thereon. A light dispersion compensating element in which the reflection surface of the reflector A is disposed opposite to the surface, and a light referred to as light A output from one of the reflectors A, and a light dispersion. A composite light dispersion compensating element, which is arranged so as to be able to enter the compensating element or the reflector A.

9. The composite type dispersion compensating element according to claim 8, wherein the light A is incident as light referred to as reflected light B by the reflector B, but the light A is emitted. A composite light dispersion compensating element characterized by being an element or a reflector A.

10. The composite type optical dispersion compensating element according to claim 9, wherein an emission position of the light A and an incident position of the light B in the optical dispersion compensation element are different from each other. Light dispersion compensating element.

11. The composite light dispersion compensation element according to claim 9, wherein the light A and the light B are parallel and travel in opposite directions.

12. The composite light dispersion compensation element according to claim 7, wherein the reflector B has at least three reflecting surfaces.

13. The composite light dispersion compensating element according to claim 12, wherein at least one reflecting surface of the reflector B is movable.

14. The composite type optical dispersion compensating element according to claim 10, wherein the means for driving the movable reflecting surface of the reflector B is a manual means or an electric means. Type light dispersion compensation element.

15. The composite type optical dispersion compensating element according to claim 14, wherein the reflector B is also referred to as a single optical dispersion compensating element of a pair of optical dispersion compensating elements arranged so that the incident surfaces face each other. Light emitted from any one of the light dispersion compensating elements, or light emitted from the reflection surface of the reflector A disposed opposite to the light dispersion compensation element So that at least one pair of the light dispersion compensating elements or the light dispersion compensating elements disposed so as to face each other and the end of the reflector A on the same side of the reflector A so as to reflect the light. Or a pair of reflector portions are provided on at least one of a pair of light dispersion compensating elements whose incident surfaces are opposed to each other, or a light dispersion compensating element and a reflector which are opposed to each other. A composite light dispersion compensating element, which is provided integrally with at least one of A.

16. The composite light dispersion compensation element according to claim 12, wherein the reflector B is a corner cube.

17. The composite type optical dispersion compensating element according to claim 9, wherein the light B is one of a pair of optical dispersion compensating elements arranged such that the light-entering surfaces face each other, or the light B is directed to the opposite side. The direction in which the light A enters one of the disposed light dispersion compensating element and the reflector A and travels later is parallel to the traveling direction in which the light A travels in the light dispersion compensating element before the light A exits. And a composite type optical dispersion compensating element characterized by being in the opposite direction.

18. The composite type optical dispersion compensating element according to claim 7, wherein the light is disposed at an end of a pair of optical dispersion compensating elements having the incident surfaces opposed to each other, or at the end of the pair of optical dispersion compensating elements. A composite light dispersion compensating element comprising a dispersion compensating element and a reflector B provided at a plurality of locations at the end of the reflector A.

19. The composite type optical dispersion compensating element according to claim 18, wherein the incident surface of each of the individual optical dispersion compensating elements of the pair of optical dispersion compensating elements disposed opposite to each other is provided. The traveling direction of the signal light that is incident on the incident surface of the optical dispersion compensating element disposed to face the reflector A and travels while undergoing dispersion compensation is changed from one side of the incident surface to the other side. A composite type optical dispersion compensating element characterized in that, in a moved position, the directions are sequentially and alternately opposite.

20. The composite type optical dispersion compensator according to claim 3, wherein the incident surfaces are opposed to each other. A composite light dispersion compensating element characterized in that each light dispersion compensating element of one light dispersion compensating element arranged in this manner is constituted by a multilayer film element formed on a different substrate.

21. The composite type optical dispersion compensating element according to claim 3, wherein at least one pair of the optical dispersion compensating elements of the at least one pair of the optical dispersion compensating elements, the incident surfaces of which are opposed to each other, emit incident light. A composite light dispersion compensating element, wherein an incident surface is formed on the mutually opposing surfaces of the same substrate capable of transmitting light so that an incident surface is on the substrate side.

22. The composite type optical dispersion compensating element according to claim 20, wherein at least three layers from the substrate side of a multilayer film constituting at least one of the optical dispersion compensating element and each of the individual optical dispersion compensating elements. A composite light dispersion compensating element, wherein the reflectance of the reflective layer of the layer increases from the reflective layer closer to the substrate to the reflective layer farther from the substrate.

