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WO2018150813A1 - Coupleur optique et procédé de couplage optique - Google Patents

Coupleur optique et procédé de couplage optique Download PDF

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Publication number
WO2018150813A1
WO2018150813A1 PCT/JP2018/001721 JP2018001721W WO2018150813A1 WO 2018150813 A1 WO2018150813 A1 WO 2018150813A1 JP 2018001721 W JP2018001721 W JP 2018001721W WO 2018150813 A1 WO2018150813 A1 WO 2018150813A1
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WO
WIPO (PCT)
Prior art keywords
optical
light
input light
optical coupler
propagation axis
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PCT/JP2018/001721
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English (en)
Japanese (ja)
Inventor
毅 小西
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国立大学法人大阪大学
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Application filed by 国立大学法人大阪大学 filed Critical 国立大学法人大阪大学
Priority to JP2018568058A priority Critical patent/JP7141708B2/ja
Publication of WO2018150813A1 publication Critical patent/WO2018150813A1/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
    • 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
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/34—Optical coupling means utilising prism or grating

Definitions

  • the present invention relates to coupling of light to an optical waveguide.
  • an optical coupler that couples light to the optical waveguide by condensing the light on the end face of the core of the optical waveguide (for example, optical fiber, silicon waveguide (silicon photonics), etc.) has been used.
  • a lens or a tapered waveguide is used for condensing light onto the end face of the core of the optical waveguide.
  • the rod lens is provided in the end surface of the optical fiber.
  • optical damage since incident light is condensed on the end surface of a core, an optical damage may be caused to the end surface of a core.
  • the optical damage threshold per unit area of the core surface of the optical fiber is about 250 kW / cm 2 . Therefore, when high-intensity light exceeding 0.5 W is coupled to a single mode optical fiber having a core diameter of about 10 ⁇ m, optical damage occurs on the end face of the core.
  • the present invention provides an optical coupler capable of suppressing optical damage of the optical waveguide due to optical coupling and improving optical coupling efficiency.
  • An optical coupler is an optical coupler that couples input light to an optical waveguide, the optical coupler including a region having a diffractive optical function formed in a core of the optical waveguide, Enters the region having the diffractive optical function from a direction perpendicular to the propagation axis of the optical waveguide.
  • the input light can be coupled to the optical waveguide by making the input light incident on the diffractive optical element from a direction perpendicular to the propagation axis of the optical waveguide. Therefore, since it is not necessary to focus the input light on the end face of the core, it becomes possible to match the intensity distribution of the input light with the mode distribution of the optical waveguide by the region having the diffractive optical function, thereby improving the optical coupling efficiency. Can do. In addition, since it is not necessary to collect input light on the end face of the core, optical damage to the core can be suppressed.
  • the diffractive optical element is formed inside the core, the optical coupling efficiency can be obtained no matter what direction the input light is incident on the region having the diffractive optical function from any direction as long as it is in a plane perpendicular to the propagation axis of the optical waveguide.
  • the input light can be coupled to the optical waveguide while suppressing the variation of the above, and the degree of freedom of the environment in which the optical coupler is used can be increased.
  • the optical coupler can be used even in an environment (for example, a light receiving portion of a microscope) in which restrictions on the installation location of the optical coupler are severe.
  • the region having the diffractive optical function may satisfy a Bragg condition for the input light incident from a direction perpendicular to the propagation axis of the optical waveguide.
  • the diffraction efficiency in the direction parallel to the propagation axis of the optical waveguide can be improved, and the optical coupling efficiency can be improved.
  • the direction perpendicular to the propagation axis of the optical waveguide is a direction within a predetermined angular range from a direction strictly perpendicular to the propagation axis of the optical waveguide, and the predetermined angular range is a coupled wave. It may be in a range where the diffraction efficiency is 0.5 or more in theory (coupled-wave theory).
  • input light can be incident on a region having a diffractive optical function within an angular range where the diffraction efficiency is 0.5 or more, and the optical coupling efficiency is improved while allowing a certain amount of error. be able to.
  • the region having the diffractive optical function may be a fiber Bragg grating.
  • a fiber Bragg grating can be used for the diffractive optical element.
  • the fiber Bragg grating is most commonly used in an optical fiber sensor, and an optical coupler can be realized relatively easily.
  • the lattice constant of the fiber Bragg grating may coincide with the wavelength of the input light.
