WO2023218703A1 - 光デバイスおよび光検出システム - Google Patents

光デバイスおよび光検出システム Download PDF

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Publication number
WO2023218703A1
WO2023218703A1 PCT/JP2023/003320 JP2023003320W WO2023218703A1 WO 2023218703 A1 WO2023218703 A1 WO 2023218703A1 JP 2023003320 W JP2023003320 W JP 2023003320W WO 2023218703 A1 WO2023218703 A1 WO 2023218703A1
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Prior art keywords
optical waveguide
optical
light
optical device
waveguide
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PCT/JP2023/003320
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English (en)
French (fr)
Japanese (ja)
Inventor
幸生 野村
和樹 中村
安寿 稲田
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Panasonic Intellectual Property Management Co Ltd
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Panasonic Intellectual Property Management Co Ltd
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Priority to JP2024520255A priority Critical patent/JPWO2023218703A1/ja
Publication of WO2023218703A1 publication Critical patent/WO2023218703A1/ja
Priority to US18/914,286 priority patent/US20250036001A1/en
Anticipated expiration legal-status Critical
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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/19—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on variable-reflection or variable-refraction elements not provided for in groups G02F1/015 - G02F1/169
    • G02F1/195—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on variable-reflection or variable-refraction elements not provided for in groups G02F1/015 - G02F1/169 by using frustrated reflection
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/1326—Liquid crystal optical waveguides or liquid crystal cells specially adapted for gating or modulating between optical waveguides
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133524—Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133553—Reflecting elements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1341—Filling or closing of cells
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/29—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the position or the direction of light beams, i.e. deflection
    • G02F1/295—Analog deflection from or in an optical waveguide structure]

Definitions

  • the present disclosure relates to optical devices and optical detection systems.
  • Patent Document 1 discloses a configuration in which scanning with light can be performed using a drive device that rotates a mirror.
  • Patent Document 2 discloses an optical phased array having a plurality of nanophotonic antenna elements arranged two-dimensionally. Each antenna element is optically coupled to a variable optical delay line (ie, a phase shifter). In this optical phased array, a coherent light beam is guided to each antenna element by a waveguide, and the phase of the light beam is shifted by a phase shifter. This allows the amplitude distribution of the far-field radiation pattern to be changed.
  • a variable optical delay line ie, a phase shifter
  • Patent Document 3 discloses a waveguide including an optical waveguide layer through which light is guided, a first distributed Bragg reflector formed on the upper and lower surfaces of the optical waveguide layer, and a waveguide for allowing light to enter the waveguide.
  • An optical deflection element is disclosed that includes a light input aperture and a light output aperture formed on the surface of the waveguide for outputting light that enters from the light input aperture and is guided within the waveguide.
  • One aspect of the present disclosure provides an optical device that can suppress a decrease in the intensity of emitted light or received light.
  • An optical device includes a first structure having a first surface, a second structure having a second surface opposite to the first surface, and the first surface of the first structure. and the second surface of the second structure, the distance between the first structure and the second structure being fixed; a sealing member surrounding the one or more optical waveguide regions, the sealing member having an opening for injecting the liquid crystal material, the width of the opening in the first direction being equal to or larger than the one or more optical waveguide regions; is larger than the width of the optical waveguide region in the first direction.
  • the general or specific aspects of the present disclosure may be implemented in a system, apparatus, method, integrated circuit, computer program or recording medium such as a computer readable recording disk, and the system, apparatus, method, integrated circuit, It may be realized by any combination of a computer program and a recording medium.
  • the computer-readable recording medium may include, for example, a non-volatile recording medium such as a CD-ROM (Compact Disc-Read Only Memory).
  • a device may be composed of one or more devices. When the device is composed of two or more devices, the two or more devices may be placed within one device, or may be separately placed within two or more separate devices.
  • “device” may refer not only to a device, but also to a system of devices.
  • an optical device that can suppress a decrease in the intensity of emitted light or received light.
  • FIG. 1 is a perspective view schematically showing the configuration of an optical scanning device.
  • FIG. 2 is a diagram schematically showing an example of the cross-sectional structure of one waveguide element and propagating light.
  • FIG. 3A is a diagram showing a cross section of a waveguide array that emits light in a direction perpendicular to the output surface of the waveguide array.
  • FIG. 3B is a diagram showing a cross section of a waveguide array that emits light in a direction different from the direction perpendicular to the output surface of the waveguide array.
  • FIG. 4 is a perspective view schematically showing a waveguide array in three-dimensional space.
  • FIG. 5 is a schematic diagram of the waveguide array and the phase shifter array viewed from the normal direction (Z direction) of the light exit surface.
  • FIG. 6A is a top view schematically showing the configuration of an optical scanning device according to a comparative example.
  • FIG. 6B is a top view schematically showing the configuration of the lower structure shown in FIG. 6A.
  • FIG. 6C is a sectional view taken along the line VIC-VIC of the optical scanning device shown in FIG. 6A.
  • FIG. 7 is a photograph showing the results of an experiment in which liquid crystal material was injected through a narrow opening in an optical scanning device according to a comparative example.
  • FIG. 8A is a top view schematically showing the configuration of an optical device according to exemplary embodiment 1 of the present disclosure.
  • FIG. 8B is a diagram schematically showing an example of a state in which the upper component is removed from FIG. 8A.
  • FIG. 8C is a diagram schematically showing another example in which the upper component is removed from FIG. 8A.
  • FIG. 8D is a diagram schematically showing still another example in which the upper component is removed from FIG. 8A.
  • FIG. 9A is a sectional view taken along the line IXA-IXA in FIG. 8A.
  • FIG. 9B is a sectional view taken along the line IXB-IXB in FIG. 8A.
  • FIG. 9C is a sectional view taken along the line IXC-IXC in FIG. 8A.
  • FIG. 10A is a cross-sectional view schematically showing the configuration of an optical device according to exemplary embodiment 2 of the present disclosure.
  • FIG. 10A is a cross-sectional view schematically showing the configuration of an optical device according to exemplary embodiment 2 of the present disclosure.
  • FIG. 10B is another cross-sectional view schematically showing the configuration of an optical device according to exemplary embodiment 2 of the present disclosure.
  • FIG. 10C is yet another cross-sectional view schematically showing the configuration of an optical device according to exemplary embodiment 2 of the present disclosure.
  • FIG. 11A is a top view schematically showing an example of an optical device according to a modification of Embodiment 2 of the present disclosure.
  • FIG. 11B is a diagram schematically showing an example of a state in which the upper component is removed from FIG. 11A.
  • FIG. 11C is a diagram schematically showing another example in which the upper component is removed from FIG. 11A.
  • FIG. 11D is a diagram schematically showing still another example in which the upper component is removed from FIG. 11A.
  • FIG. 11A is a top view schematically showing an example of an optical device according to a modification of Embodiment 2 of the present disclosure.
  • FIG. 11B is a diagram schematically showing an example of a state in which the upper component is removed from FIG
  • FIG. 12A is a cross-sectional view taken along the line XIIA-XIIA in FIG. 11A.
  • FIG. 12B is a cross-sectional view taken along the line XIIB-XIIB in FIG. 11A.
  • FIG. 12C is a cross-sectional view taken along the line XIIC-XIIC in FIG. 11A.
  • FIG. 13 is a diagram showing a configuration example of an optical scanning device in which elements such as an optical splitter, a waveguide array, a phase shifter array, and a light source are integrated on a circuit board.
  • FIG. 14 is a schematic diagram illustrating how a two-dimensional scan is performed by irradiating a light beam such as a laser to a far distance from an optical scanning device.
  • FIG. 15 is a block diagram illustrating a configuration example of a LiDAR system capable of generating distance measurement images.
  • the present inventor discovered that conventional optical scanning devices have a problem in that it is difficult to scan space with light without complicating the configuration of the device.
  • Patent Document 1 requires a drive device to rotate the mirror. Therefore, the structure of the device becomes complicated and there is a problem that it is not robust against vibrations.
  • the present inventor focused on the above-mentioned problems in the prior art and studied a configuration for solving these problems.
  • the present inventors have discovered that the above problems can be solved by using a waveguide element having a pair of mirrors facing each other and an optical waveguide layer sandwiched between the mirrors.
  • One of the pair of mirrors in the waveguide element has a higher light transmittance than the other, and emits part of the light propagating through the optical waveguide layer to the outside.
  • the direction (or output angle) of the emitted light can be changed by adjusting the refractive index or thickness of the optical waveguide layer or the wavelength of the light input to the optical waveguide layer, as described below. More specifically, by changing the refractive index, thickness, or wavelength, the component of the wave vector of the emitted light in the longitudinal direction of the optical waveguide layer can be changed. This achieves one-dimensional scanning.
  • two-dimensional scanning can also be realized. More specifically, by giving an appropriate phase difference to the light supplied to multiple waveguide elements and adjusting that phase difference, it is possible to change the direction in which the light emitted from the multiple waveguide elements strengthens each other. can. Due to the change in phase difference, the component of the wave number vector of the emitted light in the direction intersecting the longitudinal direction of the optical waveguide layer changes. Thereby, two-dimensional scanning can be realized. Note that even when two-dimensional scanning is performed, there is no need to change the refractive index, thickness, or wavelength of light of the plurality of optical waveguide layers by different amounts.
  • Two-dimensional scanning can be performed.
  • two-dimensional scanning using light can be achieved with a relatively simple configuration.
