WO2022044938A1 - 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
WO2022044938A1
WO2022044938A1 PCT/JP2021/030304 JP2021030304W WO2022044938A1 WO 2022044938 A1 WO2022044938 A1 WO 2022044938A1 JP 2021030304 W JP2021030304 W JP 2021030304W WO 2022044938 A1 WO2022044938 A1 WO 2022044938A1
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Prior art keywords
light
optical
alignment film
optical waveguide
optical device
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PCT/JP2021/030304
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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 CN202180056198.3A priority Critical patent/CN116261670A/zh
Priority to JP2022544509A priority patent/JP7678458B2/ja
Publication of WO2022044938A1 publication Critical patent/WO2022044938A1/ja
Priority to US18/163,277 priority patent/US20230185118A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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 
    • G02F1/03—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 ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect
    • G02F1/0305—Constructional arrangements
    • G02F1/0311—Structural association of optical elements, e.g. lenses, polarizers, phase plates, with the crystal
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical 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 
    • G02F1/011—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  in optical waveguides, not otherwise provided for in this subclass
    • G02F1/0115—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  in optical waveguides, not otherwise provided for in this subclass in optical fibres
    • 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
    • G02F1/133371—Cells with varying thickness of the liquid crystal layer
    • 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
    • G02F1/133555—Transflectors
    • 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
    • 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
    • G02F1/292—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 by controlled diffraction or phased-array beam steering
    • 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

  • This disclosure relates to optical devices and photodetection systems.
  • Patent Document 1 discloses a configuration in which scanning by light can be performed by using a driving 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 optical beam is guided to each antenna element by a waveguide, and the phase of the optical beam is shifted by a phase shifter. This makes it possible to change the amplitude distribution of the far-field radiation pattern.
  • a variable optical delay line ie, a phase shifter
  • Patent Document 3 describes a waveguide provided with an optical waveguide layer in which light is waveguideed inside, a first distributed Bragg reflector formed on the upper surface and the lower surface of the optical waveguide layer, and a waveguide for incidenting light in the waveguide.
  • a light deflection element including a light incident port and a light emitting port formed on the surface of the waveguide for emitting light incident from the light incident port and waveguide in the waveguide is disclosed.
  • One aspect of the present disclosure provides an optical device having a relatively simple configuration and low optical loss.
  • the optical device includes a first structure having a first surface, a second structure having a second surface facing the first surface, and the first surface of the first structure.
  • a rubbing alignment film that is located between the second surface and the second surface of the second structure, is provided on one or more optical waveguide regions containing a liquid crystal material, and is provided on the first surface to orient the liquid crystal material.
  • a first alignment film is provided, and (A) the second surface is in contact with the liquid crystal material without intervening through any of the alignment films, or (B) is provided on the second surface and is other than the rubbing alignment film. It is an alignment film and further includes a second alignment film for orienting the liquid crystal material.
  • the present disclosure may be implemented in recording media such as systems, appliances, methods, integrated circuits, computer programs or computer readable recording discs, systems, appliances, methods, integrated circuits, etc. It may be realized by any combination of a computer program and a recording medium.
  • the computer-readable recording medium may include a non-volatile recording medium such as a CD-ROM (Compact Disc-Read Only Memory).
  • the 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 arranged in one device, or may be separately arranged in two or more separated devices.
  • "device" can mean not only one device, but also a system of multiple devices.
  • 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 a 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 emission plane 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 emission plane of the waveguide array.
  • FIG. 4 is a perspective view schematically showing a waveguide array in a three-dimensional space.
  • FIG. 5 is a schematic view of the waveguide array and the phase shifter array as viewed from the normal direction (Z direction) of the light emitting surface.
  • FIG. 6A is a plan view schematically showing an example of an optical device according to the first embodiment of the present disclosure.
  • FIG. 6B is a diagram showing a state in which the upper component is removed from FIG. 6A.
  • FIG. 7A is a sectional view taken along line VIIA-VIIA of FIG. 6A.
  • FIG. 7B is a sectional view taken along line VIIB-VIIB of FIG. 6A.
  • FIG. 7C is a sectional view taken along line VIIC-VIIC of FIG. 6A.
  • FIG. 8A is a cross-sectional view schematically showing an example of an optical device according to the second embodiment of the present disclosure.
  • FIG. 8B is a cross-sectional view schematically showing an example of an optical device according to the second embodiment of the present disclosure.
  • FIG. 8C is a cross-sectional view schematically showing an example of an optical device according to the second embodiment of the present disclosure.
  • FIG. 9A is a diagram for explaining the second alignment film in the second embodiment.
  • FIG. 9B is a diagram for explaining the second alignment film in the second embodiment.
  • FIG. 9C is a diagram for explaining the second alignment film in the second embodiment.
  • FIG. 9D is a diagram for explaining the second alignment film in the second embodiment.
  • FIG. 9E is a diagram for explaining the second alignment film in the second embodiment.
  • FIG. 9A is a diagram for explaining the second alignment film in the second embodiment.
  • FIG. 9B is a diagram for explaining the second alignment film in the second embodiment.