  • the lattice constant of the fiber Bragg grating can be matched with the wavelength of the input light. Therefore, the traveling direction of the diffracted light can be made closer to the direction parallel to the propagation axis of the optical waveguide, and the optical coupling efficiency can be further improved.
  • the optical coupler may further include an input unit that makes the input light incident on a region having the diffractive optical function from a direction perpendicular to the propagation axis.
  • the optical coupler can include an input unit that inputs the input light to the diffractive optical element from a direction perpendicular to the propagation axis of the optical waveguide.
  • the input light can be reliably incident on the diffractive optical element, and the optical coupling efficiency can be improved.
  • the input unit may include a condensing element that condenses the input light in a linear shape extending in a direction parallel to the propagation axis.
  • a condensing element that condenses input light in a linear shape extending in a direction parallel to the propagation axis can be used as the input unit. Therefore, the input light can be condensed linearly along the diffractive optical element formed in the core. As a result, the input light can be reliably incident on the diffractive optical element, and the optical coupling efficiency can be further improved.
  • the input unit includes a dispersive element that disperses the input light in a direction parallel to the propagation axis, and the distribution of the lattice constant of the fiber Bragg grating is dispersed in the direction parallel to the propagation axis. It may correspond to the wavelength distribution of the input light.
  • a dispersive element that disperses input light in a direction parallel to the propagation axis can be used as the input unit. Furthermore, in the direction parallel to the propagation axis, the distribution of the fiber Bragg grating lattice constant can be made to correspond to the distribution of the wavelength of the dispersed input light. Therefore, even for broadband input light, the wavelength of the input light can match the lattice constant of the fiber Bragg grating, and the shift between the traveling direction of the diffracted light and the direction of the propagation axis of the optical fiber can be reduced. Can do. That is, even for broadband input light, the diffracted light can be adapted to the mode of the optical fiber with higher accuracy, and the optical coupling efficiency can be improved.
  • the optical coupler may further include an adjustment unit that adjusts a lattice constant of the fiber Bragg grating according to the wavelength of the input light.
  • the fiber Bragg grating lattice constant can be adjusted according to the wavelength of the input light. Therefore, the range of wavelengths of input light that can be coupled can be expanded, and the versatility of the optical coupler can be improved.
  • the optical coupler may further include a reflecting unit that reflects one of the lights diffracted in two directions parallel to the propagation axis by the region having the diffractive optical function in opposite directions.
  • the light propagating through the core can be reflected. Therefore, one of the diffracted lights diffracted in both directions of the propagation axis can be reflected and combined with the other, and the optical coupling efficiency can be improved.
  • the optical coupler may further include a phase compensation unit that compensates a phase of light coupled to the core by the region having the diffractive optical function.
  • the phase of light coupled to the core can be compensated. Therefore, the phase shift of the combined light can be compensated, and for example, when the input light is pulsed light, a change in waveform due to optical coupling can be suppressed.
  • the optical waveguide may be an optical fiber.
  • input light can be coupled to the optical fiber.
  • the optical coupling method is an optical coupling method for coupling input light to an optical waveguide, and is formed inside the core of the optical waveguide from a direction perpendicular to the propagation axis of the optical waveguide.
  • the optical coupler according to one embodiment of the present invention can suppress optical damage of the optical waveguide due to optical coupling and improve optical coupling efficiency.
  • FIG. 1 is a perspective view showing the configuration of the optical coupler according to Embodiment 1.
  • FIG. 2 is a diagram illustrating light diffraction by a general diffraction grating having a lattice constant d.
  • FIG. 3 is a flowchart showing an optical coupling method using the optical coupler according to the first embodiment.
  • FIG. 4A is a diagram showing an outline of an optical coupling experiment.
  • FIG. 4B is a graph showing the relationship between the incident angle and the intensity of the combined light in the optical coupling experiment.
  • FIG. 5 is a perspective view showing the configuration of the optical coupler according to the second embodiment.
  • FIG. 6 is a perspective view showing the configuration of the optical coupler according to Embodiment 3.
  • FIG. 7 is a diagram illustrating a simulation model and a simulation result of the optical coupler according to the third embodiment.
  • FIG. 8A is a graph showing the relationship between the core diameter and the optical coupling efficiency in the simulation result of the optical coupler according to Embodiment 3.
  • FIG. 8B is a graph showing the relationship between the core diameter and the optical damage threshold in the simulation result of the optical coupler according to Embodiment 3.