  • any one of the refractive index, thickness, and wavelength is selected from the group consisting of the refractive index of the optical waveguide layer, the thickness of the optical waveguide layer, and the wavelength input to the optical waveguide layer.
  • any one of the refractive index, thickness, and wavelength may be independently controlled. Alternatively, any two or all of these three may be controlled to change the light emission direction.
  • the wavelength of light input to the optical waveguide layer may be controlled.
  • the above basic principles can be applied not only to applications that emit light, but also to applications that receive optical signals.
  • the direction of light that can be received can be changed one-dimensionally.
  • the phase difference of light using a plurality of phase shifters connected to a plurality of waveguide elements arranged in one direction, the direction of light that can be received can be changed two-dimensionally.
  • Optical scanning devices and optical receiving devices may be used, for example, as antennas in optical detection systems such as LiDAR (Light Detection and Ranging) systems.
  • LiDAR systems Compared to radar systems that use radio waves such as millimeter waves, LiDAR systems use short-wavelength electromagnetic waves (visible light, infrared rays, or ultraviolet rays), so they can detect the distance distribution of objects with high resolution.
  • Such a LiDAR system can be mounted on a moving object such as a car, a UAV (Unmanned Aerial Vehicle, so-called drone), or an AGV (Automated Guided Vehicle), and can be used as one of collision avoidance technologies.
  • an optical scanning device and an optical receiving device may be collectively referred to as an "optical device.”
  • a device used as an optical scanning device or an optical receiving device may also be referred to as an "optical device.”
  • light includes not only visible light (wavelength of about 400 nm to about 700 nm) but also electromagnetic waves including ultraviolet light (wavelength of about 10 nm to about 400 nm) and infrared light (wavelength of about 700 nm to about 1 mm). means.
  • ultraviolet light may be referred to as “ultraviolet light” and infrared light may be referred to as “infrared light.”
  • scanning with light means changing the direction of light.
  • One-dimensional scanning means changing the direction of light linearly along a direction that intersects the direction.
  • Tele-dimensional scanning means changing the direction of light two-dimensionally along a plane that intersects the direction.
  • FIG. 1 is a perspective view schematically showing the configuration of an optical scanning device 100.
  • the optical scanning device 100 includes a waveguide array including a plurality of waveguide elements 10.
  • Each of the plurality of waveguide elements 10 has a shape extending in the first direction (X direction in FIG. 1).
  • the plurality of waveguide elements 10 are regularly arranged in a second direction (Y direction in FIG. 1) that intersects the first direction.
  • the plurality of waveguide elements 10 transmit light in a third direction D3 intersecting a virtual plane parallel to the first and second directions while propagating the light in the first direction.
  • the first direction (X direction) and the second direction (Y direction) are perpendicular to each other, but they do not need to be perpendicular to each other.
  • the plurality of waveguide elements 10 are arranged at equal intervals in the Y direction, but they do not necessarily need to be arranged at equal intervals.
  • Each of the plurality of waveguide elements 10 includes a first mirror 30 and a second mirror 40 facing each other, and an optical waveguide layer 20 located between the mirrors 30 and 40.
  • Each of the mirrors 30 and 40 has a reflective surface that intersects with the third direction D3 at the interface with the optical waveguide layer 20.
  • the mirrors 30 and 40 and the optical waveguide layer 20 have shapes extending in the first direction (X direction).
  • the plurality of first mirrors 30 of the plurality of waveguide elements 10 may be a plurality of parts of an integrally configured mirror.
  • the plurality of second mirrors 40 of the plurality of waveguide elements 10 may be a plurality of parts of an integrally configured mirror.
  • the plurality of optical waveguide layers 20 of the plurality of waveguide elements 10 may be a plurality of parts of an optical waveguide layer that is integrally configured. At least, (1) each first mirror 30 is configured separately from other first mirrors 30; (2) each second mirror 40 is configured separately from other second mirrors 40; (3) Since each optical waveguide layer 20 is configured separately from other optical waveguide layers 20, a plurality of waveguides can be formed. "Separately configured" includes not only physically disposed with a space between them, but also separation with a material having a different refractive index in between.
  • the reflective surface of the first mirror 30 and the reflective surface of the second mirror 40 are substantially parallel to each other and face each other.
  • the first mirror 30 has a property of transmitting a part of the light propagating through the optical waveguide layer 20.
  • the first mirror 30 has a higher light transmittance than the second mirror 40 for the light. Therefore, a part of the light propagating through the optical waveguide layer 20 is emitted from the first mirror 30 to the outside.
  • Such mirrors 30 and 40 may be multilayer film mirrors formed of a multilayer film (sometimes referred to as a "multilayer reflective film") made of dielectric material, for example.
  • the phase of the light input to each waveguide element 10 is controlled, and the refractive index or thickness of the optical waveguide layer 20 in these waveguide elements 10 or the wavelength of the light input to the optical waveguide layer 20 is synchronized. By simultaneously changing the two directions, it is possible to realize two-dimensional scanning using light.
  • the present inventor analyzed the operating principle of the waveguide element 10 in order to realize such two-dimensional scanning. Based on the results, they succeeded in realizing two-dimensional scanning using light by driving a plurality of waveguide elements 10 synchronously.
  • each waveguide element 10 when light is input to each waveguide element 10, the light is emitted from the output surface of each waveguide element 10.
  • the exit surface is located on the opposite side of the reflective surface of the first mirror 30.
  • the direction D3 of the emitted light depends on the refractive index and thickness of the optical waveguide layer and the wavelength of the light.
  • at least one of the refractive index, thickness, and wavelength of each optical waveguide layer is synchronously controlled so that the light emitted from each waveguide element 10 is in approximately the same direction.
  • the X-direction component of the wave number vector of light emitted from the plurality of waveguide elements 10 can be changed.
  • the direction D3 of the emitted light can be changed along the direction 101 shown in FIG.
  • the lights emitted from the plurality of waveguide elements 10 are directed in the same direction, the emitted lights interfere with each other.
  • the direction in which the light strengthens each other due to interference can be changed. For example, when a plurality of waveguide elements 10 of the same size are lined up at equal intervals in the Y direction, a fixed amount of light having different phases is input to the plurality of waveguide elements 10. By changing the phase difference, the Y-direction component of the wave number vector of the emitted light can be changed.
  • the direction D3 in which the emitted lights strengthen each other due to interference can be changed along the direction 102 shown in FIG. .
  • two-dimensional scanning using light can be realized.
  • optical scanning device 100 The operating principle of the optical scanning device 100 will be explained below.
  • FIG. 2 is a diagram schematically showing an example of the cross-sectional structure of one waveguide element 10 and propagating light.
  • a direction perpendicular to the X direction and the Y direction shown in FIG. 1 is defined as the Z direction, and a cross section of the waveguide element 10 parallel to the XZ plane is schematically shown.
  • the first mirror 30 and the second mirror 40 are arranged with the optical waveguide layer 20 sandwiched therebetween.
  • the first mirror 30 has a first reflective surface 30s.
  • the second mirror 40 has a second reflective surface 40s that faces the first reflective surface 30s.
  • the light 20L introduced from one end of the optical waveguide layer 20 in the The light propagates within the optical waveguide layer 20 while being repeatedly reflected by the second reflecting surface 40s of the second mirror 40 provided on the lower surface of the second mirror 40.
  • the light transmittance of the first mirror 30 is higher than that of the second mirror 40. Therefore, part of the light can be output mainly from the first mirror 30.
  • the propagation angle of light means the angle of incidence on the interface between the mirror 30 or 40 and the optical waveguide layer 20.
  • Light incident on mirror 30 or mirror 40 at an angle closer to perpendicular can also propagate. That is, light incident on the interface at an angle smaller than the critical angle for total internal reflection can also propagate. Therefore, the group velocity of light in the direction of propagation of light is significantly lower than the speed of light in free space.
  • the waveguide element 10 has the property that the light propagation conditions change significantly with changes in the wavelength of the light, the thickness of the optical waveguide layer 20, and the refractive index of the optical waveguide layer 20.
  • a waveguide is called a "reflection waveguide” or a “slow light waveguide.”
  • the emission angle ⁇ of light emitted into the air from the waveguide element 10 is expressed by the following equation (1).
  • the direction of light emission can be changed by changing any one of the wavelength ⁇ of light in the air, the refractive index nw of the optical waveguide layer 20, and the thickness d of the optical waveguide layer 20. I can do it.
  • the emission angle is 0°.
  • the output angle changes to approximately 66°.
  • the emission angle changes to about 51°.
  • the emission angle changes to about 30°. In this way, by changing any one of the wavelength ⁇ of the light, the refractive index n w of the optical waveguide layer 20, and the thickness d of the optical waveguide layer 20, the direction of light emission can be greatly changed.
  • the optical scanning device 100 controls at least one of the wavelength ⁇ of the light input to the optical waveguide layer 20, the refractive index nw of the optical waveguide layer 20, and the thickness d of the optical waveguide layer 20. Controls the direction of light emission.
  • the wavelength ⁇ of the light may not be changed during operation and may be kept constant. In that case, optical scanning can be achieved with a simpler configuration.
  • the wavelength ⁇ is not particularly limited.
  • the wavelength ⁇ is a wavelength from 400 nm to 1100 nm (i.e., from visible light to near-infrared light) that provides high detection sensitivity with a photodetector or image sensor that detects light by absorbing it with general silicon (Si). may be included in the area.
