WO2018155535A1 - Dispositif de déviation de lumière - Google Patents

Dispositif de déviation de lumière Download PDF

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Publication number
WO2018155535A1
WO2018155535A1 PCT/JP2018/006385 JP2018006385W WO2018155535A1 WO 2018155535 A1 WO2018155535 A1 WO 2018155535A1 JP 2018006385 W JP2018006385 W JP 2018006385W WO 2018155535 A1 WO2018155535 A1 WO 2018155535A1
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Prior art keywords
periodic
waveguide core
waveguide
length direction
refractive index
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PCT/JP2018/006385
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English (en)
Japanese (ja)
Inventor
馬場　俊彦
萌江 竹内
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国立大学法人横浜国立大学
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Priority to JP2019501398A priority Critical patent/JP6883828B2/ja
Publication of WO2018155535A1 publication Critical patent/WO2018155535A1/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
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B6/122—Basic optical elements, e.g. light-guiding paths
    • 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
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B6/122—Basic optical elements, e.g. light-guiding paths
    • G02B6/124—Geodesic lenses or integrated gratings

Definitions

  • the present invention relates to an optical deflection device that controls the traveling direction of light.
  • Laser radar or lidar equipment LiDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging)
  • LiDAR Light Detection and Ranging, Laser Imaging Detection and Ranging
  • Laser radar or lidar equipment that uses laser measurement to acquire the distance to surrounding objects as a two-dimensional image It is used for making maps, and its basic technology can be applied to laser printers and laser displays.
  • a light beam is applied to an object, reflected light that is reflected back from the object is detected, distance information is obtained from the time difference or frequency difference, and the light beam is scanned two-dimensionally. To obtain wide-angle three-dimensional information.
  • An optical deflection device is essential for optical beam scanning.
  • mechanical mechanisms such as rotating the entire device, mechanical mirrors such as polygonal mirrors (polygon mirrors) and galvano mirrors, and small integrated mirrors using micromachine technology (MEMS technology) have been used.
  • MEMS technology micromachine technology
  • phased array type or a diffraction grating type that realizes optical deflection by changing the wavelength of light or the refractive index of the device has been proposed.
  • the phased array type optical deflection device has a problem that it is very difficult to adjust the phase of a large number of light emitters arranged in an array, and a high-quality sharp light beam cannot be formed.
  • the diffraction grating type optical deflection device can easily form a sharp beam, there is a problem that the optical deflection angle is small.
  • the inventors of the present invention have proposed a technique for increasing the light deflection angle by coupling the slow light waveguide to a diffraction mechanism such as a diffraction grating (Patent Document 1).
  • Slow light is generated in a photonic nanostructure such as a photonic crystal waveguide and has a low group velocity.
  • Slow light has a characteristic that the propagation constant is greatly changed by a slight change in wavelength or refractive index of the waveguide.
  • the slow light waveguide is coupled to the diffractive mechanism to form a leaky waveguide, and emits light into free space. At this time, a large change in the propagation constant is reflected in the deflection angle of the emitted light, and as a result, a large deflection angle is realized.
  • the slow light propagating light is non-radiating in a periodic structure in which a circular hole of one kind of diameter is repeated along the waveguide in the plane of the photonic crystal.
  • the slow light propagating light is converted into radiation conditions and emitted into space.
  • a photonic crystal waveguide having a periodic structure formed by repeating circular holes of one type of diameter emits propagating light by a diffraction mechanism such as a diffraction grating.
  • a diffraction mechanism such as a diffraction grating.
  • the double periodic structure in which two types of holes having different diameters are repeated in the plane of the photonic crystal is composed of one component in which a diffraction mechanism is incorporated in the photonic crystal waveguide.
  • FIG. 7A to 7D show an outline of a device structure in which a diffraction mechanism is introduced into a photonic crystal waveguide that propagates light (slow light) having a low group velocity and a radiation beam emitted therefrom.
  • the optical deflection device 101A includes a photonic crystal waveguide 102 having a double periodic structure in which circular holes 111a and 111b having two different diameters are repeated.
  • a photonic crystal waveguide 102 in which a low refractive index portion 111 is arranged on a high refractive index member 101 is provided on a clad 106 made of a low refractive index material such as SiO 2 .
  • the lattice arrangement 112 of the low refractive index portion 111 is, for example, a double periodic structure of a periodic structure in which large-diameter circular holes are repeated and a periodic structure in which small-diameter circular holes are repeated.