  • FIG. 9 is a side view showing the configuration of the optical coupler according to the fourth embodiment.
  • FIG. 10 is a side view illustrating the configuration of the optical coupler according to the fifth embodiment.
  • FIG. 11 is a side view showing the configuration of the optical coupler in accordance with the sixth embodiment.
  • coincidence, vertical and parallel are used, but unless specifically limited, these are not strict and are used in a substantial sense.
  • “match” not only means that they are completely matched, but also includes a range that can be considered to be substantially matched. That is, “match” allows an error of about several percent.
  • vertical means not only strictly vertical but also includes a range that can be regarded as substantially vertical.
  • parallel not only means strictly parallel, but also includes a range that can be regarded as substantially parallel.
  • FIG. 1 is a diagram illustrating a configuration of the optical coupler according to the first embodiment.
  • the X-axis direction is a direction parallel to the propagation axis of the optical fiber
  • the Y-axis direction and the Z-axis method are directions orthogonal to the propagation axis of the optical fiber.
  • the optical fiber 100 is an example of an optical waveguide and is a medium for transmitting an optical signal.
  • the optical fiber 100 is a single mode optical fiber and includes a core 110 and a cladding 120.
  • the core 110 is made of, for example, quartz glass or plastic, and is surrounded by the clad 120.
  • the diameter of the core 110 is, for example, about 10 ⁇ m to 100 ⁇ m.
  • the clad 120 is made of, for example, quartz glass or plastic, and has a lower refractive index than the core 110.
  • the outer diameter of the clad 120 is, for example, about 30 ⁇ m to 500 ⁇ m.
  • a region having a diffractive optical function (hereinafter referred to as a diffractive optical element 10) is formed inside the core 110.
  • the input light 130 enters the diffractive optical element 10 from a direction perpendicular to the propagation axis of the optical fiber 100 (Z-axis direction in FIG. 1).
  • the input light 130 is diffracted by the diffractive optical element 10.
  • the diffracted light 140a and 140b also referred to as coupled light propagates in a direction parallel to the propagation axis (X-axis direction in FIG. 1).
  • the direction perpendicular to the propagation axis of the optical fiber 100 may be a direction within a predetermined angle range from a direction strictly perpendicular to the propagation axis of the optical fiber 100.
  • This predetermined angle range can be defined based on the coupled wave theory described in Non-Patent Document 1.
  • the predetermined angular range may be a range in which the diffraction efficiency is equal to or higher than a predetermined threshold efficiency in the coupled wave theory.
  • a predetermined threshold efficiency for example, 0.5 can be used, preferably 0.6 can be used, and more preferably 0.7 can be used. If a value equal to or greater than 0.5 is used as the predetermined threshold efficiency, it is possible to realize a higher coupling efficiency than before.
  • the diffractive optical element 10 satisfies the Bragg condition for the input light 130 incident from a direction perpendicular to the propagation axis of the optical fiber 100.
  • the Bragg condition is expressed by Equation 1 below.
  • d represents the lattice constant of the diffractive optical element 10
  • ⁇ represents the angle formed by the propagation axis of the optical fiber 100 and the input light 130
  • ⁇ represents the wavelength of the input light 130
  • n represents an integer.
  • the diffractive optical element 10 is a fiber Bragg grating (FBG).
  • the FBG is manufactured by, for example, irradiating an optical fiber with ultraviolet laser light and periodically changing the refractive index inside the core having sensitivity to ultraviolet light in a direction parallel to the propagation axis.
  • the lattice constant d of the diffractive optical element 10 matches the wavelength ⁇ of the input light 130.
  • the propagation direction of the input light 130 is converted from the incident direction (Z-axis direction in FIG. 1) to a direction perpendicular to the incident direction (X-axis direction in FIG. 1).
  • FIG. 2 is a diagram illustrating light diffraction by a general diffraction grating having a lattice constant d.
  • d a lattice constant
  • FIG. 2 when light of wavelength ⁇ is incident on the diffraction grating at angle ⁇ 1 , diffracted light of angle ⁇ 2 is generated. Since the wavefront phases of the incident light and the diffracted light are equal, the following Expression 2 is established for the + 1st order and ⁇ 1st order diffracted lights.
  • the incident direction of the input light 130 is not limited to the Z-axis direction.