23. The composite type optical dispersion compensating element according to claim 1, wherein at least one pair of the optical dispersion compensating elements in which at least one pair of the incident surfaces are arranged to face each other, or the optical dispersion compensating element is incident. The incident position and the emission position of the signal light of the optical dispersion compensating element in which the surface and the reflecting surface of the reflector A are arranged to face each other are the same as those of the pair of optical dispersion compensating elements in which the incident surface is arranged to face. Alternatively, a composite type optical dispersion compensating element, which is located on different sides of the optical dispersion compensating element arranged to face the reflector A.

24. The composite type optical dispersion compensating element according to claim 1, wherein at least one set of the pair of optical dispersion compensating elements in which the incident surfaces are opposed to each other or the optical dispersion compensating element is incident. The incident position and the emission position of the signal light of the optical dispersion compensating element in which the surface and the reflecting surface of the reflector A are arranged to face each other are the same as those of the pair of optical dispersion compensating elements in which the incident surface is arranged to face. Alternatively, a composite light dispersion compensating element is provided on the same side of the light dispersion compensating element that is arranged to face the reflector A.

25. The composite type optical dispersion compensator according to claim 2, wherein at least one of the multilayer devices has at least five types of laminated films having different optical properties, that is, such as light reflectance and film thickness. A multilayer film having at least five laminated films having different optical properties, wherein the multilayer film has at least three types of reflective layers including at least two types of reflective layers having different light reflectances from each other; It has at least two light transmission layers in addition to the three types of reflection layers, wherein each one of the three types of reflection layers and each one of the two light transmission layers are alternately arranged, The multilayer film includes, in order from one side in the thickness direction of the film, a first layer that is a first reflective layer, a second layer that is a first light transmitting layer, a third layer that is a second reflective layer, It is composed of a fourth layer, which is a second light transmission layer, and a fifth layer, which is a third reflection layer. Let L be the central wavelength of the incident light, and L be the optical path length in the first to fifth layers, that is, the optical path length for the light of the central wavelength of the incident light. The film thickness is approximately an integer multiple of 1/4 ± 1%, and the multilayer film has a film thickness of approximately 1/4 times L and a refractive index of ± 1%. Is about 1/4 times ± 1% of L and has a low refractive index, and is composed of multiple sets of layers combining the upper layer, Layer L. ,

The multilayer film A is a layer in which the five-layer laminated film, that is, the first to fifth layers are combined one by one in the order of layer H and layer L in order from one side in the thickness direction of the multilayer film. The first layer composed of three sets of HL layers, the second layer composed of 10 sets of HH layers that are a combination of layers H and H, and one layer L composed of layers H and H The third layer is formed by laminating 7 sets of HL layers, the fourth layer is formed by laminating 38 sets of HH layers, 1 layer L and 13 sets of HL layers And a multi-layered film formed by the fifth layer composed of

Instead of the second layer, which is formed by laminating 10 sets of HH layers of the multilayer film A, the second layer is a multilayer film having the same direction as that of the multilayer film A. In order from one side in the thickness direction, 3 sets of HH layers, 3 sets of LL layers, which is a layer combining layers L and L, 3 sets of HH layers, 2 sets of LL layers, and 2 sets of HH layers One set of layers is a multilayer film formed by stacking layers in this order, and a multilayer film C is formed by stacking 38 sets of HH layers of the multilayer film A or B. In place of the fourth layer, the fourth layer has three sets of HH layers and three sets of LL layers in order from one side in the thickness direction of the film in the same direction as that of the multilayer film A, 3 sets of HH layers, 3 sets of LL layers, 3 sets of HH layers, 3 sets of LL layers, 3 sets of HH layers, 3 sets of LL layers, 3 sets of HH layers, 3 sets of LL layers, 3 sets of HH layers, 3 sets of LL layers, 3 sets of HH layers, 3 sets of LL layers, 2 sets of HH layers are stacked in this order It is a multilayer film composed of a multilayer film,

