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WO2001057567A1 - Dispositif a structures periodiques multiples de constante dielectrique, et procedes de conception et de production associes - Google Patents

Dispositif a structures periodiques multiples de constante dielectrique, et procedes de conception et de production associes Download PDF

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Publication number
WO2001057567A1
WO2001057567A1 PCT/JP2001/000781 JP0100781W WO0157567A1 WO 2001057567 A1 WO2001057567 A1 WO 2001057567A1 JP 0100781 W JP0100781 W JP 0100781W WO 0157567 A1 WO0157567 A1 WO 0157567A1
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Prior art keywords
periodic structure
period
wavelength
dielectric constant
lambda
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PCT/JP2001/000781
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English (en)
Japanese (ja)
Inventor
Ryoko Shimada
Takao Koda
Akira Ikushima
Takumi Fujiwara
Kazuo Imamura
Takeshi Genji
Original Assignee
Toyota School Foundation
Mitsubishi Cable Industries, Ltd.
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Application filed by Toyota School Foundation, Mitsubishi Cable Industries, Ltd. filed Critical Toyota School Foundation
Publication of WO2001057567A1 publication Critical patent/WO2001057567A1/fr

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02057—Optical fibres with cladding with or without a coating comprising gratings
    • G02B6/02076—Refractive index modulation gratings, e.g. Bragg gratings
    • G02B6/0208—Refractive index modulation gratings, e.g. Bragg gratings characterised by their structure, wavelength response
    • G02B6/02085—Refractive index modulation gratings, e.g. Bragg gratings characterised by their structure, wavelength response characterised by the grating profile, e.g. chirped, apodised, tilted, helical

Definitions

  • the present invention relates to a device having a periodic structure with a dielectric constant such as a photonic crystal, and a design method and a manufacturing method thereof. In particular, it relates to an element that selectively reflects a plurality of electromagnetic waves having different wavelength bands.
  • an optical fiber grating that can be considered as a one-dimensional photonic crystal mainly has a single periodic structure or a periodically changing periodic structure (ie, a chopped periodic structure) and propagates in the fundamental mode. It is used as a filter that selectively reflects light of a single wavelength (referred to as "short-period optical fiber grating"). However, even if a single periodic structure is used, if the period is long (100 ⁇ m order), coupling occurs between light propagating in different modes.
  • Optical fiber gratings (sometimes called “long-period optical fiber gratings”) are used as filters that transmit light of multiple wavelengths.
  • optical fiber grating has only been realized having a single periodic structure in both the short period and the long period. Therefore, A multi-reflection band optical fiber grating that reflects light of a plurality of different wavelengths and is applicable to a wavelength multiplexing transmission system that has become increasingly important in recent years has not been obtained.
  • the optical fiber grating As described using the optical fiber grating as an example, there are a limited number of elements that use a periodic structure with a refractive index (or dielectric constant, where the refractive index is the square root of the dielectric constant), and select multiple electromagnetic waves with different wavelength bands from each other. It has not yet been possible to obtain a device that reflects light.
  • Japanese Patent Application Laid-Open No. H10-2933222 discloses an optical fiber grating formed by superposing a plurality of gratings.
  • the technology disclosed in this publication merely produces optical fiber gratings having loss peaks corresponding to the respective gratings.
  • the two gratings are superimposed. Because the effect of the modulation of the periodic structure due to this is not taken into account at all, the spectral characteristics of the grating (such as the wavelength dependence of transmittance and reflectance) cannot be accurately controlled.
  • the pitch of the superimposed gratings is in the range of 0.53-0.58 zm, and this technique can be applied only to periodic structures having periods close to each other. Disclosure of the invention
  • the present invention has been made in view of the above problems, and a main object of the present invention is to provide a dielectric constant multi-period structure capable of realizing an element that selectively reflects a plurality of electromagnetic waves having different wavelength bands from each other.
  • An object of the present invention is to provide an element, a method of designing the element, and a method of manufacturing the element.
  • the dielectric constant multi-periodic structure element of the present invention includes a first periodic structure in which a dielectric constant changes in a first direction at a first period ⁇ i; a first periodic structure superimposed on the first periodic structure; longer second period lambda 2 in dielectric constant and a second periodic structure varies along the first direction, at least one of the first periodic structure and the second periodic structure, Chiyapu been periodic structure And an electromagnetic wave of a first wavelength i corresponding to the first periodic structure; and a short wavelength side of the first wavelength input i as a result of the first periodic structure being modulated by the second periodic structure. It has a configuration for selectively reflecting electromagnetic waves of the second wavelength band 2 and the third wavelength band 3 which are two side bands generated on the long wavelength side.