  • the large and small diameters of the circular holes forming the double periodic structure indicate a large or small relationship with respect to the diameter of the reference circular hole or in comparison of the diameters of the reference circular holes.
  • the diameter 2r1 of the large-diameter circular hole 111a is 2 (r + ⁇ r)
  • the diameter 2r2 of the small-diameter circular hole 111b is 2 (r ⁇ r).
  • a portion where the circular holes 111 are not provided constitutes a waveguide core 105 that propagates incident light.
  • (Second device structure) 7C and 7D show the device structure of the second optical deflection device.
  • a surface diffraction grating 103 is disposed on a photonic crystal waveguide 102 having a periodic structure formed by repeating circular holes 111c having one type of diameter.
  • circular holes 111c at low refractive index portions are periodically arranged in the high refractive index member 101, and the photonic crystal waveguide 102 is formed.
  • a surface diffraction grating 103 is disposed on the photonic crystal waveguide 102 and constitutes a diffraction mechanism for emitting propagating light.
  • propagating light propagating through a waveguide core is emitted little by little along the waveguide by a diffraction mechanism, and a radiated light beam is formed.
  • the emitted light beam is deflected by changing the refractive index and incident wavelength of the waveguide of the optical deflection device.
  • the emitted light beam is a sharp beam having a uniform beam intensity distribution in the direction along the waveguide (here, the longitudinal direction).
  • the slow light is confined in the narrow waveguide core 105 and propagates in the direction orthogonal to the waveguide (here, the lateral direction). Since the light is radiated from there, the light beam generally spreads. In addition, since the light emitted from the periodic waveguide mode distribution interferes with each other due to the periodicity of the photonic crystal, a complicated lateral distribution may be formed.
  • FIG. 8A and 8B are diagrams for explaining the beam intensity distribution of the emitted light beam
  • FIG. 8A shows the beam intensity distribution in the vertical direction
  • FIG. 8B shows the beam intensity distribution in the horizontal direction.
  • the radiated light beam gradually leaks along the waveguide, so that the beam intensity distribution in the vertical direction becomes a sharp beam.
  • the lateral beam intensity distribution has a wide angular distribution.
  • the emitted light beam from the optical deflection device is required to be uniform in beam intensity in the vertical direction, to suppress the spread of the beam intensity distribution in the horizontal direction, and to be unimodal. .
  • a configuration is often used in which a collimating lens is installed above the light deflection device and the radiated light beam from the waveguide is converted into a parallel beam.
  • the conversion to a parallel beam by the collimating lens does not suppress the occurrence of the lateral distribution of the light beam itself, although it suppresses the lateral divergence angle, and the beam has a plurality of lateral peaks.
  • the intensity distribution is maintained as it is even after conversion to a parallel beam.
  • the present invention is directed to an optical deflection device that suppresses the spread of the beam intensity distribution of the radiated light beam in the lateral direction and makes the beam intensity distribution of the radiated light beam unimodal.
  • the optical deflection device of the present invention is a diffraction mechanism that diffracts the light beam emitted from the waveguide core in the outward direction, and when the length direction of the waveguide core is the vertical direction, the waveguide mode changes in the horizontal direction in order.
  • the lateral spread of the beam intensity distribution of the radiated light beam is suppressed.
  • the radiation from the electromagnetic field having the same sign of the transverse distribution of the waveguide mode interference at a distant place is suppressed and a unimodal beam is formed.
  • the optical deflection device of the present invention deflects the propagation light of a photonic crystal waveguide in which low refractive index portions are periodically arranged in a plane of a high refractive index member and a waveguide core of the photonic crystal waveguide.
  • a diffraction mechanism that emits a radiation light beam to the outside, and the diffraction mechanism includes a plurality of periodic portions arranged along the length direction of the waveguide core, and each periodic portion extends in the length direction of the waveguide core. On the other hand, it is arranged at an acute angle or an obtuse angle.
  • the optical deflecting device of the present invention has a double period in which a photonic crystal waveguide repeats two types of low-refractive-index portions in a lattice arrangement formed by arranging low-refractive-index portions on a high-refractive-index member.
  • a first form having a structure and a second form having a periodic structure in which the photonic crystal waveguide repeats one kind of low refractive index portion having the same size are included.
  • the photonic crystal waveguide and the diffraction mechanism include two types of low refractive index portions having different sizes along the length direction of the waveguide core in the plane of the high refractive index member.