The multilayer film D is a layer in which the five-layered film, that is, the first to fifth layers are combined one by one in the order of layer L and layer H in order from one side in the thickness direction of the multilayer film. The first layer composed of 5 sets of LH layers, the second layer composed of 7 sets of LL layers, 1 layer H and 7 sets of LH layers The third layer is composed of: the fourth layer composed of 57 sets of LL layers, the fifth layer composed of one layer H and 13 sets of LH layers The multilayer film E is defined as: a multilayer film E, wherein the five-layer laminated film, that is, the first to fifth layers, are arranged such that two layers of HL are sequentially arranged from one side in the thickness direction of the multilayer film. The first layer is formed by stacking sets, the second layer is formed by stacking 14 sets of HH layers, and the second layer is formed by stacking 1 set of layer L and 6 sets of HL layers. 3 layers, HH layer 24 sections A fourth layer composed of a plurality of layers, and a multilayer film composed of a fifth layer composed of a single layer L and a fifth layer composed of a set of 13 HL layers,

Instead of the fourth layer formed by laminating 24 sets of the HH layers of the multilayer film E or F, the fourth layer is a film in the same direction as the multilayer film E. 3 sets of HH layers, 3 sets of LL layers, 3 sets of HH layers, 3 sets of LL layers, 3 sets of HH layers, 3 sets of LL layers in order from one side in the thickness direction of Set Layer, 3 sets of HH layers, 3 sets of LL layers, 2 sets of HH layers, 1 set of LL layers, and 1 set of HH layers. Is a multilayer film,

The multilayer film H is formed by laminating the five layers, that is, the first to fifth layers in order from one side in the thickness direction of the multilayer film, and laminating four sets of LH layers. The first layer, the second layer composed of 9 sets of LL layers, the third layer composed of 1 layer H and the 6 sets of LH layers, and the 3rd layer composed of 6 layers of LH layers When a multilayer film composed of a fourth layer composed of set laminations, a fifth layer composed of one layer H, and a fifth layer composed of 13 sets of LH layers,

A composite type optical dispersion compensation element, wherein at least one of the multilayer elements has at least one of the multilayer films A to H.

26. The composite type optical dispersion compensating element according to claim 2, wherein the thickness of at least one laminated film constituting the multilayered film of at least one of the optical dispersion compensating elements is a light incident surface of the multilayered film. A composite light dispersion compensating element characterized in that it changes in an in-plane direction in a cross section parallel to the plane, that is, in an in-plane direction, that is, the film thickness varies depending on the position in the laminated film.

27. The composite type optical dispersion compensating element according to claim 26, wherein each of the optical type dispersion compensating elements of the composite type optical dispersion compensating element, wherein at least one pair of the incident surfaces is arranged to face each other. A composite light dispersion compensation element, characterized in that at least one light transmission layer of a single light dispersion compensation element has a different thickness in different directions.

28. The composite type optical dispersion compensating element according to claim 27, wherein each optical dispersion compensating element of at least a pair of the opposing optical dispersion compensating elements constituting the composite type optical dispersion compensating element. A composite type optical dispersion compensating element characterized in that the thickness of at least one light transmitting layer of the multilayer film of the element alone changes in opposite directions.

29. The composite type optical dispersion compensating element according to claim 26, wherein the adjusting means adjusts the film thickness of at least one of the multilayer films by engaging with the optical dispersion compensating element, or And a means for changing a light incident position on an incident surface of the multilayer film.

30. The composite type optical dispersion compensating element according to claim 2, wherein at least one of the multilayer element elements is an optical dispersion compensating element capable of mainly capturing third-order dispersion. Type light dispersion compensation element.

3. The composite type optical dispersion compensating element according to claim 2, wherein at least one of the optical dispersion compensating elements is an optical dispersion compensating element capable of compensating secondary dispersion. Light dispersion compensation element.

32. The composite type optical dispersion compensating element according to claim 1, wherein at least a pair of the opposingly arranged lights out of the optical type dispersion compensating elements constituting the composite type optical dispersion compensating element. The incident surface of one of the dispersion compensating elements and the incident surface of the other one of the dispersion compensating elements, or the incident surface of the light dispersion compensating element disposed opposite to the incident surface of the reflector A. A reflection surface between the incident surface of one of the opposing light dispersion compensating elements and the incident surface of the other light dispersion compensating element, or an opposing light dispersion compensating element. It is arranged between the incident surface of the compensating element and the reflecting surface of the reflector A such that the light incident on the optical dispersion compensating element can be incident and reflected a plurality of times. A composite type optical dispersion compensating element, characterized in that:

33. The composite light dispersion compensation element according to claim 32, wherein at least a part of the light dispersion compensation element constituting the composite light dispersion compensation element can compensate for dispersion. A composite light dispersion compensating element characterized by being a light dispersion compensating element having a so-called multilayer film element, which is an element using a multilayer film.