  • the wavelength ⁇ may be included in the wavelength range of near-infrared light from 1260 nm to 1625 nm, where transmission loss is relatively small in an optical fiber or Si waveguide. Note that these wavelength ranges are just examples.
  • the wavelength range of the light used is not limited to the wavelength range of visible light or infrared light, and may be, for example, the wavelength range of ultraviolet light.
  • the optical scanning device 100 may include a first adjustment element that changes at least one of the refractive index, thickness, and wavelength of the optical waveguide layer 20 in each waveguide element 10.
  • the direction of light emission can be greatly changed by changing at least one of the refractive index nw , the thickness d, and the wavelength ⁇ of the optical waveguide layer 20. .
  • the emission angle of the light emitted from the mirror 30 can be changed in the direction along the waveguide element 10.
  • the optical waveguide layer 20 may include a liquid crystal material or an electro-optic material.
  • the optical waveguide layer 20 may be sandwiched between a pair of electrodes. By applying a voltage to the pair of electrodes, the refractive index of the optical waveguide layer 20 can be changed.
  • At least one actuator may be connected to at least one of the mirror 30 and the mirror 40.
  • the thickness of the optical waveguide layer 20 can be changed. If the optical waveguide layer 20 is formed from a liquid, the thickness of the optical waveguide layer 20 can be easily changed.
  • FIG. 3A is a diagram showing a cross section of a waveguide array that emits light in a direction perpendicular to the output surface of the waveguide array.
  • FIG. 3A also shows the amount of phase shift of light propagating through each waveguide element 10.
  • the phase shift amount is a value based on the phase of light propagating through the left-most waveguide element 10.
  • the waveguide array in this embodiment includes a plurality of waveguide elements 10 arranged at equal intervals.
  • a broken line arc indicates a wavefront of light emitted from each waveguide element 10.
  • the straight lines indicate wavefronts formed by interference of light.
  • the arrow indicates the direction of light emitted from the waveguide array (ie, the direction of the wave number vector).
  • FIG. 3A is a diagram showing a cross section of a waveguide array that emits light in a direction perpendicular to the output surface of the waveguide array.
  • FIG. 3A also shows the amount of phase shift of light propagating through each waveguide element 10.
  • the phase of light propagating through the optical waveguide layer 20 in each waveguide element 10 is the same.
  • the light is emitted in a direction (Z direction) perpendicular to both the arrangement direction of the waveguide elements 10 (Y direction) and the direction in which the optical waveguide layer 20 extends (X direction).
  • FIG. 3B is a diagram showing a cross section of a waveguide array that emits light in a direction different from the direction perpendicular to the output surface of the waveguide array.
  • the phases of light propagating through the optical waveguide layer 20 in the plurality of waveguide elements 10 differ by a fixed amount ( ⁇ ) in the arrangement direction.
  • the light is emitted in a direction different from the Z direction.
  • ⁇ the Y-direction component of the wave number vector of light can be changed.
  • the center-to-center distance between two adjacent waveguide elements 10 is p
  • the light emission angle ⁇ 0 is expressed by the following equation (2).
  • the direction of light emitted from the optical scanning device 100 is not parallel to either the XZ plane or the YZ plane. That is, ⁇ 0° and ⁇ 0 ⁇ 0°.
  • FIG. 4 is a perspective view schematically showing a waveguide array in three-dimensional space.
  • the thick arrows shown in FIG. 4 represent the direction of light emitted from the optical scanning device 100.
  • ⁇ is the angle between the light emission direction and the YZ plane.
  • ⁇ satisfies equation (1).
  • ⁇ 0 is the angle between the light emission direction and the XZ plane.
  • ⁇ 0 satisfies equation (2).
  • phase shifter that changes the phase of the light may be provided, for example, before introducing the light into the waveguide element 10.
  • the optical scanning device 100 includes a plurality of phase shifters connected to each of the plurality of waveguide elements 10, and a second adjustment element that adjusts the phase of light propagating through each phase shifter.
  • Each phase shifter includes a waveguide that connects directly or via another waveguide to an optical waveguide layer 20 in a corresponding one of the plurality of waveguide elements 10.
  • the second adjustment element changes the direction of the light emitted from the plurality of waveguide elements 10 (i.e., the third direction D3).
  • a plurality of arranged phase shifters will also be referred to as a "phase shifter array", similar to a waveguide array.
  • FIG. 5 is a schematic diagram of the waveguide array 10A and the phase shifter array 80A viewed from the normal direction (Z direction) of the light exit surface.
  • all phase shifters 80 have the same propagation characteristics and all waveguide elements 10 have the same propagation characteristics.
  • Each phase shifter 80 and each waveguide element 10 may have the same length or may have different lengths.
  • the amount of phase shift of each phase shifter can be adjusted by, for example, the drive voltage.
  • the length of each phase shifter 80 is changed in equal steps, it is possible to provide a phase shift in equal steps with the same driving voltage.
  • this optical scanning device 100 includes an optical splitter 90 that branches and supplies light to a plurality of phase shifters 80, a first drive circuit 70a that drives each waveguide element 10, and a first drive circuit 70a that drives each phase shifter 80. It further includes a second drive circuit 70b. Straight arrows in FIG. 5 indicate light input. Two-dimensional scanning can be realized by independently controlling the first drive circuit 70a and the second drive circuit 70b, which are provided separately. In this example, the first drive circuit 70a functions as one element of the first adjustment element, and the second drive circuit 70b functions as one element of the second adjustment element.
  • the first drive circuit 70a changes the angle of light emitted from the optical waveguide layer 20 by changing at least one of the refractive index and thickness of the optical waveguide layer 20 in each waveguide element 10.
  • the second drive circuit 70b changes the phase of light propagating inside the optical waveguide layer 20 by changing the refractive index of the optical waveguide layer 20 in each phase shifter 80.
  • the optical splitter 90 may be configured with a waveguide in which light propagates by total reflection, or may be configured with a reflective waveguide similar to the waveguide element 10.
  • each light may be introduced into the phase shifter 80.
  • a passive phase control structure can be used by adjusting the length of the waveguide up to the phase shifter 80.
  • a phase shifter that has the same function as phase shifter 80 and can be controlled by electrical signals may be used.
  • the phase may be adjusted before being introduced into the phase shifters 80 so that all the phase shifters 80 are supplied with light of the same phase.
  • Such adjustment makes it possible to simplify the control of each phase shifter 80 by the second drive circuit 70b.
  • An optical device having a configuration similar to the optical scanning device 100 described above can also be used as an optical receiving device. Details such as the operating principle and operating method of the optical device are disclosed in US Patent Application Publication No. 2018/0224709. The entire disclosure content of this document is incorporated herein by reference.
  • the optical device 100 can be manufactured, for example, by bonding together an upper structure including the mirror 30 and a lower structure including the mirror 40.
  • a sealing member such as ultraviolet curing resin or thermosetting resin may be used for bonding.
  • the optical waveguide layer 20 may include, for example, a liquid crystal material.
  • vacuum encapsulation may be utilized to inject liquid crystal material into optical device 100. By injecting the liquid crystal material into the space surrounded by the sealing member, vacuum leakage can be prevented when the liquid crystal material is injected.
  • FIG. 6A is a top view schematically showing the configuration of an optical device 99 according to a comparative example.
  • the optical device 99 shown in FIG. 6A includes an upper structure 99a, a lower structure 99b, and a plurality of optical waveguide regions (not shown), an alignment film, and a sealing member.
  • FIG. 6B is a top view schematically showing the configuration of the lower structure 99b shown in FIG. 6A.
  • FIG. 6C is a sectional view taken along the line VIC-VIC of the optical device 99 shown in FIG. 6A.
  • the upper structure 99a and the lower structure 99b are shown separated from each other to make the explanation easier to understand.
  • the upper structure 99a includes a substrate 50a, an electrode 62a, and a mirror 30.
  • the lower structure 99b includes a substrate 50b, an electrode 62b, a mirror 40, a dielectric layer 51, a plurality of optical waveguides 11, and a plurality of partition walls 73.
  • a region corresponding to the optical waveguide layer 20 described above is formed between the reflective surface 30s of the mirror 30 and the reflective surface 40s of the mirror 40. This region is referred to as the "optical waveguide region 20.”
  • a plurality of optical waveguide regions 20 are formed.
  • the number of optical waveguide regions 20 is six.
  • the alignment film 22 is provided on the reflective surface 30s of the mirror 30.
  • the sealing member 79 is provided on the dielectric layer 51 so as to surround the plurality of optical waveguide regions 20 and the plurality of partition walls 73. After the upper structure 99a and the lower structure 99b are bonded together using the seal member 79, a liquid crystal material is injected through the opening 79o of the seal member 79. Thereafter, the opening 79o is closed by the same member as the sealing member 79. Details of each component will be described later.
  • the reflective surface 30s of the mirror 30 has an alignment film such as a polyimide film subjected to an alignment process.
  • a membrane 22 is provided.
  • Orientation treatments include a rubbing method in which the film is rubbed in the desired orientation direction with a roll wrapped with nylon cloth, and a photo-alignment method in which the film is irradiated with polarized ultraviolet light whose polarization direction matches the desired orientation direction.
  • the rubbing method provides a strong alignment regulating force.
  • the photo-alignment method if light irradiation is possible, alignment treatment can be applied uniformly to the entire film even if the film has unevenness.
  • the orientation regulating force is weak.