  • the first periodic structure Since at least one of the structure and the second periodic structure is chirped, not only the position (wavelength) of the selectively reflected electromagnetic wave but also the width of each reflection peak can be controlled. In particular, only the width of the side band can be controlled by making the second periodic structure a capped periodic structure.
  • the number of side bands generated by the double periodic structure including the first periodic structure and the second periodic structure superimposed on the first periodic structure is not limited to two (one pair), but four (two pairs). These sidebands can be generated. Further, three or more periodic structures may be superimposed along the first direction. In the case where a plurality of periodic structures are superimposed on the first periodic structure, a cyclic structure having a period and a single periodic structure may be combined.
  • first direction along a second direction different from, and a third periodic structure having a dielectric constant changing in the third period lambda 3, superimposed on the third periodic structure, longer fourth than the third period lambda 3 period lambda 4 in it may be configured that the dielectric constant is further having a fourth periodic structure which varies along the second direction.
  • the third period lambda 3 and the fourth period lambda 4 can be set to anything it the first period and second period lambda 2 independent.
  • An optical fiber element having a core and a cladding, wherein the first periodic structure and the second periodic structure are formed in the core, and the first direction is a core propagation direction or a core of the optical fiber element.
  • the second period lambda 2 may be a direction perpendicular arrangement to the propagation direction is preferably greater 5 times or more than the first period lambda i.
  • the dielectric constant may be continuously changed along the first direction. Continuously changing means that the envelope of the peak (or bottom) of the permittivity changes continuously (for example, according to a sine function), and is distinguished from discontinuous changes that follow a step function.
  • Another dielectric constant multi-periodic structure element includes: a first periodic structure in which a dielectric constant changes in a first period At along a first direction; and a first periodic structure superimposed on the first periodic structure. and a second circumferential periodic structure which varies along the dielectric constant first direction at a longer second period lambda 2, the electromagnetic wave of the first Hachoe i corresponding to the first periodic structure, said first Electromagnetic waves of the second wavelength 3 and the second wavelength 3 , which are two side bands generated on the short wavelength side and the long wavelength side of the first wavelength person i as a result of the periodic structure being modulated by the second periodic structure. And selectively reflected in a second direction different from the first direction.
  • the third period lambda 3 and the fourth period lambda 4 can be set to anything it the first period Hache and second periodic lambda 2 independent. According to this configuration, a two-dimensional or three-dimensional optical demultiplexer capable of extracting or confining light of different wavelengths in a plurality of different directions is obtained.
  • the second period lambda 2 is preferably also larger by 5 times than the first period. Further, the fourth period lambda 4, it is not preferable the third period lambda 3 5 times or more greater.
  • the dielectric constant may be continuously changed along the first direction. Further, in the fourth periodic structure, a configuration may be adopted in which the dielectric constant changes continuously along the second direction.
  • a chirped periodic structure can be used.
  • the method for manufacturing a refractive index multi-periodic structure element includes: a first periodic structure in which a refractive index changes in a first period along a first direction; and a first periodic structure superimposed on the first periodic structure. and a second periodic structure in which the refractive index varies along the first direction with a long second period lambda 2, at least one of the first periodic structure and the second periodic structure was in a periodic structure that is Ji Jaap An electromagnetic wave of a first wavelength corresponding to the first periodic structure; and a short wavelength side and a long wavelength side of the first wavelength as a result of the modulation of the first periodic structure by the second periodic structure.
  • An optical fiber having a core and a cladding surrounding the core is provided. Irradiating the optical fiber with the writing light, a first periodic structure in which a refractive index changes in a first period, and a second period that is superimposed on the first period and is longer than the first period ⁇ i. and a second periodic structure in which the refractive index in the period lambda 2 is changed along the first direction comprises the step of forming the core.
  • the formation of the first periodic structure and the formation of the second periodic structure may be performed in separate steps (separate manufacturing method) or may be performed in the same step (simultaneous manufacturing method).