  • the input light 130 may be incident on the diffractive optical element 10 from a direction perpendicular to the X-axis direction (for example, the Y-axis direction). Even in this case, the diffracted lights 140a and 140b travel in the positive and negative directions in the X-axis direction based on the above equation 2.
  • FIG. 3 is a flowchart showing the optical coupling method according to the first embodiment.
  • the input light 130 having a wavelength that matches the lattice constant is incident on the diffractive optical element 10 formed inside the core 110 of the optical fiber 100 (S110).
  • the input light 130 is diffracted by the diffractive optical element 10 (S120). That is, the input light 130 is converted into diffracted light 140 a and 140 b that propagates in a direction parallel to the propagation axis of the optical fiber 100.
  • the input light 130 is incident on the diffractive optical element 10 from the direction perpendicular to the propagation axis of the optical fiber 100 (for example, the Z-axis direction). Input light 130 can be coupled to the fiber 100. Accordingly, since it is not necessary to collect the input light 130 on the end face of the core 110, the intensity distribution of the input light 130 can be matched with the mode distribution of the optical fiber 100 by the diffractive optical element 10, and the optical coupling efficiency is improved. Can be made. In addition, since it is not necessary to collect the input light 130 on the end face of the core 110, optical damage to the core 110 can be suppressed.
  • the diffractive optical element 10 is formed inside the core 110, the input light 130 is transmitted from which direction (for example, the Y-axis direction and the Z-axis direction) 360 degrees within a plane perpendicular to the propagation axis of the optical fiber 100. Even if the light enters the diffractive optical element 10, the input light 130 can be coupled to the optical fiber 100 while suppressing variations in optical coupling efficiency, and the degree of freedom of the environment in which the optical coupler is used can be increased. As a result, the optical coupler according to the present embodiment can be used even in an environment (for example, a light receiving part of a microscope) in which restrictions on the installation location of the optical coupler are severe.
  • an environment for example, a light receiving part of a microscope
  • the diffractive optical element 10 can satisfy the Bragg condition for the input light 130 incident from a direction perpendicular to the propagation axis of the optical fiber 100. Therefore, the diffraction efficiency of the input light 130 in the direction parallel to the propagation axis of the optical fiber 100 can be improved, and the optical coupling efficiency can be improved.
  • the input light can be incident on the region having the diffractive optical function within an angle range where the diffraction efficiency is 0.5 or more, and a certain amount of error is allowed.
  • the optical coupling efficiency can be improved.
  • FBG can be used for the diffractive optical element 10.
  • the FBG is most commonly used in an optical fiber sensor, and the diffractive optical element 10 can be formed in the core 110 relatively easily. Therefore, the optical coupler according to the present embodiment can be realized relatively easily.
  • the lattice constant of the FBG can be matched with the wavelength of the input light. Therefore, the traveling direction of the diffracted light can be made closer to the direction parallel to the propagation axis of the optical fiber 100, and the optical coupling efficiency can be further improved.
  • FIG. 4A is a diagram showing an outline of an optical coupling experiment.
  • a slab waveguide was used as the optical waveguide as shown in FIG. 4A.
  • a diffraction grating film sheet was used as the core and the diffractive optical element formed inside the core.
  • the thickness of the diffraction grating film sheet was about 120 ⁇ m, and the lattice constant was 1.0 ⁇ m.
  • a glass plate was used as the cladding.
  • the wavelength of the input light incident on the slab waveguide from the light source was about 1.6 ⁇ m. Since the refractive index of the diffraction grating film sheet is high, input light having a wavelength of 1.6 ⁇ m, which is slightly larger than the lattice constant of 1.0 ⁇ m, was used. Input light was incident on such a slab waveguide at a plurality of incident angles ⁇ , and the intensity of the coupled light was measured with an intensity measuring device at each of the plurality of incident angles.
  • FIG. 4B is a graph showing the relationship between the incident angle and the intensity of the coupled light in the optical coupling experiment.
  • the intensity of the coupled light was highest when the incident angle ⁇ was near 90 degrees.
  • the optical coupling efficiency was 90% or more. That is, when the input light is incident on the diffractive optical element from a direction perpendicular to the propagation axis, the input light can be coupled to the waveguide with high optical coupling efficiency.
  • the optical coupler includes a condensing element that condenses input light in a linear shape extending in a direction parallel to the propagation axis of the optical waveguide.