  • a lattice arrangement of a double periodic structure arranged periodically is provided.
  • the diffraction mechanism includes two types of periodic parts in which a low-refractive index part of the same size is periodically arranged in a lattice arrangement of a double periodic structure.
  • the two types of periodic portions are alternately arranged along the length direction of the waveguide core, and are arranged at an acute angle or an obtuse angle with respect to the length direction of the waveguide core.
  • the periodic portions are alternately arranged along the length direction of the waveguide core according to a plurality of arrangement forms, and can be arranged at an acute angle or an obtuse angle with respect to the length direction of the waveguide core.
  • each periodic part of the diffraction mechanism is arranged in a V shape or an inverted V shape with respect to the length direction of the waveguide core.
  • the waveguide mode oozes out from the waveguide core in the lateral direction, thereby gradually reducing the confinement of light in the waveguide core, and the radiation angle.
  • the distribution is narrowed to about ⁇ 25 °.
  • this V-shaped periodic part pattern promotes radiation from an electromagnetic field having the same sign in the transverse distribution of the waveguide mode, thereby suppressing interference at a distance and forming a unimodal beam. Play.
  • each periodic part of the diffraction mechanism is an arrangement called a grating shift in which a linear arrangement of a part of the low refractive index part of the grating arrangement is displaced with respect to the length direction of the waveguide core.
  • a grating shift in which a linear arrangement of a part of the low refractive index part of the grating arrangement is displaced with respect to the length direction of the waveguide core.
  • two linear arrangements at positions symmetrical to the waveguide core are different from the other linear arrangements.
  • the waveguide cores are arranged so as to be displaced in the length direction.
  • the V-shaped arrangement with lattice shift according to the second arrangement form has an effect of uniforming the deflection angle characteristics of the photonic crystal waveguide that is not lattice-shifted.
  • each periodic part of the diffraction mechanism is a lattice arrangement
  • the grating arrangement in the vicinity of the waveguide core has a double periodic structure
  • the first arrangement form for two kinds of periodic parts of the double periodic structure.
  • the other lattice arrangement is a periodic structure.
  • the lattice arrangement of the photonic crystal waveguide in the length direction of the waveguide core Among the two types of lattice arrangements arranged along the low-refractive-index regions arranged along the periodic array, the multiple rows of lattice arrangements near the waveguide core have a double periodic structure, and the remaining lattice arrangements are the same.
  • a periodic structure in which low-refractive-index portions having a size are periodically arranged is used.
  • a double periodic structure can be provided only in the vicinity of the waveguide core where the waveguide modes are mainly concentrated. The effect is made simpler and unimodal.
  • each periodic part of the diffraction mechanism is arranged in a V shape or an inverted V shape similarly to the first arrangement form, and for two types of periodic parts of the double periodic structure of the lattice arrangement,
  • the sizes of the low refractive index portions are arranged in gradation, and the low refractive index portions are arranged so that the size of the low refractive index portions increases or decreases in order along the arrangement direction of the low refractive index portions.
  • the 4th arrangement form is the form which combined V shape or reverse V shape and gradation arrangement.
  • the combination of the V shape and the gradation arrangement has the effect of making the lateral distribution of the emitted light beam smoother by making the double periodic structure gradually uniform as the distance from the waveguide core increases. Play.
  • the form in which the inverted V shape and the gradation arrangement are combined has an effect of effectively widening the width in which the waveguide mode is radiated and narrowing the lateral distribution.
  • each periodic part of the diffraction mechanism is an arrangement form in which two kinds of periodic parts of the double periodic structure intersect with the waveguide core at an acute angle or an obtuse angle.
  • the periodic part on the side is arranged at an acute angle with respect to the length direction of the waveguide core, and the periodic part on the other side is arranged at an obtuse angle with respect to the length direction of the waveguide core.
  • the lattice arrangement of the double periodic structure has a circular pattern of the photonic crystal having a large diameter hole and a small diameter circular hole. It is composed by repeating.
  • this double periodic structure composed of large and small circular holes in addition to fewer processing steps, changing the amount of change in the size of the circular hole in the plane can change the amount of radiation without changing the radiation angle. Therefore, the longitudinal distribution of the radiated light beam is gradually changed to a Gaussian distribution in the waveguide propagation direction, so that a high-quality beam with little side loop in the longitudinal direction can be formed.