34. The composite type optical dispersion compensation element according to claim 32, wherein the composite type light is An incident surface of a light dispersion compensating element different from the light dispersion compensating element or a reflecting surface of the reflector A is disposed so as to face at least a part of the light incident surface constituting the dispersion compensating element. A composite light dispersion compensating element, wherein the light dispersion compensating element is a light dispersion compensating element having a so-called multilayer film element which is a device using a multilayer film capable of compensating for dispersion.

35. The composite light dispersion compensation element according to claim 32, wherein the light dispersion compensation element faces at least a part of an incident surface of the light constituting the composite light dispersion compensation element. The light incident surface of another light dispersion compensating element or the light incident surface of the light dispersion compensating element in which the reflection surface of the reflector A is disposed, and the another light dispersion disposed opposite thereto. A composite light dispersion compensating element, wherein one or both of the incident surface of the compensating element and the reflecting surface of the reflector A are flat.

36. The composite light dispersion compensating element according to claim 32, wherein the light dispersion compensating element opposes at least a part of the light incident surface constituting the composite light dispersion compensating element. The light incident surface of another light dispersion compensating element or the light incident surface of the light dispersion compensating element in which the reflecting surface of the reflector A is disposed and the another light dispersion compensating member A composite type optical dispersion compensating element, wherein one or both of the incident surface of the element and the reflecting surface of the reflector A are curved.

37. The composite type optical dispersion compensating element according to claim 33, wherein the multilayer film element constituting the optical dispersion compensating element has at least two light-reflecting layers, which are also referred to as reflective layers, and at least two layers. A multi-layer film having a light-transmitting layer, wherein each of the one light-transmitting layers is formed so as to be sandwiched between two reflective layers of the reflective layer; The reflective layer has at least one reflective layer having a reflectivity of 99.5% or more with respect to a central wavelength referred to as a central wavelength when the wavelength is λ. The reflectivity of each of the reflective layers arranged up to the position of the reflective layer in which the reflectivity which appears first as proceeding in the thickness direction of the film is 99.5% or more increases from the incident surface side in the thickness direction of the multilayer film. The characteristic feature is that the size of the Combined light dispersion compensating element.

38. The composite type optical dispersion compensating element according to claim 32, wherein at least a part of a light incident surface of the optical dispersion compensating element is opposed to, and light different from, the optical dispersion compensating element. At least at a portion facing or near at least a part of the light dispersion compensating element in which the incident surface of the dispersion compensating element or the reflecting surface of the reflector A is arranged, the reflector B is referred to as A composite light dispersion compensation element characterized in that a reflector or a reflection part different from the reflector A is provided.

39. The composite type optical dispersion compensating element according to claim 38, wherein the reflector B is formed of any one of a pair of optical dispersion compensating elements whose incident surfaces are opposed to each other. A light dispersion compensating element in which a reflection surface of the reflector A is arranged opposite to an incident surface; and a light dispersion compensation device that reflects light referred to as light A output from any one of the reflectors A. The compound type optical dispersion compensating element is arranged so that it can be incident on the reflector A.

40. The composite type optical dispersion compensating element according to claim 39, wherein the light A is incident as light referred to as reflected light B by the reflector B, but the light A is emitted. A composite light dispersion compensating element, which is a dispersion compensating element or a reflector A. .

41. The composite type optical dispersion compensating element according to claim 40, wherein an emission position of the light A and an incident position of the light B in the optical dispersion compensation element are different from each other. Light dispersion compensating element.

42. The composite light dispersion compensation element according to claim 40, wherein the light A and the light B are parallel and travel in opposite directions.

43. The composite type optical dispersion compensation element according to claim 38, wherein the reflector B is A composite type optical dispersion compensator having at least three reflecting surfaces.

44. The composite light dispersion compensation element according to claim 43, wherein at least one reflection surface of the reflector B is movable.

45. The composite type optical dispersion compensating element according to claim 41, wherein the means for driving the movable reflecting surface of the reflector B is a manual means or an electric means. Type light dispersion compensation element.