  • the optical coupler according to the present embodiment will be described in detail with reference to the drawings, centering on differences from the first embodiment.
  • FIG. 5 is a perspective view showing the configuration of the optical coupler according to the second embodiment.
  • the optical coupler according to the present embodiment includes a condensing element 20 in addition to the diffractive optical element 10.
  • the condensing element 20 is an example of an input unit that inputs the input light 131a to the diffractive optical element 10 from a direction perpendicular to the propagation axis of the optical fiber 100, and is, for example, a cylindrical lens.
  • the condensing element 20 condenses the input light 131a in a linear shape extending in a direction parallel to the propagation axis of the optical fiber 100 (X-axis direction).
  • the linear light 131b enters the diffractive optical element 10 from a direction perpendicular to the propagation axis of the optical fiber 100 (Z-axis direction).
  • the condensing element 20 that condenses the input light 131a in a linear shape extending in a direction parallel to the propagation axis (X-axis direction) can be provided. . Therefore, the input light 131a can be condensed linearly along the diffractive optical element 10 formed on the core 110 (linear light 131b). As a result, the input light 131a can be reliably incident on the diffractive optical element 10, and the optical coupling efficiency can be further improved.
  • Embodiment 3 Next, Embodiment 3 will be described.
  • the present embodiment is mainly different from the first embodiment in that the reflection portion formed on the end face of the core is included in the optical coupler.
  • the optical coupler according to the present embodiment will be described in detail with reference to the drawings, centering on differences from the first embodiment.
  • FIG. 6 is a perspective view showing the configuration of the optical coupler according to Embodiment 3.
  • the optical coupler according to the present embodiment includes a reflecting unit 30 in addition to the diffractive optical element 10.
  • the reflection unit 30 is provided on the end surface of the core 110, and reflects the diffracted light 140a propagating through the core 110 toward the reflection unit 30. That is, the reflecting unit 30 is one of the light (diffracted light 140a and 140b in the present embodiment) diffracted by the diffractive optical element 10 in two directions parallel to the propagation axis (diffracted light 140a in the present embodiment). ) Is reflected in the opposite direction. As a result, the traveling direction of the diffracted light 140a is reversed, and the diffracted light 140a is combined with the diffracted light 140b.
  • the reflection unit 30 reflects the light propagating in the negative direction in the X-axis direction in the positive direction in the X-axis direction.
  • the reflection part 30 is a metal film (for example, aluminum etc.) which covers the end surface of the core 110, for example.
  • the light propagating through the core 110 can be reflected by the end face of the core 110. Therefore, one (diffracted light 140a) of the diffracted light diffracted in both directions of the propagation axis can be combined with the other (diffracted light 140b), and the optical coupling efficiency can be improved.
  • FIG. 7 is a diagram illustrating a simulation model and a simulation result of the optical coupler according to the third embodiment.
  • FIG. 7A is a perspective view of a three-dimensional model of the optical coupler in the simulation.
  • FIG. 7B is a cross-sectional view of the three-dimensional model of the optical coupler in the simulation.
  • FIGS. 7C and 7D are diagrams showing light intensity distributions after 130 femtoseconds and 1000 femtoseconds in the cross section shown in FIG. 7B. 7C and 7D show that the closer to white, the higher the light intensity, and the closer to black, the lower the light intensity.
  • a finite element time difference method (FDTD) is used, and a linear (two-dimensional) input light from a light source is a propagation axis of an optical fiber as shown in FIG.
  • the light was incident on the diffractive optical element formed inside the core through the clad from the direction perpendicular to.
  • the length in the direction of the propagation axis of the core region (that is, the region where the diffractive optical element is formed) on which the input light is incident was set to 1 cm.
  • a reflection portion was provided on one end face of the core, the wavelength of the input light was 1.485 ⁇ m, and the lattice constant of the diffractive optical element was 1 ⁇ m.
  • the input light incident on the diffractive optical element from the direction perpendicular to the propagation axis of the optical fiber has been converted by the diffractive optical element into coupled light traveling in a direction parallel to the propagation axis. I understand.
  • FIG. 8A is a graph showing the relationship between the core diameter and the optical coupling efficiency.
  • FIG. 8B is a graph showing the relationship between the core diameter and the intensity of input light causing optical damage. In FIG. 8B, 250 kW / cm 2 was used as the optical damage threshold.