  • a photonic crystal waveguide having a periodic structure in which low-refractive index portions of one kind are repeated and a diffraction mechanism are arranged on the photonic crystal waveguide.
  • the photonic crystal waveguide includes a grating structure having a periodic structure in which low refractive index portions having the same size are periodically arranged along the length direction of the waveguide core in the plane of the high refractive index member.
  • the diffraction mechanism is a surface diffraction grating arranged on a grating array of photonic crystal waveguides.
  • the periodic parts included in the surface diffraction grating are concavo-convex arrays, and each periodic part is arranged at an acute angle or an obtuse angle with respect to the waveguide core.
  • the periodic part can be arranged at an acute angle or an obtuse angle with respect to the length direction of the waveguide core depending on a plurality of forms.
  • each periodic part of the surface diffraction grating is arranged in a V shape or an inverted V shape with respect to the length direction of the waveguide core. Also in the first arrangement form of the periodic parts of the surface diffraction grating, the same effect as that of the form in which the V-shaped or inverted V-shaped periodic parts are arranged in the double periodic structure.
  • each periodic part of the surface diffraction grating is an arrangement form in which the periodic part of the periodic structure intersects the waveguide core at an acute angle or an obtuse angle, and the periodic part on one side with respect to the waveguide core. Are arranged at an acute angle with respect to the length direction of the waveguide core, and the periodic part on the other side is arranged at an obtuse angle with respect to the length direction of the waveguide core.
  • the optical deflection device of the present invention suppresses the lateral spread of the beam intensity distribution of the radiated light beam in the lateral distribution of the radiated light beam, and the beam intensity distribution of the radiated light beam is unimodal. It can be.
  • each periodic part which constitutes a diffraction mechanism. It is the 3rd arrangement form of each periodic part which constitutes a diffraction mechanism. It is the 4th arrangement form of each periodic part which constitutes a diffraction mechanism. It is the 4th arrangement form of each periodic part which constitutes a diffraction mechanism. It is a figure for demonstrating the structural example of the double periodic structure of the 1st form of this invention, and is the 5th arrangement
  • positioning form which comprises a diffraction mechanism with a surface diffraction grating. It is a figure for demonstrating the device structure which introduce
  • FIG. 1 a schematic configuration example of the optical deflection device of the present invention will be described with reference to FIG. 1, and a first example of the optical deflection device of the present invention will be described with reference to FIGS. 2A to 2D, 3A to 3F, 4A, and 4B.
  • the second embodiment of the present invention will be described with reference to FIGS. 5A, 5B, and 6A to 6E.
  • FIG. 1 is a diagram for explaining an outline of an optical deflection device of the present invention.
  • the optical deflection device 1 includes a photonic crystal waveguide 2 in which low refractive index regions 11 are periodically arranged in a plane of a high refractive index member 10, and light propagating through a waveguide core 5 of the photonic crystal waveguide 2. And a diffraction mechanism 3 that emits a radiation beam to the outside.
  • the photonic crystal waveguide 2 and the diffraction mechanism 3 are provided on a clad 6 made of a semiconductor material such as Si.
  • Incident light incident on the waveguide core 5 is radiated from the waveguide core 5 to the outside by the diffraction mechanism 3 while propagating in the length direction in the waveguide core 5.
  • the arrows in FIG. 1 schematically indicate incident light and emitted light beams.
  • the photonic crystal waveguide 2 is formed by a lattice arrangement in which low refractive index portions 11 are periodically arranged on a high refractive index member 10 made of a semiconductor such as Si.
  • the low refractive index region 11 can be, for example, a circular hole provided in the high refractive index member 10.
  • a waveguide core 5 for propagating light is formed by providing a portion where the low refractive index portion 11 is not provided in a part of the lattice arrangement.
  • the waveguide core 5 is formed by providing a part where the circular hole is not disposed in a part of the lattice arrangement.
  • the diffraction mechanism 3 is a mechanism that deflects the propagation light of the waveguide core 5 and emits a radiated light beam to the outside, and includes a plurality of periodic portions 4 arranged along the length direction of the waveguide core 5, Each periodic part 4 is arranged at an acute angle or an obtuse angle with respect to the length direction of the waveguide core 5. As one form of disposing the periodic part 4, it is disposed in a V shape or an inverted V shape with respect to the length direction of the waveguide core 5.