  • the upper structure 99a has a flat surface corresponding to the reflective surface 30s of the first mirror 30, while the lower structure 99b is formed by the mirror 40, the dielectric layer 51, and the plurality of partition walls 73. It has an uneven surface formed thereon. While a flat polyimide film can be provided on the flat surface of the upper structure 99a, a flat polyimide film cannot be provided on the uneven surface of the lower structure 99b. Therefore, the flat surface of the upper structure 99a is provided with an alignment film 22 that has been subjected to an alignment treatment by a rubbing method, while such an alignment film is not provided on the uneven surface of the lower structure 99b.
  • the alignment regulating force in the plurality of optical waveguide regions 20 does not become so strong. Even if an alignment film subjected to an alignment process using a photoalignment method is provided on the uneven surface of the lower structure 99b, the alignment regulating force in the optical waveguide region 20 will not be significantly improved.
  • the width 79 Wennw of the opening 79 réelle in the Y direction is narrower than the width 20w in the Y direction of the plurality of optical waveguide regions 20, and is 1/5 of the width 20w in the Y direction of the plurality of optical waveguide regions 20. That's about it.
  • the width 20w of the plurality of optical waveguide regions 20 in the Y direction corresponds to the dimension in the Y direction of the smallest rectangle that includes all the plurality of optical waveguide regions 20 when viewed from the Z direction.
  • the area surrounded by the thick line shown in FIG. 6B represents the rectangle.
  • FIG. 7 is a photograph showing the results of an experiment in which a liquid crystal material was injected into an optical device 99 according to a comparative example through a narrow opening 79 filed under a vacuum of 0.5 Pa or less.
  • the width of the opening 79 filed in the Y direction is narrower than the width of the plurality of optical waveguide regions 20 in the Y direction.
  • the width of the opening 79 réelle was 600 ⁇ m, and the number of optical waveguide regions 20 was about 20.
  • FIG. 7 it can be seen that within the plurality of optical waveguide regions 20 surrounded by the sealing member 79, variations in alignment occur in the liquid crystal material due to flow alignment.
  • the present inventor discovered the above-mentioned problem and came up with an optical device according to an embodiment of the present disclosure that can suppress the occurrence of alignment variations due to flow alignment in a liquid crystal material.
  • the optical device according to this embodiment includes a first structure and a second structure.
  • the optical device according to this embodiment further includes one or more optical waveguide regions and a seal member surrounding the one or more optical waveguide regions between the first structure and the second structure.
  • the sealing member has an opening in a direction for injecting the liquid crystal material, the width of the opening being wider than the width of the one or more light guiding regions in that direction.
  • optical device that can suppress a decrease in the intensity of emitted light. Since the optical device functions not only as an optical scanning device but also as an optical receiving device as described later, the optical device can also suppress a decrease in the intensity of received light.
  • An optical device and a photodetection system including the optical device according to an embodiment of the present disclosure will be described below.
  • the optical device includes a first structure having a first surface, a second structure having a second surface opposite to the first surface, and the first surface of the first structure.
  • one or more optical waveguide regions that are located between the second surface of the second structure and include a liquid crystal material; a distance between the first structure and the second structure is fixed; a sealing member surrounding one or more optical waveguide regions, the sealing member having an opening for injecting the liquid crystal material.
  • the width of the opening in the first direction is larger than the width of the one or more optical waveguide regions in the first direction.
  • the optical device according to the second item is the optical device according to the first item, in which one or more spacers are provided in at least one of the opening of the sealing member and the periphery of the opening.
  • the distance between the first structure and the second structure can be made substantially constant regardless of the position within the opening and around the opening.
  • the one or more spacers include a plurality of spacers.
  • the effect of making the distance between the first structure and the second structure substantially constant can be further improved.
  • the optical device according to the fourth item is the optical device according to the third item, in which a gap between two adjacent spacers among the plurality of spacers is larger than the maximum width of each of the two spacers.
  • the optical device according to a fifth item is the optical device according to any one of the first to fourth items, wherein the width of the opening in the first direction is the width of the opening in the first direction of the one or more optical waveguide regions. It is 1.05 times or more the width in one direction.
  • the flow direction of the liquid crystal material becomes constant when the liquid crystal material is injected from the opening, and the liquid crystal material is aligned by flow alignment. It is possible to suppress the occurrence of variations.
  • the optical device according to a sixth item is the optical device according to any one of the first to fifth items, when viewed from a direction perpendicular to the first surface, the one or more optical waveguide regions;
  • the shortest distance to the opening is 0.2 times or less the width of the one or more optical waveguide regions in the first direction.
  • the optical device according to a seventh item is the optical device according to any one of the first to sixth items, wherein the one or more optical waveguide regions guide light in a second direction intersecting the first direction. make waves
  • liquid crystal material can be easily injected into one or more optical waveguide regions.
  • the optical device according to an eighth item is the optical device according to any one of the first to seventh items, in which the one or more optical waveguide regions are arranged in a plurality of optical waveguides arranged along the first direction. It is an area.
  • this optical device it is possible to change the direction of the emitted light emitted from the plurality of optical waveguide regions or the direction of the received light taken into the plurality of optical waveguide regions along the first direction.
  • the optical device according to the ninth item is the optical device according to the eighth item, further comprising a plurality of optical waveguides respectively connected to the plurality of optical waveguide regions.
  • Each optical waveguide includes a first grating for coupling the light into a corresponding one optical waveguide region.
  • light can be efficiently coupled from each optical waveguide to one corresponding optical waveguide region via the first grating.
  • the optical device according to the tenth item is the optical device according to the ninth item, in which each optical waveguide is arranged between the first structure and the second structure when viewed from a direction perpendicular to the first surface.
  • the second grating includes a portion that does not overlap with either one, and the second grating is provided in the portion.
  • light can be coupled from the outside to each optical waveguide via the second grating.
  • the optical device according to an eleventh item is the optical device according to any one of the eighth to tenth items, in which a plurality of phase shifters are connected to the plurality of optical waveguide regions, respectively, directly or via an optical waveguide. Furthermore, it is equipped with.
  • the direction of the emitted light or the direction of the received light can be changed along the first direction using the plurality of phase shifters.
  • the optical device according to the twelfth item is the optical device according to any one of the first to eleventh items, wherein the first structure includes a first mirror, and the second structure includes a second mirror.
  • the first surface has at least a portion of the reflective surface of the first mirror, and the second surface has at least a portion of the reflective surface of the second mirror.
  • a slow light waveguide is formed that includes a first mirror, a second mirror, and one or more optical waveguide regions.
  • the optical device according to the thirteenth item is the optical device according to any one of the first to twelfth items, wherein the one or more optical waveguide regions have a structure capable of adjusting the refractive index of the liquid crystal material. Equipped with By changing the refractive index of the liquid crystal material, the direction of light exiting from the one or more light guiding regions through the first structure or the second structure, or the first structure or the second structure can be changed. It is possible to change the direction of incidence of light introduced into the one or more optical waveguide regions via the second structure.
  • This optical device can function as an optical scanning device or an optical receiving device.
  • the optical device according to the fourteenth item is the optical device according to the thirteenth item, further comprising a pair of electrodes sandwiching the one or more optical waveguide regions. By applying a voltage to the pair of electrodes, it is possible to change the refractive index of the liquid crystal material.
  • the refractive index of the liquid crystal material can be changed by applying a voltage to a pair of electrodes.
  • all or part of a circuit, unit, device, member, or section, or all or part of a functional block in a block diagram may be, for example, a semiconductor device, a semiconductor integrated circuit (IC), or a large scale integration (LSI). ) may be implemented by one or more electronic circuits.
  • An LSI or IC may be integrated into one chip, or may be configured by combining a plurality of chips.
  • functional blocks other than the memory element may be integrated into one chip.
  • it is called LSI or IC, but the name changes depending on the degree of integration, and may be called system LSI, VLSI (very large scale integration), or ULSI (ultra large scale integration).
  • a field programmable gate array (FPGA), which is programmed after the LSI is manufactured, or a reconfigurable logic device that can reconfigure the connections inside the LSI or set up circuit sections inside the LSI can also be used for the same purpose.
  • FPGA field programmable gate array
  • all or part of the functions or operations of the circuit, unit, device, member, or section can be executed by software processing.
  • the software is recorded on one or more non-transitory storage media such as ROM, optical disk, hard disk drive, etc., and when the software is executed by a processor, the functions specified by the software are executed. It is executed by a processor and peripheral devices.
  • a system or apparatus may include one or more non-transitory storage media on which software is recorded, a processor, and required hardware devices, such as interfaces.
  • FIG. 8A is a top view schematically showing the configuration of an optical device according to exemplary embodiment 1 of the present disclosure.
  • 8B to 8D are diagrams schematically showing an example of a state in which upper components are removed from FIG. 8A.
  • 9A, FIG. 9B, and FIG. 9C are a sectional view taken along the line IXA-IXA, IXB-IXB, and IXC-IXC of FIG. 8A, respectively.
  • the optical device 100A shown in FIGS. 9A to 9C includes an upper structure 100a, a lower structure 100b, a plurality of optical waveguide regions 20, an alignment film 22, and a seal member 79.
  • the optical device 100A may further include a plurality of spacers 79s, as shown in FIG. 8D.
  • the optical device 100A can be manufactured, for example, by a process in which an upper structure 100a and a lower structure 100b are bonded together and a liquid crystal material is injected into the space sandwiched between them. A portion of the space filled with liquid crystal material is a plurality of optical waveguide regions 20 .