  • FIG. 8A shows that an optical coupling efficiency of 60% or more can be realized at a core diameter of 10 ⁇ m or more.
  • FIG. 8B shows that input light having a higher intensity than that of the prior art can be coupled to the optical fiber without optical damage.
  • this simulation shows that the optical coupler according to the present embodiment can achieve high optical coupling efficiency and can increase the intensity of input light that can be coupled without optical damage as compared with the prior art. It was.
  • the optical coupler includes a dispersive element that disperses input light in a direction parallel to the propagation axis of the optical waveguide.
  • the optical coupler according to the present embodiment will be described in detail with reference to the drawings, centering on differences from the first embodiment.
  • FIG. 9 is a side view showing the configuration of the optical coupler according to the fourth embodiment.
  • the optical coupler according to the present embodiment includes a diffractive optical element 11, a dispersion element 40, and a lens 41.
  • the dispersion element 40 is an example of an input unit that inputs the input light 132a to the diffractive optical element 11 from a direction perpendicular to the propagation axis of the optical fiber 100, and is, for example, a diffraction grating.
  • the dispersion element 40 disperses the input light 132a in a direction (X-axis direction) parallel to the propagation axis of the optical fiber 100. That is, the dispersive element 40 separates the input light 132a at different positions in the X-axis direction according to the frequency of the input light 132a.
  • the dispersed light 132b includes, for example, red dispersed light 132bR, green dispersed light 132bG, and blue dispersed light 132bB.
  • the lens 41 refracts the dispersed light 132b from the dispersion element 40 and makes the dispersed light 132b enter the diffractive optical element 11 from a direction perpendicular to the propagation axis of the optical fiber 100 (Z-axis direction).
  • the diffractive optical element 11 is an FBG.
  • the distribution of the lattice constant of the FBG corresponds to the wavelength distribution of the dispersed light 132b. That is, the lattice constant of the FBG continuously changes in the X-axis direction so that the wavelength of the dispersed light 132b incident on the FBG matches the lattice constant of the FBG.
  • the lattice constant of the region where the red dispersed light 132bR is incident is larger than the lattice constant of the region where the blue dispersed light 132B is incident.
  • the dispersive element 40 that disperses the input light 132a in the direction parallel to the propagation axis (X-axis direction) can be provided. Furthermore, in the direction parallel to the propagation axis (X-axis direction), the distribution of the lattice constant of the FBG can correspond to the wavelength distribution of the dispersed light 132b. Therefore, even for broadband input light, the wavelength of the dispersed light 132b and the lattice constant of the FBG can be matched with high accuracy, and the deviation between the traveling direction of the diffracted light and the direction of the propagation axis of the optical fiber is reduced. can do. That is, even for broadband input light, the diffracted light can be adapted to the mode of the optical fiber 100 with higher accuracy, and the optical coupling efficiency can be improved.
  • the optical coupler according to the present embodiment includes a phase compensator for compensating for a phase shift due to wavelength.
  • FIG. 10 is a side view illustrating the configuration of the optical coupler according to the fifth embodiment.
  • the optical coupler according to the present embodiment includes a phase compensation unit 50 in addition to the diffractive optical element 10.
  • the phase compensation unit 50 compensates the phase of the light coupled to the core 110 by the diffractive optical element 10. That is, the phase compensation unit 50 compensates for the phase shift of the diffracted light due to the wavelength.
  • the phase compensation unit 50 includes an optical circulator 51 and an FBG 52.
  • the optical circulator 51 is a 3-port type optical circulator.
  • the optical circulator 51 guides light that has entered the optical circulator 51 from the optical fiber 100 to the optical fiber 101. Further, the optical circulator 51 guides the light that has entered the optical circulator 51 from the optical fiber 101 to the optical fiber 101. That is, the diffracted light 140 b from the diffractive optical element 10 is guided to the FBG 52, and the reflected light from the FBG 52 is guided to the optical fiber 102.
  • optical fibers 100, 101, and 102 may be referred to as first, second, and third optical fibers, respectively.
  • the FBG 52 is formed inside the core of the optical fiber 101.
  • the FBG 52 has a lattice constant that changes in the direction of the propagation axis of the optical fiber 101, and reflects light having a wavelength corresponding to the lattice constant at that position at each position in the direction of the propagation axis. That is, the optical path length in the optical fiber 101 differs depending on the wavelength of the diffracted light 140b. As a result, the phase shift of the diffracted light 140b is compensated.