46. The composite light dispersion compensation element according to claim 45, wherein the reflector B is also referred to as a single light dispersion compensation element of a pair of light dispersion compensation elements arranged so that the incident surfaces face each other. Out of any one of the light dispersion compensating elements, or the outgoing light from any one of the light dispersion compensating elements and the reflecting surface of the reflector A disposed opposite to the light dispersing element. As described above, a pair of optical dispersion compensating elements whose incident surfaces are opposed to each other, or at least a pair of forces provided at the same end of the reflector A with the optical dispersion compensating elements arranged opposite to each other. Or, a pair of reflector portions are provided on at least one of the pair of light dispersion compensating elements in which the incident surfaces are arranged opposite to each other, or on at least one of the light dispersion compensating element and the reflector A arranged in opposition to each other. Being provided integrally A composite type optical dispersion compensating element characterized by the following.

47. The composite light dispersion compensation element according to claim 43, wherein the reflector B is a corner cup.

48. The composite type optical dispersion compensating element according to claim 40, wherein the light B is any one of a pair of optical dispersion compensating elements arranged such that the incident surfaces face each other, or the optical B is arranged facing the light dispersion compensating element. The direction in which the light A enters one of the light dispersion compensating element and the reflector A and travels later is parallel to the traveling direction in which the light A travels in the light dispersion compensating element before the light A exits. And a composite type optical dispersion compensating element characterized by being in the opposite direction.

49. The composite type optical dispersion compensating element according to claim 38, wherein the light-entering surfaces are disposed at the ends of a pair of optical dispersion compensating elements disposed facing each other, or disposed opposite to each other. A composite light dispersion compensating element comprising a light dispersion compensating element and reflectors B provided at a plurality of locations at the end of the reflector A.

50. The composite type optical dispersion compensating element according to claim 49, wherein the incident surface of each of the pair of optical dispersion compensating elements arranged opposite to each other has an incident surface of each optical dispersion compensating element alone. The traveling direction of the signal light that is incident on the incident surface of the optical dispersion compensating element disposed to face the reflector A and travels while undergoing dispersion compensation is changed from one side of the incident surface to the other side. A composite type optical dispersion compensating element characterized in that, in a moved position, the directions are sequentially and alternately opposite.

51. The composite type optical dispersion compensating element according to claim 34, wherein each of the individual optical dispersion compensating elements of the pair of optical dispersion compensating elements arranged with the incident surface facing each other is provided on different substrates. A composite light dispersion compensating element comprising a multilayer element formed.

52. The composite type optical dispersion compensating element according to claim 34, wherein at least one pair of the optical dispersion compensating elements of the at least one pair of the optical dispersion compensating elements, the incident surfaces of which are arranged to face each other, the incident light. A composite light dispersion compensating element, characterized in that an incident surface is formed on the mutually facing surfaces of the same substrate capable of transmitting light, so that an incident surface is on the substrate side.

53. The composite type optical dispersion compensating element according to claim 51, wherein at least 3 from the substrate side of a multilayer film constituting at least one of the optical dispersion compensating element and each of the individual optical dispersion compensation elements. A composite light dispersion compensating element, wherein the reflectance of the reflective layer of the layer increases from the reflective layer closer to the substrate to the reflective layer farther from the substrate.

54. The composite type optical dispersion compensating element according to claim 32, wherein at least one pair of the incident surfaces is arranged so as to face each other, or a pair of the optical dispersion compensating elements are incident. The incident position and the emission position of the signal light of the optical dispersion compensating element in which the surface and the reflecting surface of the reflector A are arranged to face each other, A composite light dispersion compensating element, which is located on different sides of a light dispersion compensating element disposed opposite to the reflector A.

55. The composite type optical dispersion compensating element according to claim 32, wherein at least one pair of the incident surfaces is disposed so as to face each other, or the optical dispersion compensating element is incident. The incident position and the emission position of the signal light of the optical dispersion compensating element in which the surface and the reflecting surface of the reflector A are arranged to face each other, A composite light dispersion compensating element which is on the same side as the light dispersion compensating element disposed opposite to the reflector A.