  • the periodic part 4 included in the diffraction mechanism 3 is arranged at an acute angle or an obtuse angle with respect to the length direction of the waveguide core 5 when the longitudinal direction of the waveguide core 5 is the longitudinal direction.
  • the degree of lateral action on the wave mode is reduced, the light confinement of the waveguide core 5 is weakened and the waveguide mode is oozed out, thereby narrowing the radiation angle distribution in the transverse direction of the radiation light beam.
  • the effect of narrowing the radiation angle distribution can be about ⁇ 25 °, for example.
  • the V-shaped periodic portion has the same sign in the lateral distribution of the waveguide mode.
  • the radiation from the electromagnetic field is promoted, the interference of the radiation light beam is suppressed at a distance far from the optical deflection device, and the formation of a plurality of peaks is suppressed to form a unimodal beam.
  • the diffraction mechanism 3 of the optical deflection device 1 of the present invention is a first form formed together with the lattice arrangement of the photonic crystal waveguide 2 or a photonic crystal waveguide as a separate component from the photonic crystal waveguide 2 It can be set as the 2nd form which overlaps and comprises.
  • the photonic crystal waveguide 2 has a double periodic structure in which two types of low refractive index portions having different sizes are periodically arranged, and the diffraction mechanism 3 has the double structure.
  • the periodic part of each periodic structure constituting the periodic structure is arranged at an acute angle or an obtuse angle with respect to the length direction of the waveguide core 5.
  • the photonic crystal waveguide 2 has a periodic structure in which one kind of low refractive index portion having the same size is periodically arranged, and the diffraction mechanism 3 is a surface diffraction grating.
  • the photonic crystal waveguides 2 are arranged on the lattice arrangement of the photonic crystal waveguides 2.
  • the periodic part 4 of the diffraction mechanism 3 is schematically shown to represent both the first form and the second form.
  • FIG. 2 is a diagram for explaining the first schematic configuration and the lateral spread of the emitted light beam
  • FIGS. 3A to 3F, 4A, and 4B show the configuration of the double periodic structure of the first embodiment. It is a figure for demonstrating an example.
  • two types of low refractive index portions 11a and 11b having different sizes are periodically arranged along the length direction of the waveguide core 5 in the plane of the high refractive index member 10.
  • a lattice array 12 having a double periodic structure is formed.
  • the photonic crystal waveguide 2 and the diffraction mechanism 3 are formed on the same grating array 12.
  • the low refractive index portions 11a and 11b can be formed by circular holes formed in the high refractive index member 10 and having different diameters.
  • a circular hole as a low-refractive index part in a lattice arrangement with a double periodic structure
  • the radiation angle The amount of radiation can be changed without changing.
  • the longitudinal distribution of the radiated light beam is gradually changed to a Gaussian distribution in the propagation direction of the waveguide, and a high-quality beam with little side loop in the longitudinal direction can be formed.
  • the conventionally proposed double periodic structure of the lattice array 12 is such that the circular holes 111a and 111b of the triangular lattice pattern are periodically formed in the high refractive index material 110 such as Si as shown in FIG. 7B.
  • An optical waveguide core 105 is formed by providing a region where the circular holes (111a, 111b) are not formed in the central portion.
  • circular holes (111a, 111b) having large and small diameters are arranged along the length direction of the waveguide core 5, which is the traveling direction of light propagating in the waveguide core 5.
  • a double periodic structure is formed, and the light propagating through the waveguide core 5 is emitted out of the plane by the double periodic structure.
  • the angular distribution in the lateral direction of the radiation light beam formed by this double periodic structure has a wide angular distribution range of about ⁇ 80 ° as shown in FIG. 2D, and the light intensity peak is split into three. .
  • Such a wide angular distribution is attributed to the fact that the propagation light of the waveguide core 5 is radiated out of the plane from the state where it is strongly confined, and the three splits of the light intensity peak are in the transverse direction of the waveguide mode.
  • the distribution oscillates in the positive and negative directions, and it is assumed that radiation from electromagnetic fields having different signs interfere with each other to form a belly and a node.
  • the double periodic structure 3A provided in the optical deflection device 1 according to the first embodiment of the present invention has a length of the waveguide core 5 in the plane of the high refractive index member 10.
  • FIG. 2B shows an example in which two types of low refractive index portions of the lattice arrangement are configured by a large diameter circular hole 11a and a small diameter circular hole 11b.