  • the side where the upper structure 100a is located is referred to as "upper”, and the side where the lower structure 100b is located is referred to as “lower”.
  • the terms “upper”, “lower”, “upper”, and “lower” do not limit the orientation of the optical device 100A during use, and the orientation of the optical device 100A is arbitrary.
  • the upper structure 100a is also referred to as the "first structure 100a”
  • the lower structure 100b is also referred to as the "second structure 100b”.
  • a portion of the surface of the upper structure 100a that faces the lower structure 100b is referred to as a "first surface.”
  • the portion facing the upper structure 100a is referred to as a "second surface.”
  • the first surface and the second surface face each other.
  • the first surface of the first structure 100a is also referred to as the "lower surface”
  • the second surface of the second structure 100b is also referred to as the "upper surface”.
  • the upper structure 100a includes a substrate 50a, an electrode 62a, and a mirror 30, as shown in FIGS. 9A to 9C.
  • An electrode 62a, a mirror 30, and an alignment film 22 are provided in this order on the substrate 50a.
  • the lower surface of the upper structure 100a includes at least a portion of the reflective surface 30s of the mirror 30.
  • the lower surface of the upper structure 100a may include the entire reflective surface 30s of the mirror 30 as shown in FIG. 9C, or if a part of the reflective surface 30s is exposed, it may include the part. You can leave it there.
  • the lower structure 100b includes a substrate 50b, an electrode 62b, a mirror 40, a dielectric layer 51, a plurality of partition walls 73, and a plurality of optical waveguides 11, as shown in FIGS. 8B to 9C.
  • An electrode 62b is provided on the substrate 50b.
  • a mirror 40 is provided on the electrode 62b.
  • the reflective surface 40s of the mirror 40 faces the reflective surface 30s of the mirror 30.
  • a dielectric layer 51 is provided on the mirror 40 .
  • a plurality of partition walls 73, a seal member 79, and a plurality of optical waveguides 11 are provided on the dielectric layer 51.
  • a plurality of spacers 79s may be further provided on the dielectric layer 51, as shown in FIG. 8D.
  • the plurality of optical waveguide regions 20 are located between the reflective surface 30s of the mirror 30 and the reflective surface 40s of the mirror 40.
  • a plurality of optical waveguide regions 20 arranged along the Y direction are formed between a plurality of partition walls 73.
  • the number of optical waveguide regions 20 is six, but is not limited to this number.
  • the number of optical waveguide regions 20 is an arbitrary number greater than or equal to one.
  • the portion of the optical waveguide region 20 and the mirror 30 that overlaps the optical waveguide region 20 when viewed from the Z direction, and the portion of the mirror 40 that overlaps the optical waveguide region 20 when viewed from the Z direction are A wave path 10 is formed.
  • the optical waveguide 10 functions as the aforementioned slow light waveguide.
  • the alignment film 22 is provided on the reflective surface 30s of the mirror 30 in the upper structure 100a before bonding the upper structure 100a and the lower structure 100b together.
  • the sealing member 79 and the plurality of spacers 79s are provided on the dielectric layer 51 in the lower structure 100b before the upper structure 100a and the lower structure 100b are bonded together.
  • the optical device 100A according to the first embodiment differs from the optical device 99 according to the comparative example in the size of the width 79 Wennw of the opening 79 réelle, as shown in FIGS. 6B and 8B to 8D.
  • the width 79 adoptedw of the opening 79 réelle in the Y direction is larger than the width 20w in the Y direction of the plurality of optical waveguide regions 20. big.
  • a plurality of partition walls 73 are provided on the dielectric layer 51.
  • the plurality of partition walls 73 are arranged at equal intervals along the Y direction.
  • Each of the plurality of partition walls 73 has a structure extending along the X direction.
  • a portion of the dielectric layer 51 located between the plurality of partition walls 73 when viewed from the Z direction is partially removed.
  • a plurality of portions of the reflective surface 40s of the mirror 40 are exposed.
  • the plurality of exposed portions are located at equal intervals along the Y direction.
  • Each of the plurality of exposed portions has a shape extending along the X direction.
  • the upper surface of the lower structure 100b has a plurality of exposed parts. As shown in FIG.
  • the portion of the dielectric layer 51 that has not been removed and the partition wall 73 directly above the portion form a convex portion extending in the X direction. Therefore, a plurality of convex portions located along the Y direction are formed on the mirror 40.
  • a plurality of recesses are formed between the plurality of protrusions.
  • the recess also has a structure extending along the X direction.
  • the depth of each recess that is, the height of the protrusions on both sides of each recess may be, for example, 1 ⁇ m or more and 10 ⁇ m or less.
  • the depth of the concave portion and the height of the convex portion mean respective dimensions measured along the Z direction in the figure.
  • a plurality of recesses are formed by the dielectric layer 51 and the plurality of partition walls 73, and the plurality of recesses define the plurality of optical waveguide regions 20.
  • the number of recesses is one, a single optical waveguide region 20 is formed.
  • the plurality of optical waveguide regions 20 are defined in regions where the plurality of recesses are located when viewed from the Z direction.
  • the optical waveguide region 20 is surrounded by the reflective surface 30s of the mirror 30, the reflective surface 40s of the mirror 40, and two adjacent convex portions.
  • Optical waveguide region 20 includes liquid crystal material 21 .
  • the refractive index of the optical waveguide region 20 is higher than the refractive index of the partition walls 73 and the dielectric layer 51.
  • the light propagating in the optical waveguide region 20 along the X direction does not leak to the convex portions located on both sides of the optical waveguide region 20. This is because the light is totally reflected at the interface between the optical waveguide region 20 and the convex portion.
  • the region where the convex portion exists can be referred to as a "non-waveguide region.”
  • a plurality of optical waveguide regions 20 and a plurality of non-waveguide regions are alternately located between mirror 30 and mirror 40 along the Y direction. This configuration corresponds to a plurality of optical waveguides 10 lined up in the Y direction.
  • the mirror 30 is located between the substrate 50a and a region where a plurality of optical waveguide regions 20 and a plurality of non-waveguide regions are alternately located along the Y direction.
  • the mirror 40 is located between the substrate 50b and a region where the plurality of optical waveguide regions 20 and the plurality of non-waveguide regions are alternately located along the Y direction.
  • Electrodes 62a and 62b face each other and indirectly sandwich the liquid crystal material 21 between them.
  • "Indirectly sandwiching" means sandwiching via another member.
  • a mirror 30, an alignment film 22, and a mirror 40 are arranged between the electrodes 62a and 62b.
  • the positional relationship between the electrode 62a and the mirror 30 may be reversed.
  • the alignment film 22 may be formed on the surface of the electrode 62a.
  • the positional relationship between the electrode 62b and the mirror 40 may be reversed.
  • the voltage applied to electrodes 62a and 62b the refractive index of liquid crystal material 21 can be adjusted.
  • the emission angle of the light emitted from the optical waveguide region 20 to the outside via the upper structure 100a changes.
  • the plurality of optical waveguides 11 are connected to the plurality of optical waveguide regions 20, respectively. Light is supplied from the optical waveguide 11 to the optical waveguide region 20 .
  • the optical waveguide 11 is located on the dielectric layer 51. Dielectric layer 51 is located between substrate 50b and optical waveguide 11. By adjusting the size of the dielectric layer 51 in the Z direction, light propagating through the optical waveguide 11 can be efficiently coupled to the optical waveguide 10.
  • the size of the dielectric layer 51 in the Z direction can be adjusted, for example, so that the optical waveguide 11 is located near the center of the optical waveguide region 20 in the Z direction.
  • the optical waveguide 11 is a waveguide that propagates light by total reflection. Therefore, the refractive index of the optical waveguide 11 is higher than the refractive index of the dielectric layer 51. Note that the optical waveguide 11 may be a slow light waveguide.
  • Each of the plurality of optical waveguides 11 includes a portion located between two adjacent partitions among the plurality of partitions 73.
  • each optical waveguide 11 includes a grating 15 for coupling light to a corresponding one optical waveguide region 20.
  • the grating 15 has a periodic structure along the X direction.
  • the propagation constant of the optical waveguide 11 is different from the propagation constant of the optical waveguide 10. Due to the grating 15, the propagation constant of the optical waveguide 11 is shifted by the reciprocal lattice of the periodic structure.
  • the reciprocal lattice of a periodic structure is a value obtained by multiplying the reciprocal of the period by 2 ⁇ . If the propagation constant of the optical waveguide 11 shifted by the reciprocal lattice matches the propagation constant of the optical waveguide 10, the light propagating through the optical waveguide 11 is efficiently coupled to the optical waveguide 10.
  • Each of the plurality of optical waveguides 11 includes a portion that overlaps with the substrate 50a but does not overlap with the substrate 50b when viewed from the Z direction.
  • Each optical waveguide 11 may include a grating 13 in the non-overlapping portion. For the same reason as above, when light is input through the grating 13, the input light can be coupled to the optical waveguide 11 with higher efficiency.
  • Each optical waveguide 11 may include a portion that overlaps with the substrate 50b but does not overlap with the substrate 50a, or may include a portion that does not overlap with both the substrate 50a and the substrate 50b.
  • the alignment film 22 is a rubbed alignment film whose alignment direction is defined by rubbing.
  • the alignment film 22 is provided on the reflective surface 30s of the mirror 30 included in the lower surface of the upper structure 100a.