  • this The manufacturing method can be applied to the manufacture of a refractive index multi-periodic structure element in which three or more refractive index periodic structures are superimposed in the same direction.
  • the second period lambda 2 is preferably also larger by 5 times than the first period.
  • the method for designing a dielectric constant multi-periodic structure element according to the present invention includes: a first periodic structure in which a dielectric constant changes in a first period along a first direction; and a first periodic structure superimposed on the first periodic structure; in period a t longer than the second period lambda 2 and a second periodic structure having a dielectric constant varies along the first direction, and the electromagnetic wave of the first wavelength person i corresponding to the first periodic structure, prior to As a result of the first periodic structure being modulated by the second periodic structure, the second wavelength band 2 and the third wavelength band 3, which are two side bands generated on the short wavelength side and the long wavelength side of the first wavelength i.
  • Structural Determining a first period, and extending the second wavelength 2 and the third wavelength ⁇ longer than the first period and superimposed on the first period structure, and modulating the first period structure.
  • the laminated structure of the virtual dielectric layer may be formed by actually laminating a dielectric film, or by irradiating a film exhibiting a photoinduced refractive index change with writing light.
  • FIG. 1 is a diagram showing a model of a one-dimensional dielectric constant double periodic structure.
  • FIG. 2 is a diagram showing a band structure (calculation) of the dielectric constant double periodic structure shown in FIG.
  • FIG. 4 (a) is a graph showing the spectral transmittance characteristics of a conventional single-period optical fiber grating
  • Fig. 4 (b) shows its energy band diagram
  • Fig. 4 (c) shows a short-period structure and a long-period structure
  • FIG. 4D is a graph showing a spectral transmittance characteristic of the optical fiber bag grating according to the present invention having a dielectric constant multi-periodic structure modulated by
  • FIG. 4D is an energy band diagram thereof.
  • 6 (a), 6 (b) and 6 (c) are schematic diagrams for explaining the method of manufacturing the optical fiber grating of the present embodiment according to the present invention.
  • FIGS. 7 (a), (b) and (c) are schematic views showing the refractive index distribution (periodic structure) in each step of the method for manufacturing the optical fiber grating of the present embodiment shown in FIG. It is.
  • FIG. 8 is a diagram showing a spectral reflection spectrum of the optical fiber grating according to the first embodiment of the present invention.
  • FIG. 9 is a diagram showing a spectral reflection spectrum of the optical fiber grating according to the second embodiment of the present invention.
  • a first dielectric layer having a thickness a having a first dielectric constant e a and a second dielectric layer having a thickness b having a second dielectric constant e b ( ⁇ e a ) are alternately formed.
  • the magnitude of the dielectric constant of the first dielectric layer having a laminated structure of one cycle a + b is modulated by the periodic function of the following equation (1).
  • a a (x) ⁇ ( ⁇ 0 + 1) / 2 ⁇ + ⁇ ( ⁇ 0-1 ) / 2 ⁇ -f (p, x)
  • ⁇ & (i) ⁇ ( ⁇ 0 + 1) / 2 ⁇ + ⁇ ( ⁇ 0-1 ) / 2 ⁇ cos (2 ⁇ ⁇ )
  • p A l / A 2 ) be called the modulation parameter overnight.
  • X in FIG. 1 corresponds to i ⁇ a.
  • the energy spectrum of the dielectric multilayer film having the above-described dielectric constant double periodic structure is calculated using, for example, a transfer matrix method, similarly to the energy spectrum of the superlattice semiconductor.
  • the modulation spectrum the energy spectrum (transmission spectrum) calculated by changing the value of ⁇ in various ways.
  • a band structure as shown in FIG. 2 is obtained.
  • the vertical axis in Fig. 2 is the normalized photon energy (ka), and the horizontal axis is the normalized wave number vector (k vector: k vector along the stacking direction (X) of the multilayer film). Torr).
  • This band structure has the following parameters: a, b, ⁇ . And p. 3 paras overnight a, b and e. Determines the degree of localization of electromagnetic energy in the second dielectric layer.
  • the region indicated by the vertical solid line in FIG. 3 corresponds to the transmission band, and the blank region between the solid lines corresponds to the region where the transmittance is zero (photonic band 'gap').
  • the discontinuous black points in FIG. 3 are steep peaks in the transmission spectrum.