  • the arrangement in which the large-diameter circular holes 11a extend in the horizontal oblique direction from the waveguide core 5 constitutes the periodic part 4Aa
  • the arrangement in which the small-diameter circular holes 11b extend in the horizontal oblique direction from the waveguide core 5 is the periodic part 4Ab.
  • the two types of periodic portions 4Aa and 4Ab are alternately arranged along the length direction of the waveguide core 5 (the traveling direction of the light propagating through the waveguide core 5). It is arranged at an acute angle or an obtuse angle with respect to the length direction of the waveguide core 5.
  • the arrangement of the periodic parts 4Aa and 4Ab is V-shaped or inverted V-shaped. .
  • the lattice arrangement of the first form constitutes the photonic crystal waveguide 2 and the diffraction mechanism 3.
  • FIG. 2C shows the angular distribution in the lateral direction of the emitted light beam by the lattice arrangement having a V-shaped periodic portion in the double periodic structure of the present invention.
  • the V-shaped periodic part causes the waveguide mode to ooze out from the waveguide core in the lateral direction to moderately weaken light confinement, the radiation angle distribution is narrowed to about ⁇ 25 °. Further, the V-shaped periodic part promotes radiation from the electromagnetic field having the same sign in the transverse distribution of the waveguide mode, so that interference at a distant place is suppressed and a unimodal beam is formed.
  • the wavelength is 1.55 ⁇ m
  • the lattice constant of the photonic crystal is 400 nm
  • the diameter 2r1 of the large-diameter hole 11a is 215 nm
  • the diameter of the small-diameter hole 11b is 2r2 is 295 nm
  • the refractive index of the refractive index member 10 is 3.5
  • the thickness is 210 nm
  • the refractive index of the upper cladding and the lower cladding 6 is 1.45.
  • the periodic portions 4Aa and 4Ab are alternately arranged along the length direction of the waveguide core according to a plurality of arrangement forms, and arranged at an acute angle or an obtuse angle with respect to the length direction of the waveguide core. Can do.
  • the arrangement of the periodic parts will be described with reference to FIGS. 3A to 3F, FIG. 4A, and FIG. 4B.
  • each periodic portion 4A (4Aa, 4Ab) is arranged in a V shape or an inverted V shape with respect to the length direction of the waveguide core 5.
  • 3A and 3B show a first arrangement form of each periodic portion constituting the diffraction mechanism, FIG. 3A shows a V-shaped arrangement, and FIG. 3B shows an inverted V-shaped arrangement.
  • the waveguide mode oozes out from the waveguide core 5 in the lateral direction, thereby gradually reducing light confinement in the waveguide core 5.
  • the radiation angle distribution is narrowed to about ⁇ 25 °.
  • this V-shaped periodic part pattern promotes radiation from an electromagnetic field having the same sign in the transverse distribution of the waveguide mode, thereby suppressing interference at a distance and forming a unimodal beam. Play.
  • FIG. 3C shows a second arrangement form of each periodic part constituting the diffraction mechanism.
  • the linear array 13 of the low refractive index parts 11 a and 11 b of the periodic parts 4 Aa and 4 Ab in the grating array 12 is arranged in the length direction of the waveguide core 5.
  • the arrangement is shifted from the arrangement, which is an arrangement form called a lattice shift.
  • two linear arrays 13A and 13B that are symmetrical with respect to the waveguide core 5 are:
  • the waveguide core 5 is arranged so as to be displaced in the length direction with respect to the other linear arrangement. This second arrangement form uniformizes the deflection angle characteristics of the photonic crystal waveguide 2 that is not misaligned.
  • FIG. 3D shows a third arrangement form of each periodic part constituting the diffraction mechanism.
  • the third arrangement form of the periodic parts constituting the diffraction mechanism 3 is that in the grating array 12, the grating arrays 14A and 14B in the vicinity of the waveguide core 5 have a double periodic structure, and two kinds of periods of the double periodic structure are used.
  • the parts 4Aa and 4Ab are arranged in a V shape or an inverted V shape similarly to the first arrangement form, and the other lattice arrangements 15A and 15B have the same periodic structure.
  • the waveguide is one of the lattice arrangements 12 in which two types of low refractive index portions 11a and 11b having different sizes arranged along the length direction of the waveguide core are periodically arranged.
  • a plurality of lattice arrays 14A and 14B in the vicinity of the core have a double periodic structure, and the remaining lattice arrays 15A and 15B have a periodic structure in which low refractive index portions 11 of the same size are periodically arrayed.