  • the reflective surface 30s of the mirror 30 is a flat surface or an uneven surface having a height difference of less than 1 ⁇ m.
  • Liquid crystal material 21 covers the flat or contoured surface.
  • the alignment direction can be uniformly defined by rubbing.
  • the alignment film 22 has a strong alignment regulating force, no alignment film is provided on the upper surface of the lower structure 100b. Therefore, the alignment regulating force in the optical waveguide region 20 is not so strong. However, it is possible to maintain the orientation of the injected liquid crystal material 21 when no voltage is applied to the electrodes 62a and 62b.
  • the seal member 79 fixes the distance between the upper structure 100a and the lower structure 100b. As shown in FIGS. 8B to 8D, the sealing member 79 surrounds the plurality of optical waveguide regions 20 and the plurality of partition walls 73 when viewed from the Z direction.
  • the sealing member 79 includes a first portion that extends along the Y direction and straddles the plurality of optical waveguides 11, and a first portion that extends in the X direction from both ends of the first portion when viewed from the Z direction. and two second portions extending along.
  • the sealing member 79 further includes two third parts that extend toward each other along the Y direction from the ends of the two second parts, and two third parts that extend from the ends of the two third parts in the X direction. and two fourth portions each extending outwardly along.
  • the shape of the seal member 79 is not limited to the examples shown in FIGS. 8B to 8D.
  • the sealing member 79 has, for example, a roughly annular or elliptical annular shape, and a part of the shape may be open.
  • the sealing member 79 is arranged on the dielectric layer 51.
  • the upper surface of the seal member 79 is parallel to the XY plane.
  • the size in the Z direction of the portion of the sealing member 79 located directly above the dielectric layer 51 is either the same as the total thickness of the partition wall 73, the mirror 30, and the alignment film 22 (i.e., the dimension in the Z direction), or greater than the sum of the thicknesses.
  • the seal member 79 may be made of, for example, an ultraviolet curing resin or a thermosetting resin.
  • the material of the sealing member 79 does not need to be an ultraviolet curing resin or a thermosetting resin, as long as the material can maintain the distance between the substrates 50a and 50b for a long period of time.
  • the sealing member 79 has a wide opening 79 1958 for injecting the liquid crystal material 21.
  • the opening 79 1958 has a width 79 1958w in the Y direction.
  • the opening 79 1958 is defined by the ends of the two third portions and the fourth portion in the example shown in FIG. 8B, and by the two second portions in the example shown in FIGS. 8C and 8D.
  • the width 79 adoptedw of the opening 79schreib in the Y direction is narrower than the width in the Y direction of the region sandwiched by the two second parts.
  • the width 79droitw of the opening 79 1958 in the Y direction is the same as the width in the Y direction of the region sandwiched by the two second portions of the seal member 79.
  • the liquid crystal material 21 is flowed into the space surrounded by the seal member 79 through the opening 79 committee of the seal member 79 under a vacuum atmosphere. Thereafter, the opening 79 1958 is sealed with the same material as the seal member 79. The area sealed in this way is entirely filled with liquid crystal material 21.
  • the width 79 Washingtonw of the opening 79 filed in the Y direction is larger than the width 20w of the plurality of optical waveguide regions 20 in the Y direction.
  • both ends of the opening 79schreib are located outside of both ends of the plurality of optical waveguide regions 20.
  • the width 79 Washingtonw of the opening 79schreib in the Y direction is, for example, 1.05 times or more, more preferably 1.1 times or more, and even more preferably 1.3 times the width 20w of the plurality of optical waveguide regions 20 in the Y direction. obtain.
  • the direction in which the plurality of optical waveguide regions 20 guide light intersects more specifically, perpendicularly, to the direction in which the opening 79 Georgia has a width.
  • the flow direction of the liquid crystal material 21 is opposite to the direction in which the plurality of optical waveguide regions 20 guide light.
  • the flow direction of the liquid crystal material 21 is such a direction, the liquid crystal material 21 can be easily injected into the plurality of optical waveguide regions 20.
  • the sealing member 79 may have an opening in a portion near one of the two optical waveguide regions 20 located on both sides of the plurality of optical waveguide regions 20. good.
  • the opening has a width in the X direction.
  • the width of the opening in the X direction is wider than the width of the plurality of optical waveguide regions 20 in the X direction.
  • both ends of the opening 79 When viewed from the Y direction, both ends of the opening 79 Ltd are located outside of both ends of the plurality of optical waveguide regions 20.
  • the direction in which the plurality of optical waveguide regions 20 guide light is parallel to the direction in which the opening has a width. Even when the liquid crystal material 21 is injected through such an opening, the flow direction of the liquid crystal material 21 remains constant, and it is possible to suppress the occurrence of alignment variations in the liquid crystal material 21 due to flow orientation.
  • the shortest distance between the plurality of optical waveguide regions 20 and the opening 79 filed in the X direction is A configuration in which the distance 79d is made longer is also conceivable.
  • the area surrounded by the sealing member 79 becomes wider, so the optical device 99 becomes larger.
  • the shortest distance 79d corresponds to the shortest distance of the gap in the X direction between the smallest rectangle including all of the plurality of optical waveguide regions 20 and the above-mentioned third portion when viewed from the Z direction.
  • the width 79 proposedw of the opening 79 1958 is only widened in the Y direction, so even if the shortest distance 79d is short as shown in FIG. It is possible to suppress the occurrence of variations in orientation due to
  • the shortest distance 79d may be, for example, 0.2 times or less the width 20w of the plurality of optical waveguide regions 20 in the Y direction.
  • the shortest distance 79d is assumed to be zero. In this way, in the optical device 100A according to the first embodiment, the shortest distance 79d can be shortened, so that it is possible to suppress the increase in size of the optical device 100A.
  • a plurality of spacers 79s may be provided in the opening 79 réelle, as shown in FIG. 8D.
  • the number of spacers 79s is seven, but is not limited to this number.
  • the number of spacers 79s is an arbitrary number greater than or equal to one.
  • the plurality of spacers 79s are arranged along the Y direction.
  • the gap between two adjacent spacers 79s is larger than the maximum width of each of the two spacers 79s.
  • the gap may be, for example, 1.5 times or more, more preferably twice or more, the maximum width of each of the two spacers 79s.
  • the thicknesses of the plurality of optical waveguide regions 20 are not all the same, the emission angles of the light emitted from the plurality of optical waveguide regions 20 to the outside via the upper structure 100a are not uniform, and the intensity of the emitted light is may decrease.
  • the distance between the upper structure 100a and the lower structure 100b at the opening 79 Wenn of the sealing member 79 is approximately the same regardless of the position within the opening 79 réelle and around the opening 79 réelle. constant. Therefore, the decrease in the intensity of the emitted light as described above can be suppressed.
  • a plurality of spacers 79s are applied to the configuration shown in FIG. 8C, but a plurality of spacers 79s may be applied to the configuration shown in FIG. 8B.
  • a plurality of spacers 79s may be provided in the opening 79ée, may be provided around the opening 79ée, or may be provided in the opening 79ATOR and its surroundings.
  • the periphery of the opening 79ée is a range within a distance of 2000 ⁇ m from the opening 79 Ohio.
  • the size in the Z direction will also be referred to as "thickness.”
  • the substrate 50a may be formed, for example, from a SiO 2 layer.
  • the sizes of the substrate 50b in the X direction and the Y direction may be, for example, 8 mm and 20 mm, respectively, and the thickness of the substrate 50a may be, for example, 0.7 mm.
  • the electrode 62a may be formed, for example, from an ITO sputtered layer.
  • the thickness of the electrode 62a may be, for example, 50 nm.
  • Mirror 30 may be a multilayer reflective film.
  • the multilayer reflective film may be formed by alternately depositing and stacking five Nb 2 O layers and two SiO layers.
  • the thickness of the Nb 2 O 5 layer may be, for example, about 100 nm.
  • the thickness of the SiO 2 layer may be, for example, around 200 nm.
  • the mirror 30 has a total of 13 layers, for example, 7 Nb 2 O 5 layers and 6 SiO 2 layers.
  • the thickness of mirror 30 may be, for example, 1.9 ⁇ m.
  • the substrate 50b may be formed, for example, from a layer of SiO2 .
  • the size of the substrate 50b in the X direction and the Y direction can be, for example, both 15 mm.
  • the thickness of the substrate 50b may be, for example, 0.7 mm.
  • the electrode 62b may be formed, for example, from an ITO sputtered layer.
  • the thickness of the electrode 62b may be, for example, 50 nm.
  • Mirror 40 may be a multilayer reflective film.
  • the multilayer reflective film can be formed, for example, by alternately depositing and stacking five Nb 2 O layers and two SiO layers.
  • the thickness of the Nb 2 O 5 layer may be, for example, about 100 nm.
  • the thickness of the SiO 2 layer may be, for example, around 200 nm.
  • the mirror 40 has a total of 61 layers, for example, 31 Nb 2 O 5 layers and 30 SiO 2 layers.
  • the thickness of mirror 40 may be, for example, 9.1 ⁇ m.
  • the dielectric layer 51 can be formed, for example, from a deposited layer of SiO 2 .
  • the thickness of the SiO 2 vapor deposited layer may be, for example, about 1.0 ⁇ m.
  • the optical waveguide 11 may be formed, for example, from a Nb 2 O 5 deposited layer.