  • FIG. 9C is a diagram
  • FIG. 10A is a diagram schematically showing how light is emitted from the optical device according to the first embodiment.
  • FIG. 10B is a diagram schematically showing how light is emitted from the optical device according to the second embodiment.
  • FIG. 11A is a plan view schematically showing an example of an optical device according to a modification of the second embodiment of the present disclosure.
  • FIG. 11B is a diagram showing a state in which the upper component is removed from FIG. 11A.
  • 12A is a sectional view taken along line XIIA-XIIA of FIG. 11A.
  • 12B is a sectional view taken along line XIIB-XIIB of FIG. 11A.
  • 12C is a sectional view taken along line XIIC-XIIC of FIG. 11A.
  • FIG. 13 is a diagram showing a configuration example of an optical scan device in which elements such as an optical turnout, a waveguide array, a phase shifter array, and a light source are integrated on a circuit board.
  • FIG. 14 is a schematic diagram showing a state in which a two-dimensional scan is executed by irradiating a light beam such as a laser at a distance from the light scanning device.
  • FIG. 15 is a block diagram showing a configuration example of a LiDAR system capable of generating a ranging image.
  • the present inventor has found that a conventional optical scanning device has a problem that it is difficult to scan a space with light without complicating the configuration of the device.
  • the present inventor paid attention to the above-mentioned problems in the prior art, and examined the configuration for solving these problems.
  • the present inventor has found that the above problem can be solved by using a waveguide element having a pair of facing mirrors 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 a part of the light propagating in the optical waveguide layer to the outside.
  • the direction (or emission 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 later. More specifically, by changing the refractive index, thickness, or wavelength, the component of the wave vector of the emitted light in the direction along the longitudinal direction of the optical waveguide layer can be changed. This realizes a one-dimensional scan.
  • a two-dimensional scan can be realized. More specifically, by giving an appropriate phase difference to the light supplied to a plurality of waveguide elements and adjusting the phase difference, it is possible to change the direction in which the light emitted from the plurality of waveguide elements strengthens each other. can. Due to the change in the phase difference, the component of the wave vector of the emitted light in the direction intersecting the longitudinal direction of the optical waveguide layer changes. This makes it possible to realize a two-dimensional scan. Even when performing a two-dimensional scan, it is not necessary 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. As described above, according to the embodiment of the present disclosure, it is possible to realize a two-dimensional scan by light 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. Means at least one that is done. In order to change the emission direction of light, any one of the refractive index, the thickness, and the wavelength may be controlled independently. Alternatively, any two or all of these three may be controlled to change the light emission direction. In each of the following embodiments, the wavelength of the light input to the optical waveguide layer may be controlled in place of or in addition to the control of the refractive index or the thickness.
  • the above basic principle can be applied not only to applications that emit light but also to applications that receive optical signals.
  • the direction of the receivable light can be changed one-dimensionally.
  • the phase difference of light is changed by a plurality of phase shifters connected to each of a plurality of waveguide elements arranged in one direction, the direction of receivable light can be changed two-dimensionally.
  • the optical scanning device and the optical receiving device can be used as an antenna in an optical detection system such as a LiDAR (Light Detection and Ringing) system. Since the LiDAR system uses short wavelength electromagnetic waves (visible light, infrared rays, or ultraviolet rays) as compared with a radar system using radio waves such as millimeter waves, it is possible to detect the distance distribution of an object with high resolution.
  • a LiDAR system can be mounted on a moving body such as an automobile, 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".
  • the device used for the optical scanning device or the optical receiving device may also be referred to as an "optical device”.
  • light refers to electromagnetic waves including not only visible light (wavelength of about 400 nm to about 700 nm) but also ultraviolet rays (wavelength of about 10 nm to about 400 nm) and infrared rays (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 by light means changing the direction of light.
  • One-dimensional scan means changing the direction of light linearly along a direction that intersects that 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 the optical scan device 100.
  • the optical scan 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) intersecting the first direction.
  • the plurality of waveguide elements 10 propagate the light in the first direction and emit the light in the third direction D3 intersecting the virtual plane parallel to the first and second directions.
  • the first direction (X direction) and the second direction (Y direction) are orthogonal to each other, but they do not have to be orthogonal to each other.
  • a plurality of waveguide elements 10 are arranged at equal intervals in the Y direction, but they do not necessarily have to be arranged at equal intervals.
  • Each of the plurality of waveguide elements 10 has a first mirror 30 and a second mirror 40 facing each other, and an optical waveguide layer 20 located between the mirror 30 and the mirror 40.
  • Each of the mirror 30 and the mirror 40 has a reflective surface intersecting the third direction D3 at the interface with the optical waveguide layer 20.
  • the mirror 30, the mirror 40, and the optical waveguide layer 20 have a shape 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 the mirror integrally configured.
  • the plurality of second mirrors 40 of the plurality of waveguide elements 10 may be a plurality of parts of the mirror integrally configured.
  • the plurality of optical waveguide layers 20 of the plurality of waveguide elements 10 may be a plurality of portions of the integrally configured optical waveguide layer. At least, (1) each first mirror 30 is configured separately from the other first mirror 30, and (2) each second mirror 40 is configured separately from the other second mirror 40. (3) Since each optical waveguide layer 20 is configured separately from the other optical waveguide layer 20, a plurality of waveguides can be formed.