56. The composite type optical dispersion compensating element according to claim 33, wherein at least one of the multilayer film elements has at least five kinds of laminated films having different optical properties, that is, light reflectance and film thickness. And the like, and the multilayer film has at least three types of reflective layers including at least two types of reflective layers having different light reflectances from each other. And at least two light transmission layers in addition to the three types of reflection layers, wherein one layer of each of the three types of reflection layers and one layer of each of the two light transmission layers are alternately arranged. The multilayer film includes, in order from one side in the thickness direction of the film, a first layer serving as a first reflective layer, a second layer serving as a first light transmitting layer, and a third layer serving as a second reflective layer. Layer, a fourth layer as a second light transmitting layer, and a fifth layer as a third radiating layer. In the first to fifth layers, the central wavelength of the incident light is L; and the optical path length, that is, the central wavelength of the incident light; The film thickness of each layer is approximately an integer multiple of L / 4 ± 1%, and the multilayer film has a film thickness of approximately 1/4 times I and 1% soil. It is composed of a combination of the layer H, which is the layer with the higher refractive index, and the layer L, which is the layer whose thickness is 1/4 times ± 1% and the refractive index is low, and the layer with the higher refractive index is about 1%. Yes, The multilayer film A is a layer in which the five-layer laminated film, that is, the first to fifth layers are combined one by one in the order of layer H and layer L in order from one side in the thickness direction of the multilayer film. The first layer composed of three sets of HL layers, the second layer composed of 10 sets of HH layers that are a combination of layers H and H, and one layer L composed of layers H and H The third layer is formed by laminating 7 sets of HL layers, the fourth layer is formed by laminating 38 sets of HH layers, 1 layer L and 13 sets of HL layers And a multi-layered film formed by the fifth layer composed of

The multilayer film D is a layer in which the five-layered film, that is, the first to fifth layers are combined one by one in the order of layer L and layer H in order from one side in the thickness direction of the multilayer film. The first layer composed of 5 sets of LH layers, the second layer composed of 7 sets of LL layers, 1 layer H and 7 sets of LH layers The third layer is composed of 5 layers of LL layers, the fourth layer is composed of 57 layers, and the fifth layer is composed of 1 layer of H and 13 sets of LH layers. Each of the multi-layer films is formed, and the multi-layer film E is composed of two sets of HL layers, in which the five-layer laminated film, that is, the first to fifth layers, are sequentially arranged from one side in the thickness direction of the multi-layer film. 1st layer composed of laminated layers, 14 sets of HH layers 2nd layer composed of laminated layers, 1 layer L and 6 sets of HL layers The third layer is constructed by laminating layers, the fourth layer is constructed by laminating 24 sets of HH layers, the layer is constructed by laminating one layer L and 13 sets of HL layers It is a multi-layered film formed on the fifth layer,

Instead of the fourth layer, which is formed by stacking 24 sets of the HH layers of the multilayer film E or F, the fourth layer has a multilayer film G in the same direction as that of the multilayer film E. In order from one side in the thickness direction, 3 sets of HH layers, 3 sets of LL layers, 3 sets of HH layers, 3 sets of LL layers, 3 sets of HH layers, 3 sets of LL layers Layer, 3 sets of HH layers, 3 sets of LL layers, 2 sets of HH layers, 1 set of LL layers, and 1 set of HH layers. Is a multilayer film,

A composite optical dispersion compensating element, wherein at least one of the multilayer elements has at least one of the multilayer films A to H.

5 7. The composite type optical dispersion compensating element according to claim 33, wherein at least one of the multilayer films of the optical dispersion compensating element has a film thickness of at least one of the multilayer films. Is changed in the in-plane direction in the cross section parallel to the incident surface, that is, in the in-plane direction, that is, the film thickness is different depending on the position in the laminated film. A composite type dispersion compensating element.

58. The composite light dispersion compensating element according to claim 57, wherein each of the light dispersion compensating elements in which at least a pair of the incident surfaces constituting the composite light dispersion compensating element are arranged to face each other. A composite light dispersion compensation element, characterized in that at least one light transmission layer of the multilayer film of the light dispersion compensation element alone has a different thickness in different directions.

59. The composite type optical dispersion compensating element according to claim 58, wherein each of the optical type dispersion compensating elements constituting the composite type optical dispersion compensating element has at least a pair of the optical dispersion compensating elements disposed opposite to each other. A composite type optical dispersion compensating element characterized in that the thickness of at least one light transmitting layer of the multilayer film of the element alone changes in opposite directions.