  • the thickness of the Nb 2 O 5 deposited layer may be, for example, about 300 nm.
  • a grating 15 and a grating 13 may be formed on the optical waveguide 11 .
  • the grating 15 has, for example, a duty ratio of 1:1 and a pitch of 640 nm.
  • the grating 13 has, for example, a duty ratio of 1:1 and a pitch of 680 nm.
  • Grating 15 and grating 13 may be formed by patterning using photolithography.
  • the size of the optical waveguide 11 in the Y direction may be, for example, 10 ⁇ m.
  • the partition wall 73 may be formed from a deposited layer of SiO 2 .
  • the thickness of the SiO 2 deposited layer may be, for example, 1.0 ⁇ m.
  • the size of the partition wall 73 in the Y direction may be, for example, 50 ⁇ m.
  • a portion of the dielectric layer 51 may be removed by patterning using photolithography, for example.
  • the thickness of the optical waveguide region 20 may be, for example, 2.0 ⁇ m.
  • the size of the optical waveguide region 20 in the Y direction may be, for example, 10 ⁇ m.
  • 5CB liquid crystal may be used as the material for the liquid crystal material 21.
  • polyimide may be used as the material for the alignment film 22.
  • the thickness of the polyimide alignment film is, for example, about 80 nm, and the variation in thickness can be 0 nm or more and 150 nm or less.
  • the polyimide alignment film is thick and its thickness is non-uniform. When light is incident on such a polyimide alignment film, light absorption and scattering occur.
  • the polyimide alignment film can be formed by applying a polyimide solution alignment material to the reflective surface 30s of the mirror 30, and drying and curing the alignment material.
  • the polyimide alignment film can also be provided on surfaces other than the reflective surface 30s of the mirror 30 in the upper structure 100a. Since the polyimide alignment film functions as an insulator, at least a portion of the electrode 62a is exposed without being covered with the polyimide alignment film for energization.
  • UV curing adhesive 3026E manufactured by ThreeBond may be used for the sealing member 79.
  • the seal member 79 is cured by ultraviolet irradiation with a wavelength of 365 nm and an energy density of 100 mJ/cm 2 , and the upper structure 100 a provided with the alignment film 22 and the lower structure 100 b are bonded together. By this bonding, an optical device 100A according to the first embodiment is obtained.
  • the spacer 79s may be made of silica or the same material as the seal member 79, for example.
  • the maximum width of the spacer 79s may be, for example, 0.5 ⁇ m or more and 10 ⁇ m or less.
  • substrates 50a and 50b may be made of a material other than SiO2 .
  • Substrates 50a and 50b may be, for example, inorganic substrates such as glass or sapphire, or resin substrates such as acrylic or polycarbonate. These inorganic substrates and resin substrates have translucency and can be used as the substrates 50a and 50b.
  • the reflectance of the mirror 30 from which light is emitted is, for example, 99.9%, and the reflectance of the mirror 40 from which light is not emitted is, for example, 99.99%.
  • This condition can be realized by adjusting the number of layers of the multilayer reflective film.
  • one layer has a refractive index of 2 or more, and the other layer has a refractive index of less than 2. If the difference between the two refractive indices is large, high reflectance can be obtained.
  • Examples of the layer having a refractive index of 2 or more include SiN x , AlN x , TiO x , ZrO x (1.7 ⁇ x ⁇ 2.0), NbO y , and TaO y (2.2 ⁇ y ⁇ 2.5). ) is formed from at least one selected from the group consisting of:
  • the layer having a refractive index of less than 2 is formed of, for example, at least one selected from the group consisting of SiO x and AlO x .
  • the refractive index of the dielectric layer 51 may be less than 2, for example.
  • the refractive index of each optical waveguide 11 can be, for example, 2 or more. If the difference between the two refractive indices is sufficiently large, evanescent light seeping out from each optical waveguide 11 into the dielectric layer 51 can be reduced.
  • the optical device of this embodiment differs from the optical device of Embodiment 1 in that the alignment film is provided not only on the surface of the first structure 100a but also on the surfaces of the second structure 100b and the sealing member 79. .
  • the alignment film provided on the surface of the first structure 100a is formed by a method other than rubbing.
  • the optical device according to the second embodiment will be described below, focusing on the points that are different from the optical device according to the first embodiment.
  • FIGS. 10A to 10C are cross-sectional views schematically showing the configuration of an optical device 100B according to exemplary embodiment 2 of the present disclosure.
  • 10A to 10C correspond to FIGS. 9A to 9C, respectively.
  • the structure of the optical device 100B viewed from the Z direction is similar to the structure shown in FIG. 8A, except that alignment films are also provided on the surfaces of the lower structure 100b and the seal member 79.
  • the optical device 100B shown in FIGS. 10A to 10C includes an upper structure 100a, a lower structure 100b, a plurality of optical waveguide regions 20, a first alignment film 22a, a second alignment film 22b, and a sealing member 79. Equipped with.
  • the first alignment film 22a has the same structure as the alignment film 22 described above.
  • the second alignment film 22b is an alignment film formed by a method other than rubbing.
  • the second alignment film 22b is provided on the upper surface, lower surface, and side surfaces of the lower structure 100b, and on the upper surface and side surfaces of the seal member 79. More specifically, the second alignment film 22b is exposed if the second alignment film 22b is not present among the substrate 50b, mirror 40, dielectric layer 51, partition 73, seal member 79, and optical waveguide 11. installed on the surface.
  • the second alignment film 22b may be, for example, a photo-alignment film whose alignment direction is defined by irradiation with polarized light.
  • the second alignment film 22b may be, for example, a film bonded to the surface of the second structure 100b via a siloxane bond, more specifically a monomolecular alignment film. Siloxane bonds improve the adhesion and coverage of monolayers. Monomolecular alignment films can be produced at low cost.
  • the second alignment film 22b is also provided on a surface other than the reflective surface 40s of the mirror 40 in the lower structure 100b.
  • the second alignment film 22b does not necessarily need to be provided on the surface of the lower structure 100b other than the reflective surface 40s of the mirror 40.
  • the upper surface of the lower structure 100b has a plurality of recesses having a depth of 1 ⁇ m or more and 10 ⁇ m or less.
  • Liquid crystal material 21 covers the plurality of recesses. It is not easy to form a rubbing alignment film for aligning the liquid crystal material in a specific direction on the surface of the second structure 100b having such a plurality of recesses.
  • the convex portions located on both sides of each concave portion become an obstacle to rubbing, and may cause unevenness in the alignment direction. Furthermore, the convex portion may be destroyed by rubbing, and the function of the optical waveguide region 20 as a waveguide may be impaired.
  • the alignment film 22b when the second alignment film 22b is formed by irradiation with polarized light, the alignment film 22b that aligns the liquid crystal material in a specific direction can be easily formed.
  • the convex portion does not have a shape that blocks polarized light from irradiating the alignment film.
  • a shape may be, for example, an inverted tapered shape in which the width increases as the distance from the reflective surface 40s of the mirror 40 increases.
  • the second alignment film 22b is thin and does not function as an insulating film, there is no problem in leaving the second alignment film 22b provided on the surface other than the reflective surface 40s of the mirror 40. Therefore, in manufacturing the optical device 100B, the step of removing the second alignment film 22b can be omitted. Depending on the application, the alignment film 22 provided on surfaces other than the reflective surface 40s of the mirror 40 may be removed.
  • the alignment regulating force in the optical waveguide region 20 is improved to some extent compared to the optical device 100A according to the first embodiment. can be done.
  • the optical device 100B according to the second embodiment when no voltage is applied to the electrodes 62a and 62b, the effect of maintaining the orientation of the liquid crystal material 21 injected into the plurality of optical waveguide regions 20 is improved. be able to.
  • the optical device 100B according to the second embodiment also provides the same effects as the optical device 100A according to the first embodiment.
  • a plurality of optical waveguide regions 20 are provided aligned in the Y direction.
  • Such an optical waveguide region 20 may be, for example, a single planar optical waveguide.
  • a modification of the optical device 100B according to the second embodiment will be described with reference to FIGS. 11A to 12C. The modification described below can also be applied to the optical device 100A according to the first embodiment.
  • the only difference between the optical device 100B according to the second embodiment and the optical device 100A according to the first embodiment is the presence or absence of the second alignment film 22b.
  • FIG. 11A is a diagram schematically showing an example of an optical device 110 according to this modification when viewed from the Z direction. However, in FIG. 11A, illustration of the second alignment film 22b is omitted.
  • FIGS. 11B to 11D are diagrams schematically showing an example of a state in which the upper structure 100a is removed from the structure shown in FIG. 11A.
  • the seal members 79 shown in FIGS. 11B to 11D are the same as the seal members 79 shown in FIGS. 8B to 8D, respectively.
  • the spacer 79s shown in FIG. 11D is the same as the spacer 79s shown in FIG. 8D. 12A, FIG. 12B, and FIG.
  • 12C are a sectional view taken along the line XIIA-XIIA, a sectional view taken along the line XIIB-XIIB, and a sectional view taken along the line XIIC-XIIC of FIG. 11A, respectively.
  • the upper structure 110a has the same structure as the upper structure 100a in the second embodiment.
  • the lower structure 110b unlike the lower structure 100b in the second embodiment, two partition walls 73 are arranged on both sides of one optical waveguide region 20, as shown in FIGS. 11B to 11D. ing.
  • the lower structure 100b has a relatively wide recess.