  • the phase of the light coupled to the core 110 can be compensated. Therefore, the phase shift of the combined light can be compensated, and for example, when the input light is pulsed light, a change in waveform due to optical coupling can be suppressed.
  • Embodiment 6 Next, a sixth embodiment will be described.
  • the present embodiment is mainly different from Embodiment 1 in that an adjustment unit that adjusts the lattice constant of the FBG according to the wavelength of input light is included in the optical coupler.
  • an adjustment unit that adjusts the lattice constant of the FBG according to the wavelength of input light is included in the optical coupler.
  • the optical coupler according to the present embodiment will be described in detail with reference to the drawings, centering on differences from the first embodiment.
  • FIG. 11 is a side view showing the configuration of the optical coupler in accordance with the sixth embodiment. As shown in FIG. 11, the optical coupler according to the present embodiment includes an adjustment unit 60.
  • the adjusting unit 60 adjusts the lattice constant of the diffractive optical element 10 (FBG) according to the wavelength of the input light 130.
  • the adjustment unit 60 is a heater, and adjusts the lattice constant of the FBG by heating the optical fiber 100.
  • the adjustment unit 60 is an actuator, and adjusts the lattice constant of the FBG by applying an external force to the optical fiber 100.
  • the lattice constant of the FBG (diffractive optical element 10) can be adjusted according to the wavelength of the input light 130. Therefore, the range of wavelengths of input light that can be coupled can be expanded, and the versatility of the optical coupler can be improved.
  • optical coupler according to one or more aspects of the present invention has been described based on the embodiment, the present invention is not limited to this embodiment. Unless it deviates from the gist of the present invention, one or more of the present invention may be applied to various modifications that can be conceived by those skilled in the art, or forms constructed by combining components in different embodiments. It may be included within the scope of the embodiments.
  • both the light collecting element in the second embodiment and the dispersion element in the fourth embodiment may be included in the optical coupler. Thereby, further improvement in coupling efficiency can be expected.
  • both the dispersion element in the fourth embodiment and the phase compensation unit in the fifth embodiment may be included in the optical coupler. Therefore, even if the input light is a broadband pulse light, the input light can be coupled to the optical waveguide while suppressing a change in waveform.
  • the optical waveguide is an optical fiber.
  • the optical waveguide is not limited to an optical fiber.
  • the optical waveguide may be a silicon waveguide formed by silicon photonics.
  • the cladding of the optical waveguide may be replaced by an air layer.
  • the diffractive optical element is FBG.
  • the present invention is not limited to this.
  • the diffractive optical element may be realized by a hologram.
  • a hologram can be applied to a diffractive optical element will be described.
  • the amplitude transmittance H (x, y, z) of the hologram formed by the superposition (interference) of the reference wave A in (x, y, z) and the object wave A 0 (x, y, z) is This can be expressed by the following formula 3.
  • Equation 4 the first term (A1) represents straight light, the second term (A2) represents a direct image (virtual image), and the third term (A3) represents a conjugate image (real image). Therefore, by appropriately setting the reference wave A in (x, y, z) and the object wave A 0 (x, y, z), the traveling direction of the reproduced wave A in (x, y, z) Holograms can be formed that produce images and conjugate images directly in the vertical direction. In other words, the hologram formed inside the core is diffracted light that travels in a direction parallel to the propagation axis when input light (reproduced wave) is incident from a direction perpendicular to the propagation axis of the core. A direct image and a conjugate image) can be emitted.
  • the optical coupler includes the light condensing element, but the light condensing element is not necessarily provided.
  • the light condensing element is not necessarily provided.
  • the clad can collect the input light, and when the input light is not linear light, the optical coupling efficiency can be improved even when there is no condensing element.
  • the reflective portion is provided on the end surface of the core, but the reflective portion is not necessarily provided on the end surface of the core.
  • the reflecting portion may be an FBG formed inside the core. Even in this case, the diffracted light propagating through the core can be reflected in the opposite direction.
  • the same effect as that of the reflecting portion can be realized by using an optical coupler that couples two optical waveguides (optical fibers) to one optical waveguide (optical fiber).
  • the optical coupling efficiency increases as the diameter of the core on which the diffractive optical element is formed increases. Therefore, the diameter of the portion where the core diffractive optical element is formed (referred to as the first portion) may be larger than the diameter of the portion where the core diffractive optical element is not formed (referred to as the second portion). In this case, a tapered coupling portion may be formed between the first portion and the second portion. Thereby, the optical coupling efficiency can be further improved.