60. The composite type optical dispersion compensating element according to claim 57, wherein the adjusting means is configured to engage with the optical dispersion compensating element and adjust a film thickness of at least one of the multilayer films. Alternatively, there is provided means for changing a light incident position on an incident surface of the multilayer film, wherein the composite light dispersion compensating element is provided.

31. The composite type optical dispersion compensating element according to claim 33, wherein at least one of the multilayer film elements is an optical dispersion compensating element capable of mainly compensating third-order dispersion. Light dispersion compensating element.

62. The composite type optical dispersion compensating element according to claim 33, wherein at least one of the optical dispersion compensating elements is an optical dispersion compensating element capable of compensating secondary dispersion. Light dispersion compensating element.

6 3. An optical dispersion compensation method for compensating for dispersion as chromatic dispersion in communication using an optical fiber as a communication transmission line. Incident surface of optical dispersion compensating element different from dispersion compensating element, or Is a reflection surface of a reflector also referred to as a reflector A below, and the incident surfaces of both of the light dispersion compensating elements disposed opposite to each other, or the light dispersion disposed opposite to each other. The incident surface of the compensating element and the reflecting surface of the reflector A are arranged so that an optical path of incident light can be formed therebetween. Light configured so that incident light that has entered between an incident surface and the reflective surface can be incident and reflected on the incident surface of the optical dispersion compensation element a plurality of times while traveling along the optical path. An optical dispersion compensation method comprising: forming a composite optical dispersion compensation element including at least one set of dispersion compensation elements; and dispersing the incident light by propagating the incident light through the optical path.

64. The optical dispersion compensating method according to claim 63, wherein at least one pair of the optical dispersion compensating elements or a pair of the optical dispersion compensating elements and the reflector A are at least partially or in the vicinity. A light dispersion compensation method characterized by arranging a reflector or a reflector, also referred to as a reflector B below, to perform dispersion compensation of incident light.

65. The light dispersion compensation method according to claim 64, wherein the reflector B is output from a pair of light dispersion compensating elements or the light dispersion compensating element and the reflector A arranged opposite to each other. A method for compensating for dispersion of incident light, comprising arranging light, also referred to as light A hereinafter, so that the light can be reflected and made incident on the light dispersion compensating element, thereby performing dispersion compensation of the incident light.

66. The optical dispersion compensation method according to claim 65, wherein the light A is a light reflected by the reflector B, which is also referred to as a light B hereinafter, and the light A is a light dispersion compensation element from which the light A is emitted. An optical dispersion compensation method, comprising: disposing the optical dispersion compensating element and a reflector so as to be incident again to perform dispersion compensation of incident light.

67. The optical dispersion compensation method according to claim 66, wherein the emission position of the light A and the incident position of the light B in the optical dispersion compensation element are different positions. Optical dispersion compensation method.

68. The optical dispersion compensation method according to claim 66, wherein the light A and the light B are parallel and traveling in opposite directions.

69. The optical dispersion compensation method according to claim 65, wherein said reflector B has at least three reflecting surfaces.

70. The optical dispersion compensation method according to claim 69, wherein said reflector B is a corner cup.

71. The light dispersion compensation method according to claim 63, wherein at least one of the light dispersion compensation elements is a multilayer film element having a multilayer film capable of performing dispersion compensation. Optical dispersion compensation method.

72. The optical dispersion compensation method according to claim 71, wherein the film thickness of at least one laminated film constituting at least one of the multilayer films is in a cross section parallel to a light incident surface of the multilayer film. An optical dispersion compensation method characterized by being changed in the in-plane direction, that is, in the in-plane direction.

73. The optical dispersion compensation method according to claim 71, wherein at least one of the multi-layer film-forming elements is connected in series at a plurality or at a plurality of locations. 365 nm, 1360-1460 nm, 1460-1530 nm, 1530-1565 nm, 1565-1625 nm, 1 It is characterized by having a group velocity delay time-wavelength characteristic curve having at least one extreme value in at least one wavelength range of the wavelength range of 625 to 1675 nm. Optical dispersion compensation method.

74. The optical dispersion compensating method according to claim 63, wherein the signal light is separated in the optical path. An optical dispersion compensation method characterized in that a plurality of ways of connecting elements capable of performing dispersion compensation can be selected.

75. The optical dispersion compensation method according to claim 1, wherein the dispersion compensation of the signal light is a dispersion compensation capable of performing at least tertiary dispersion compensation.