  • the above-mentioned document discloses that, by introducing a double periodicity into a dielectric multilayer film as a one-dimensional photonic crystal, the energy in which a photonic band gap does not originally exist in a single periodic structure Photonic with the desired width in the area- Bands-Theoretical indication of the possibility of a gap.
  • the inventor of the present application attempted to apply the present invention to an optical fiber grating in order to demonstrate the possibility theoretically shown above, and reached the present invention.
  • Fig. 4 (a) is a graph showing the spectral transmittance characteristics of a conventional single-period optical fiber grating, and Fig. 4 (b) is its energy band diagram.
  • FIG. 4 (c) shows an optical signal according to the present invention having a dielectric constant multiple period structure obtained by modulating a short period structure (also referred to as a first period structure or a basic period structure) with a long period structure (second period structure).
  • Fig. 4 (d) is a graph showing the spectral transmittance characteristics of the fiber grating, and Fig. 4 (d) is its energy band diagram. Each shows the calculation results. This calculation can be performed using a numerical calculation program using the transfer matrix method.
  • the transfer matrix method is a method of calculating the state of a light wave emitted through a substance from the state of a light wave incident from a certain direction using a determinant. Using the optical constants (dielectric constant and extinction coefficient), the light input / output characteristics are calculated.
  • the relationship between the period and the reflection wavelength is obtained based on the well-known Bragg diffraction condition.
  • the optical fiber grating of the present embodiment shown in FIGS. 5B to 5E light in a plurality of wavelength bands is selectively reflected.
  • This optical fiber grating of the present embodiment as described above, the first periodic structure of the first period, the second periodic structure having a longer second period lambda 2 than the first period are superimposed in, first wavelength region corresponding to the first cycle (light of human J (about 1.
  • the second periodic structure having the second period ⁇ 2 longer than the first period that is, modulating the first periodic structure with the second periodic structure
  • the wavelength at which the side band appears can be adjusted by changing the modulation parameter.
  • the number of sidebands generated by modulation is not limited to two (one pair), and higher-order sidebands are also generated, as shown in Figs. 5 (d) and (e).
  • a single optical fiber grating can selectively reflect a plurality of lights in mutually different wavelength bands.
  • Such an optical fiber rating can be suitably used as a wavelength selection element in wavelength division multiplex communication.
  • the wavelength range used for optical multiplexing communication is expanding year by year, and the wavelength range of light to be selectively reflected by optical fiber rating is widened and selected.
  • the modulation parameters Isseki p of the multi-periodic structure smaller than 1/5 .
  • optical fiber grating that can selectively reflect light of many wavelengths at a narrow wavelength interval over a wide wavelength range.
  • Such optical fiber grating can be suitably used for narrow band wavelength multiplex communication.
  • the first periodic structure (short-period structure) is modulated by the second periodic structure (long-period structure).
  • the third periodic structure is, of course, superimposed (triple periodic structure). You may. At this time, the period of the third periodic structure may be a short period or a long period. Of course, another periodic structure may be superimposed (a quadruple or more periodic structure).
  • the multiplexing of the periodic structure may be performed in the same direction, or may be performed in two or more different directions.
  • first periodic structure and the second periodic structure of the grating have been described as having the same pitch, but it is needless to say that one or both of them may be chirped.
  • a chirped grating is one in which the bit changes continuously, and the width (wavelength width) of the reflection peak expands depending on the degree of the chirp.
  • first periodic structure (short-period structure) Chiya makes one flop, shown in FIG. 5, the first wavelength EI second Hachoe second and third Hachoe; to control the width of the third peak Can be.
  • the width of the peak is wider than in the case where no chirp occurs.
  • second Hachoe second and third Hachoe 3 beaks position and peak width is a sideband generated by modulation Can be controlled.
  • the pitch of each periodic structure and the degree of the cap may be appropriately determined.
  • the direction in which light is reflected can be selectively adjusted by setting the direction of each periodic structure.
  • the dielectric constant multi-periodic structure element of the following embodiment is an optical fiber grating, and since the electromagnetic wave selectively reflected is light, it is intuitive to understand. Therefore, "refractive index" is used instead of "dielectric constant”.
  • an optical fiber grating is manufactured using light-induced refractive index change.
  • FIG. 6 a method for manufacturing the optical fiber grating of the present embodiment will be described.