  • (d) Fourth arrangement form: 3E and 3F show a fourth arrangement form of each periodic part constituting the diffraction mechanism.
  • the fourth arrangement form of each periodic part of the diffraction mechanism is arranged in a V shape or an inverted V shape similarly to the first arrangement form, and two kinds of periods of the double periodic structure of the grating array 12 are arranged.
  • the size of the low refractive index portion is arranged in gradation.
  • the low refractive index portions 11b are arranged so that the size of the low refractive index portions 11b sequentially increases along the arrangement direction of the low refractive index portions.
  • the low refractive index portions 11a are arranged so that the size of the low refractive index portions 11a sequentially increases along the arrangement direction of the low refractive index portions.
  • FIG. 4th arrangement form is the form which combined V shape or reverse V shape and gradation arrangement.
  • FIG. 3E shows a combination of a V shape and a gradation array. In this arrangement, the structure in which the double periodic structure is gradually uniformed as the distance from the waveguide core is increased, so that the lateral distribution of the emitted light beam is more smoothly smoothed.
  • FIG. 3F shows a combination of an inverted V shape and a gradation array. In this arrangement form, the width in which the guided mode is radiated is effectively widened, and the lateral distribution is further narrowed.
  • the fifth arrangement form of each periodic part of the diffraction mechanism is an arrangement form in which two kinds of periodic parts of the double periodic structure intersect the waveguide core at an acute angle or an obtuse angle.
  • 4A with the waveguide core 5 as the center, the periodic part 16A on one side is arranged at an acute angle with respect to the length direction of the waveguide core 5, and the periodic part 16B on the other side is disposed on the waveguide core 5. It is arranged at an obtuse angle with respect to the length direction.
  • the arrangement shown in FIG. 4B shows a configuration in which the arrangement shown in FIG. 4A is symmetric with respect to the waveguide core 5.
  • FIGS. 5A, 5B, and 6A to 6E A second embodiment of the optical deflection device of the present invention will be described with reference to FIGS. 5A, 5B, and 6A to 6E.
  • 5A and 5B are diagrams for explaining the second schematic configuration
  • FIGS. 6A to 6E are diagrams for explaining a configuration example of the surface diffraction grating of the second embodiment.
  • the second embodiment of the optical deflection device is a photonic crystal waveguide 2 having a grating structure 12 having a periodic structure in which low-refractive index portions 11 having one size are repeated, and the photonic crystal waveguide as a diffraction mechanism 3. 2 is provided with a surface diffraction grating 3B.
  • the photonic crystal waveguide 2 includes a grating structure 12 having a periodic structure in which low refractive index portions 11 having the same size are periodically arranged along the length direction of the waveguide core 5 in the plane of the high refractive index member 10. .
  • the diffraction mechanism 3 is configured by disposing a surface diffraction grating 3 ⁇ / b> B on the grating array 12 of the photonic crystal waveguide 2.
  • the periodic part 4B (convex part 4Ba, concave part 4Bb) provided in the surface diffraction grating 3B is an uneven arrangement, and each periodic part 4B (4Ba, 4Bb) is arranged at an acute angle or an obtuse angle with respect to the waveguide core 5.
  • the convex portion 4Ba of the surface diffraction grating 3B and the 4Bb concave portion of the surface diffraction grating 3B are used as the periodic portion 4B.
  • the periodic portion of the convex portion 4Ba of the surface diffraction grating 3B is a dark ground pattern.
  • the periodic part of the concave portion 4Bb of the surface diffraction grating 3B is indicated by a thin ground pattern.
  • the form in which the periodic parts (projections 4Ba, recesses 4Bb) of the surface diffraction grating 3B are arranged at an acute angle or an obtuse angle with respect to the length direction of the waveguide core 5 can be a plurality of forms.
  • the first arrangement form of the periodic parts (convex part 4Ba, concave part 4Bb) of the surface diffraction grating 3B is a V-shaped or convex part 4Ba and concave part 4Bb of each periodic part 4B with respect to the length direction of the waveguide core 5. Arranged in an inverted V-shape. Even in the first arrangement form of the periodic parts by the surface diffraction grating, the same effect as that of the form in which the periodic parts are arranged in a V-shaped or inverted V-shaped shape in the double periodic structure is obtained.
  • FIG. 6A, FIG. 6B, and FIG. 6C show a first arrangement form in which a diffraction mechanism is constituted by a surface diffraction grating.