  • optical coupler according to one embodiment of the present invention can be used as an optical coupler for coupling input light to an optical fiber or the like.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Couplings Of Light Guides (AREA)
  • Optical Integrated Circuits (AREA)

Abstract

L'invention concerne un coupleur optique destiné à coupler une lumière d'entrée (130) à une fibre optique (100), pourvu d'un élément optique de diffraction (10) formé dans un noyau (110) de la fibre optique (100), la lumière d'entrée (130) venant frapper l'élément optique de diffraction (10) à partir d'une direction perpendiculaire à l'axe de propagation de la fibre optique (100).
PCT/JP2018/001721 2017-02-14 2018-01-22 Coupleur optique et procédé de couplage optique WO2018150813A1 (fr)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111929778A (zh) * 2020-07-20 2020-11-13 西安立芯光电科技有限公司 一种半导体激光合束技术

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62109011A (ja) * 1985-11-06 1987-05-20 エイ・ティ・アンド・ティ・コーポレーション 単モ−ド光フアイバ用カツプリング装置および同装置を有する通信装置
JPH04288510A (ja) * 1989-12-26 1992-10-13 United Technol Corp <Utc> 光を反射させる埋め込み型ブラッグ回折格子を有する光導波路構成と埋め込み型ブラッグ回折格子を有する光導波路及びその製法
JPH11284263A (ja) * 1998-01-30 1999-10-15 Hitachi Cable Ltd 超広帯域波長分散補償デバイス，およびそれを用いた光通信システム
JP2005241712A (ja) * 2004-02-24 2005-09-08 Fujitsu Ltd 光合波方法および光合波器、並びに、それを用いた光増幅器
US20060013527A1 (en) * 2004-07-15 2006-01-19 Yannick Morel Optical distribution system for sensors
US7289700B1 (en) * 2006-05-19 2007-10-30 United States Of America As Represented By The Secretary Of The Navy Blazed grating optical fiber polarizing coupler
JP2012098513A (ja) * 2010-11-02 2012-05-24 Kyoto Institute Of Technology 波長選択フィルタ及びそれを備えたフィルタ装置及びレーザ装置

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5832156A (en) * 1996-10-31 1998-11-03 Lucent Technologies Inc. Article comprising an optical waveguide tap
SE514512C2 (sv) * 1999-07-02 2001-03-05 Proximion Fiber Optics Ab Förfarande och anordning för koppling av ljus
AUPQ165599A0 (en) * 1999-07-15 1999-08-05 University Of Sydney, The Optical processing method and apparatus and products thereof
CN100345013C (zh) * 2004-11-19 2007-10-24 东南大学 含有光波导内嵌入式倾斜布拉格光栅的装置及光处理方法
US20150358081A1 (en) * 2014-06-05 2015-12-10 I Shou University Optical fiber communication method and system

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62109011A (ja) * 1985-11-06 1987-05-20 エイ・ティ・アンド・ティ・コーポレーション 単モ−ド光フアイバ用カツプリング装置および同装置を有する通信装置
JPH04288510A (ja) * 1989-12-26 1992-10-13 United Technol Corp <Utc> 光を反射させる埋め込み型ブラッグ回折格子を有する光導波路構成と埋め込み型ブラッグ回折格子を有する光導波路及びその製法
JPH11284263A (ja) * 1998-01-30 1999-10-15 Hitachi Cable Ltd 超広帯域波長分散補償デバイス，およびそれを用いた光通信システム
JP2005241712A (ja) * 2004-02-24 2005-09-08 Fujitsu Ltd 光合波方法および光合波器、並びに、それを用いた光増幅器
US20060013527A1 (en) * 2004-07-15 2006-01-19 Yannick Morel Optical distribution system for sensors
US7289700B1 (en) * 2006-05-19 2007-10-30 United States Of America As Represented By The Secretary Of The Navy Blazed grating optical fiber polarizing coupler
JP2012098513A (ja) * 2010-11-02 2012-05-24 Kyoto Institute Of Technology 波長選択フィルタ及びそれを備えたフィルタ装置及びレーザ装置

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111929778A (zh) * 2020-07-20 2020-11-13 西安立芯光电科技有限公司 一种半导体激光合束技术

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