  • the optical fiber grating of the present embodiment is manufactured using an optical fin 10 having a core 12 and a clad 14.
  • the surface of the clad 14 is a grating. It is preferable to use an optical fiber covered with (shown). Because coated optical fibers are stronger than uncoated optical fibers, they are less likely to be damaged during the manufacturing process.
  • the core 12 of the optical fiber 10 is formed of a material exhibiting a photo-induced refractive index change.
  • the core 12 it is preferable to use the same concentration of Ge as that of the normal specification optical fiber and the addition of Sn, or 31 and 81, or the dopant of Sn, A1, and B. It is preferable to constantly increase the change.
  • the ordinary specification optical fiber is an optical fiber to be connected to the optical fiber 10, and such an optical fiber has a relative refractive index difference of 0.9% with respect to its core. It is manufactured by doping a certain amount of Ge.
  • the core 12 of the optical fiber 10 has Ge in the same amount as that of the core of the optical fiber of the above-mentioned normal specification (an amount having a relative refractive index difference of 0.9%), and a concentration of 10,000 ppm.
  • Sn having a concentration of 10 000 to 15 000 ppm, or Sn having such a concentration and A1 having a concentration of 1,000 pm or less may be co-doped.
  • the above dope may be carried out by various known methods, for example, when carried out by immersion, the compound of the above Ge and S n (the case of S n, e.g., S n C 1 2 '2 H 2 0) of methyl It is performed by mixing with alcohol and immersing it in the solution.
  • a predetermined region of the prepared optical fiber 10 By irradiating a predetermined region of the prepared optical fiber 10 with ultraviolet laser light from outside the coating layer through, for example, a phase mask 22, a predetermined region of the core 12 of the optical fiber 10 is irradiated in the fiber axial direction.
  • the grating 20 having the first period (basic period or short period) is written in the buffer (Fig. 6 (a)).
  • a silica glass fiber (diameter: 125 jum) co-doped with Ge and Sn (Sn concentration: 15; OOO ppm) with a coating thickness of about 37.5 ⁇ m (Single layer: about 75 zm on both sides) Coated optical fiber (coated outer diameter about 20 O jum) is used.
  • the coating layer (not shown) is made of an aliphatic urethane acrylate having a transmittance of about 10% or more for ultraviolet rays having a wavelength of about 240 nm to about 270 nm (photoinitiator: 2, 4, 6,, — It is formed by UV curing of trimethylbenzoyldiphenylphosphine oxide).
  • the coated optical fiber 10 was left in a high-pressure hydrogen gas of about 20 MPa for about 2 weeks, and a hydrogen filling treatment was performed. gave.
  • Grading was written by sweeping (about 22 mm) coherent ultraviolet laser light (1 OmW) of 266 ⁇ m, which is the fourth harmonic (4 ⁇ ) of Nd-YAG laser light. Execute.
  • the writing of the grating can be performed by a known method, and is not limited to the method using the phase mask 22.
  • the first periodic structure (grating) 20 thus formed on the core 12 has a refractive index distribution as shown in FIG. 7A along the longitudinal direction of the fiber. This is the same as the refractive index distribution in a conventional optical fiber grating having a single periodic structure.
  • a second periodic structure for modulating the previously formed first periodic structure (grating) 20 is formed so as to overlap the grating 20 (FIG. 6 (b)).
  • the writing process of the second periodic structure can be performed in substantially the same manner as the writing process of the first periodic structure just by changing the pitch of the mask 32 used for ultraviolet irradiation.
  • an intensity modulation mask may be used instead of the phase difference mask 32.
  • the second period ⁇ 2 1 0. 6 5 / m , i.e. the modulation parameter Isseki p and 2 0.
  • the refractive index changes continuously (for example, according to a sine function) as shown in FIG.
  • the line width (half-value width) of the side band is reduced, which is preferable.
  • the shape of the periodic structure of the refractive index change can be changed to various shapes other than the exemplified rectangular wave and sine wave by adjusting the structure of the phase mask or the intensity modulation mask.
  • Superimposing the second periodic structure on the first periodic structure 20 means that the second periodic structure overlaps at least a part of the first periodic structure 20, The second periodic structures do not need to overlap. If at least one cycle of the second cycle is superimposed on the first cycle structure, the effect of modulation by the double cycle structure can be obtained. In order to sufficiently obtain the effect of the modulation of the first periodic structure 20 by the second periodic structure, it is preferable that the ranges of about 50% overlap.