  • FIG. 6A shows a V-shaped configuration in which the angle of the convex portions 4Ba and the concave portions 4Bb, which are each periodic part of the surface diffraction grating 3B, is 60 ° in a triangular arrangement of circular holes.
  • the holes are arranged in a triangular pattern
  • an inverted V-shaped configuration is shown in which the angles of the convex portions 4Ba and the concave portions 4Bb that are each periodic portion of the surface diffraction grating 3B are 120 °.
  • FIG. 6C shows a V-shaped configuration in which the angle of the convex portions 4Ba and the concave portions 4Bb, which are each periodic portion of the surface diffraction grating 3B, is 30 ° in a lattice arrangement in which circular holes are arranged in a triangle.
  • each periodic part of the surface diffraction grating is an arrangement form in which the periodic part of the periodic structure intersects the waveguide core at an acute angle or an obtuse angle, and the periodic part on one side with respect to the waveguide core. Are arranged at an acute angle with respect to the length direction of the waveguide core, and the periodic part on the other side is arranged at an obtuse angle with respect to the length direction of the waveguide core.
  • FIG. 6D and FIG. 6E show a second arrangement form in which the diffraction mechanism is constituted by the surface diffraction grating.
  • FIG. 6D shows a convex arrangement on one side with respect to the waveguide core 5 by inclining the convex portions 4Ba and the concave portions 4Bb, which are each periodic portion of the surface diffraction grating 3B, in one direction in a triangular arrangement of circular holes.
  • the portion 4Ba and the concave portion 4Bb are arranged at 60 ° with respect to the length direction of the waveguide core 5, and the convex portion 4Ba and the concave portion 4Bb on the other side are arranged at 120 ° with respect to the length direction of the waveguide core 5. .
  • a normal surface diffraction grating has a simple linear diffraction grating having a period twice that of a photonic crystal.
  • the configuration using this diffraction grating has a wide lateral angle distribution as in the conventional double periodic structure shown in FIG. 2D.
  • the light intensity peak is a radiation light beam divided into a plurality.
  • the diffraction grating of the surface diffraction grating is arranged at an acute angle or an obtuse angle with respect to the length direction of the waveguide core, similarly to the first embodiment of the optical deflection device having the double periodic structure of the present invention. As a result, a unidirectional radiation light beam with a narrow divergence angle can be obtained.
  • the optical deflection device and the lidar apparatus (laser radar) of the present invention can be mounted on automobiles, drones, robots, etc., and can be mounted on a personal computer or a smartphone to easily capture the surrounding environment, a monitoring system, optical exchange, It can be applied to a space matrix optical switch for a data center.
  • Si is used as the high refractive index member constituting the photonic crystal waveguide of the optical deflection device, and light in the near infrared wavelength range is used.
  • a visible light material as a refractive index member
  • a projector a laser display, a retina display, a 2D / 3D printer, a POS, a card reading, and the like is expected.

Abstract

L'invention concerne un dispositif de déviation de lumière comprenant un mécanisme de diffraction pour diffracter des faisceaux de lumière émis par un cœur de guide d'ondes vers une direction externe, le mécanisme étant conçu pour changer séquentiellement des modes de guide d'ondes dans une direction transverse, la direction du cœur de guide d'ondes étant une direction longitudinale. Les degrés de confinement de la lumière dans la direction transverse sont séquentiellement diminués pour modifier l'état de fuite du cœur de guide d'ondes, ce qui entraîne la suppression d'un étalement transverse de la distribution d'intensité de faisceaux de lumière émis, et favorise le rayonnement provenant de champs électromagnétiques présentant le même signe dans la distribution transverse de modes de guide d'ondes, les interférences à un endroit distant sont donc supprimées, afin de former un faisceau unimodal. En raison de la caractéristique, dans la distribution transverse de faisceaux de lumière émis, l'étalement transverse de la distribution d'intensité de faisceaux de lumière émis est supprimé de sorte que la distribution d'intensité de faisceaux de lumière émis présente une unimodalité.
PCT/JP2018/006385 2017-02-24 2018-02-22 Dispositif de déviation de lumière WO2018155535A1 (fr)

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WO2023026712A1 (fr) * 2021-08-24 2023-03-02 国立大学法人京都大学 Coupleur de réseau

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WO2023026712A1 (fr) * 2021-08-24 2023-03-02 国立大学法人京都大学 Coupleur de réseau

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