  • the reflective surface 40s of the mirror 40 is exposed over a relatively wide range extending along the X direction and the Y direction.
  • the size of the mirror 40 may be reduced so that the entire reflective surface 40s of the mirror 40 coincides with the exposed portion. That is, the exposed portion may be a part or the entire reflective surface 40s of the mirror 40. Therefore, it can be said that the upper surface of the lower structure 100b includes at least a portion of the reflective surface 40s of the mirror 40.
  • the recess is located between two protrusions extending in the X direction.
  • a planar optical waveguide is formed by the reflective surface 30s of the mirror 30, the reflective surface 40s of the mirror 40, and one optical waveguide region 20 located between them and extending along the X direction and the Y direction.
  • the optical waveguide region 20 is surrounded by two convex portions formed by the reflective surface 30s of the mirror 30, the reflective surface 40s of the mirror 40, and the partition wall 73.
  • the optical waveguide region 20 is filled with a liquid crystal material 21 containing a liquid crystal material.
  • the plurality of optical waveguides 11 are connected to the optical waveguide region 20 in the planar optical waveguide 10.
  • Light propagating through the plurality of optical waveguides 11 is coupled to the optical waveguide region 20 .
  • the combined light interferes within the optical waveguide region 20 to form a light beam.
  • the light beam formed within the optical waveguide region 20 is emitted to the outside via the mirror 30, the electrode 62a, and the substrate 50a.
  • the X-direction component and the Y-direction component of the wave number vector of the emitted light can be changed.
  • the second alignment film 22b when the second alignment film 22b is formed by rubbing, good alignment performance cannot be achieved particularly at the step portion due to the influence of the step portion at the edge of the recess.
  • the second alignment film 22b is formed by a method that does not rely on rubbing, such as irradiation with polarized light. Thereby, it is possible to form the second alignment film 22b having good alignment performance even in the step portion.
  • the optical waveguide 10 is a slow light waveguide.
  • the optical waveguide 10 does not need to be a slow light waveguide.
  • the optical waveguide 10 may be, for example, an optical waveguide that does not include the mirrors 30 and 40 and propagates light within the optical waveguide region 20 by total reflection at the surfaces of the substrate 50a and the substrate 50b.
  • the light propagating through the optical waveguide may be emitted to the outside from the end of the optical waveguide 10, for example, instead of through the substrate 50a or the substrate 50b.
  • FIG. 13 is a diagram showing a configuration example of an optical scanning device 100 in which elements such as an optical splitter 90, a waveguide array 10A, a phase shifter array 80A, and a light source 130 are integrated on a circuit board (for example, a chip).
  • Optical scanning device 100 also includes optical devices according to Embodiments 1 and 2 and variations thereof.
  • the light source 130 may be, for example, a light emitting device such as a semiconductor laser.
  • the light source 130 in this example emits light of a single wavelength whose wavelength in free space is ⁇ .
  • the optical splitter 90 branches the light from the light source 130 and introduces it into waveguides in a plurality of phase shifters.
  • an electrode 62A and a plurality of electrodes 62B are provided on the chip.
  • a control signal is supplied to the waveguide array 10A from the electrode 62A.
  • Control signals are sent from the plurality of electrodes 62B to the plurality of phase shifters 80 in the phase shifter array 80A, respectively.
  • the electrode 62A and the plurality of electrodes 62B may be connected to a control circuit (not shown) that generates the above control signal.
  • the control circuit may be provided on the chip shown in FIG. 13 or may be provided on another chip in the optical scanning device 100.
  • FIG. 14 is a schematic diagram showing how a light beam such as a laser is irradiated far from the optical scanning device 100 to perform a two-dimensional scan.
  • Two-dimensional scanning is performed by moving beam spot 310 horizontally and vertically.
  • a two-dimensional ranging image can be acquired by combining with the well-known TOF (Time of Flight) method.
  • the TOF method is a method of calculating the flight time of light and determining the distance by irradiating a laser and observing the reflected light from an object.
  • FIG. 15 is a block diagram showing a configuration example of a LiDAR system 300, which is an example of a light detection system capable of generating such a distance measurement image.
  • LiDAR system 300 includes an optical scanning device 100, a photodetector 400, a signal processing circuit 600, and a control circuit 500.
  • Photodetector 400 detects light emitted from optical scanning device 100 and reflected from an object.
  • the photodetector 400 may be, for example, an image sensor sensitive to the wavelength ⁇ of the light emitted from the optical scanning device 100, or a photodetector including a light receiving element such as a photodiode. Photodetector 400 outputs an electrical signal according to the amount of light it receives.
  • the signal processing circuit 600 calculates the distance to the object based on the electrical signal output from the photodetector 400, and generates distance distribution data.
  • the distance distribution data is data indicating a two-dimensional distribution of distances (ie, a distance measurement image).
  • Control circuit 500 is a processor that controls optical scanning device 100, photodetector 400, and signal processing circuit 600. The control circuit 500 controls the timing of irradiation of the light beam from the optical scanning device 100 and the timing of exposure and signal readout of the photodetector 400, and instructs the signal processing circuit 600 to generate a distance measurement image.
  • the frame rate for acquiring the distance measurement image can be selected from, for example, 60 fps, 50 fps, 30 fps, 25 fps, 24 fps, etc., which are commonly used in moving images.
  • the higher the frame rate the more frequently distance images are acquired, and obstacles can be detected with higher accuracy.
  • an image can be acquired every time the car moves approximately 28 cm at a frame rate of 60 fps.
  • an image can be acquired every time the car moves approximately 14 cm.
  • a frame rate of 180 fps an image can be acquired every time the car moves approximately 9.3 cm.
  • the time required to acquire one ranging image depends on the beam scanning speed. For example, in order to obtain an image with a resolution of 100 ⁇ 100 points at 60 fps, it is necessary to perform beam scanning for each point at 1.67 ⁇ s or less.
  • the control circuit 500 controls emission of the light beam by the optical scanning device 100 and signal accumulation/readout by the photodetector 400 at an operating speed of 600 kHz.
  • the optical devices according to Embodiments 1 and 2 and their modifications have almost the same configuration and can also be used as optical receiving devices.
  • the optical receiving device includes the same waveguide array 10A as the optical scanning device, and a first adjustment element that adjusts the direction of receivable light.
  • Each first mirror 30 of the waveguide array 10A transmits light that is incident from the third direction on the opposite side of the first reflective surface.
  • Each optical waveguide layer 20 of the waveguide array 10A propagates the light that has passed through the first mirror 30 in the second direction.
  • the first adjustment element changes at least one of the refractive index and thickness of the optical waveguide layer 20 in each waveguide element 10 and the wavelength of the light, so that the receivable light taken into each optical waveguide layer 20 is changed.
  • the direction can be changed.
  • the optical receiving device includes a plurality of phase shifters 80, or 80a and 80b, which are the same as the optical scanning device, and light that is output from the plurality of waveguide elements 10 through the plurality of phase shifters 80, or 80a and 80b.
  • a second adjustment element is provided that changes the phase difference between the two, the direction of the receivable light can be changed two-dimensionally.
  • an optical receiving device can be configured in which the light source 130 in the optical scanning device 100 shown in FIG. 13 is replaced with a receiving circuit.
  • the light is sent to the optical splitter 90 through the phase shifter array 80A, and finally collected in one place and sent to the receiving circuit.
  • the intensity of the light concentrated in one place can be said to represent the sensitivity of the optical receiving device.
  • the sensitivity of the optical receiving device can be adjusted by adjusting elements separately incorporated into the waveguide array and phase shifter array 80A. In the optical receiving device, for example in FIG. 4, the directions of the wave number vectors (thick arrows in the figure) are opposite.
  • the incident light has a light component in the direction in which the waveguide element 10 extends (X direction in the figure) and a light component in the arrangement direction of the waveguide element 10 (Y direction in the figure).
  • the sensitivity of the light component in the X direction can be adjusted by an adjustment element built into the waveguide array 10A.
  • the sensitivity of the optical component in the arrangement direction of the waveguide element 10 can be adjusted by an adjustment element incorporated in the phase shifter array 80A.
  • ⁇ and ⁇ 0 shown in FIG. 4 can be found from the optical phase difference ⁇ when the sensitivity of the optical receiving device is maximized, the refractive index nw and the thickness d of the optical waveguide layer 20. Thereby, the direction of incidence of light can be specified.
  • optical scanning device and optical receiving device in the embodiments of the present disclosure can be used, for example, as a lidar system mounted on a vehicle such as an automobile, a UAV, or an AGV.

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001117109A (ja) * 1999-10-21 2001-04-27 Matsushita Electric Ind Co Ltd 液晶表示装置の製造方法
WO2020059226A1 (ja) * 2018-09-19 2020-03-26 パナソニックＩｐマネジメント株式会社 光デバイスおよび光検出システム
WO2022044938A1 (ja) * 2020-08-31 2022-03-03 パナソニックＩｐマネジメント株式会社 光デバイスおよび光検出システム

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001117109A (ja) * 1999-10-21 2001-04-27 Matsushita Electric Ind Co Ltd 液晶表示装置の製造方法
WO2020059226A1 (ja) * 2018-09-19 2020-03-26 パナソニックＩｐマネジメント株式会社 光デバイスおよび光検出システム
WO2022044938A1 (ja) * 2020-08-31 2022-03-03 パナソニックＩｐマネジメント株式会社 光デバイスおよび光検出システム

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