  • a hydrogen diffusion process may be performed in order to increase the photoinduced refractive index change.
  • the grating 30 on which the second periodic structure is written has a refractive index distribution along the longitudinal direction of the fiber as shown in FIG. 7 (b).
  • the obtained optical fiber grating has the first wavelength (1.545 ⁇ m) corresponding to the first period, and the two wavelengths generated on both sides. Band (1.59 1m at the second wavelength, 1.585 ⁇ m at the third wavelength).
  • the second side band of the fourth wavelength 1.474 m and the fifth wavelength 1.627 m are also provided. Light is also reflected.
  • an optical fiber grating 30 having a double refractive index structure is actually manufactured, and the optical fiber grating 30 includes light of a first wavelength corresponding to the first periodic structure (short-period structure) and It was confirmed that the first periodic structure selectively reflected light in two sidebands (second and third wavelengths) resulting from modulation by the second periodic structure (long-period structure).
  • the double periodic structure shown in FIG. 7B is strictly different from the model double periodic structure shown in FIG. That is, the refractive index of the region where the core refractive index should not change in the first period structure (the low refractive index region in the short period structure) changes in the second period.
  • a separate manufacturing method was used in which the first periodic structure (short-period grating) was written and then the second periodic structure (long-period grating) was written.
  • a side band having a practical level of reflectivity is generated in most cases.
  • the core refractive index should change in the first periodic structure.
  • Fig. 6 (c) as an ideal method to form an ideal multiplex structure in which the refractive index of the low refractive index region is constant and only the refractive index of the high refractive index region
  • the mask 22 for writing the grating in the first cycle and the mask 32 for writing the grating in the second cycle are overlapped and irradiated with ultraviolet light, so that the first cycle and the second cycle can be performed in a single process.
  • a method of writing periodic gratings is conceivable.
  • a mask in which the first period mask 22 and the second period mask 32 are integrally formed may be used.
  • the wavelength bands in which the sidebands are generated can be predicted based on equation (1) or (2) above.
  • the desired refractive index multi-periodic structure element can be obtained by using the following method. Can be manufactured.
  • the values of the parameters (refractive index, fundamental period, modulation parameters, etc.) on the right side of the above equation are set as appropriate, and the transfer matrix is obtained from the obtained refractive index multiplexed structure (£ a (i) in the above equation).
  • the wavelength band (calculated value) of the side band is obtained using the method.
  • the basic design of the desired refractive index multi-periodic structure element preliminary determination of the parameters by resetting the values of the above parameters so as to obtain the side bands of the desired wavelength band. I do.
  • a multi-period grating is actually produced based on the parameters determined in advance according to the above design method.
  • the measured values of the wavelength bands of the actually manufactured gray sidebands are compared with the target values, and the preliminary set parameters are corrected based on the comparison results.
  • the manufacturing conditions (mask period, UV illuminance, etc.) are changed based on the corrected parameters, and a multi-period grating is actually produced again.
  • the target value of the side band wavelength band is compared with the measured value, and the above process is repeated until the difference between the target value and the measured value falls within an allowable range, thereby obtaining a desired refractive index multiple period.
  • a structural element is obtained.
  • the first cycle (short cycle) is 0.53225 nm
  • the second cycle (long cycle) is 20.2.85
  • ⁇ m 1 / about 400
  • p 1 / about 400
  • the irradiation condition of the ultraviolet light is such that in the writing process of the first periodic structure, the laser light is reciprocally scanned in a range of about 25 mm along the longitudinal direction of the fiber in one reciprocation, and the writing process of the second periodic structure is:
  • the above laser beam was irradiated for 10 minutes to a range of 20 mm through a predetermined mask.
  • the obtained optical fiber grating having the refractive index double period structure has the first wavelength (1.5 4 284 zm) corresponding to the first period. ), And both sides selectively reflect the light of the two generated side bands (second wavelength 1.5 384 1111, third wavelength 1.5 468 4 ⁇ m).
  • the modulation parameter p of the optical fiber grating of the second embodiment is about 200, which is larger than the modulation parameter p of the optical fiber grating of the first embodiment, so that the first wavelength and the sideband ( The difference between the second and third wavelengths is also smaller in the optical fiber grating of the first embodiment.
  • a one-dimensional multi-periodic structure has been exemplified as the permittivity multi-periodic structure, but the present invention can also be applied to a two-dimensional or three-dimensional multi-periodic structure. That is, the present invention provides a multi-periodic structure in which periodic structures whose permittivity changes along the first direction (the core propagation direction in the above example) are superimposed on each other, and a second direction different from the first direction. Element having a multi-periodic structure in which the periodic structures of which permittivity changes along the two-dimensional structure, and a periodic structure in which the permittivity changes along the third direction different from the first and second directions are superimposed on each other. It can be applied to a three-dimensional element further having a multi-periodic structure. These multi-dimensional elements can be used for optical multiplexing communication because they can confine or reflect light of different wavelengths in any direction and at any position, and reflect them. You.
  • an optical fiber grating having a two-dimensional dielectric constant multiperiod structure has a refractive index along the direction (radial direction of the fiber) perpendicular to the core propagation direction (fiber axis direction) when fabricating a fiber core. It can be manufactured by forming a multiplex structure and forming a refractive index multiplex structure along the core propagation direction on the core using the method described in the above embodiment.
  • Specific methods for forming a multiple refractive index structure in a direction perpendicular to the core propagation direction include, for example, a multi-periodic film deposition method, a multi-period insertion method of a heterogeneous substance, a multi-period etching, and a multi-period cutting method.
  • the optical waveguide corresponding to the optical fiber grating having the two-dimensional refractive index multiperiodic structure can be used for a planar optical circuit.
  • an optical circuit having a three-dimensional dielectric constant multiperiodic structure can be manufactured.
  • the structure and operation of the multiple dielectric constant periodic structure element according to the present invention have been described using an optical fiber grating as an example.
  • the present invention is not limited to this. If an element having a structure is formed, it can be applied to electromagnetic waves in other wavelength ranges. For example, it is possible to configure an element that confines an electromagnetic wave having a relatively long wavelength, such as a submillimeter wave or a quasi-millimeter wave, or reflects an electromagnetic wave in a specific direction with good directivity.
  • a dielectric constant multi-periodic structure element capable of realizing an element or the like that selectively reflects a plurality of electromagnetic waves having different wavelength bands from each other, a method for designing the same, and a method for manufacturing the same.
  • an optical fiber grating having a refractive index multiperiodic structure capable of selectively reflecting a plurality of light beams having different wavelengths in a narrow band can be obtained.
  • the optical fiber grating according to the present invention is suitably used for wavelength division multiplex communication.

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  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Light Guides In General And Applications Therefor (AREA)
  • Optical Integrated Circuits (AREA)
  • Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)
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Abstract

L'invention concerne un dispositif à structures périodiques multiples de constante diélectrique possédant une première structure périodique dont la constante diélectrique varie avec un premier pas périodique Μ1, dans une première direction, et une deuxième structure périodique, sur la première structure périodique, dont la constante diélectrique varie avec un deuxième pas périodique Μ2 plus long que le premier pas périodique Μ1 dans la première direction. L'une au moins des première et deuxième structures périodiques est comprimée. Dans une autre réalisation, le dispositif comprend une troisième structure périodique dont la constante diélectrique varie avec un troisième pas périodique Μ3 dans une deuxième direction différente de la première direction et une quatrième structure périodique, sur la troisième structure périodique, dont la constante diélectrique varie dans la deuxième direction selon un quatrième pas périodique Μ4 plus long que le troisième pas périodique Μ3.
PCT/JP2001/000781 2000-02-04 2001-02-02 Dispositif a structures periodiques multiples de constante dielectrique, et procedes de conception et de production associes WO2001057567A1 (fr)

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JP2000-027041 2000-02-04
JP2000027041A JP2001215351A (ja) 2000-02-04 2000-02-04 誘電率多重周期構造素子およびその設計方法ならびに製造方法

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WO2001057567A1 true WO2001057567A1 (fr) 2001-08-09

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GB2390230B (en) 2002-06-07 2005-05-25 Murata Manufacturing Co Applications of a three dimensional structure

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Publication number Priority date Publication date Assignee Title
US8554038B2 (en) 2010-01-29 2013-10-08 Furukawa Electric Co., Ltd. Manufacturing method of photonic band gap fiber and photonic band gap fiber

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