  • the term "composed of separate bodies" includes not only the fact that they are physically arranged with a space apart, but also that they are separated by a material having a different refractive index between them.
  • the reflective surface of the first mirror 30 and the reflective surface of the second mirror 40 face each other almost in parallel.
  • 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 to the outside from the first mirror 30.
  • Such mirrors 30 and 40 can be, for example, multilayer mirrors formed of a multilayer film made of a dielectric (sometimes referred to as a "multilayer reflective film").
  • 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 changing the wavelengths at the same time, it is possible to realize a two-dimensional scan using light.
  • the present inventor analyzed the operating principle of the waveguide element 10 in order to realize such a two-dimensional scan. Based on the result, we succeeded in realizing a two-dimensional scan by light by driving a plurality of waveguide elements 10 in synchronization.
  • each waveguide element 10 when light is input to each waveguide element 10, light is emitted from the emission surface of each waveguide element 10.
  • the emission surface is located on the opposite side of the reflection surface of the first mirror 30.
  • the direction D3 of the emitted light depends on the refractive index, the thickness, and the wavelength of the light of the optical waveguide layer.
  • at least one of the refractive index, the thickness, and the wavelength of each optical waveguide layer is controlled synchronously so that the light emitted from each waveguide element 10 has substantially the same direction.
  • the X-direction component of the wave number vector of the 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 emitted light interferes with each other.
  • the direction in which the light strengthens due to interference can be changed. For example, when a plurality of waveguide elements 10 having the same size are arranged at equal intervals in the Y direction, light having a different phase is input to the plurality of waveguide elements 10 by a fixed amount. By changing the phase difference, the component in the Y direction of the wave vector of the emitted light can be changed.
  • the direction D3 in which the emitted light is strengthened by interference can be changed along the direction 102 shown in FIG. .. This makes it possible to realize a two-dimensional scan using light.
  • FIG. 2 is a diagram schematically showing an example of a cross-sectional structure of one waveguide element 10 and propagating light.
  • the directions perpendicular to the X and Y directions shown in FIG. 1 are defined as the Z direction, and a cross section parallel to the XZ plane of the waveguide element 10 is schematically shown.
  • the first mirror 30 and the second mirror 40 are arranged so as to sandwich the optical waveguide layer 20.
  • the first mirror 30 has a first reflecting surface 30s.
  • the second mirror 40 has a second reflecting surface 40s facing the first reflecting surface 30s.
  • the light 20L introduced from one end of the optical waveguide layer 20 in the X direction is the first reflecting surface 30s of the first mirror 30 provided on the upper surface (upper surface in FIG. 2) of the optical waveguide layer 20 and the lower surface (FIG. 2). It propagates in the optical waveguide layer 20 while repeating reflection by the second reflecting surface 40s of the second mirror 40 provided on the lower surface of No. 2.
  • the light transmittance of the first mirror 30 is higher than the light transmittance of the second mirror 40. Therefore, a part of the light can be mainly output from the first mirror 30.
  • the light propagation angle means the angle of incidence on the interface between the mirror 30 or the mirror 40 and the optical waveguide layer 20.
  • Light that is incident at an angle closer to perpendicular to the mirror 30 or the mirror 40 can also propagate. That is, light incident on the interface can also propagate at an angle smaller than the critical angle of total reflection. Therefore, the group velocity of light in the propagation direction 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 respect to changes in the wavelength of light, the thickness of the optical waveguide layer 20, and the refractive index of the optical waveguide layer 20.
  • a waveguide is referred to as a "reflecting waveguide” or a “slow light waveguide”.
  • the emission angle ⁇ of the light emitted from the waveguide element 10 into the air is expressed by the following equation (1).
  • the emission direction of the light is changed by changing any one of the wavelength ⁇ of the light in the air, the refractive index n w of the optical waveguide layer 20, and the thickness d of the optical waveguide layer 20. Can be done.
  • the emission angle is 0 °.
  • the emission angle changes to about 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 emission direction of the light can be significantly changed.
  • the optical scan device 100 controls at least one of the wavelength ⁇ of the light input to the optical waveguide layer 20, the refractive index n w of the optical waveguide layer 20, and the thickness d of the optical waveguide layer 20. Controls the emission direction of light.
  • the wavelength ⁇ of light may remain constant during operation without change. In that case, light scanning can be realized with a simpler configuration.
  • the wavelength ⁇ is not particularly limited.
  • the wavelength ⁇ is a wavelength of 400 nm to 1100 nm (that is, visible light to near-infrared light), which provides high detection sensitivity with a photodetector or image sensor that detects light by absorbing light with general silicon (Si). Can be included in the region.
  • the wavelength ⁇ may be included in the near infrared light wavelength range of 1260 nm to 1625 nm, which has a relatively low transmission loss in an optical fiber or Si waveguide. Note that these wavelength ranges are 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 scan device 100 may include a first adjusting 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 light emission direction can be significantly changed by changing at least one of the refractive index n w , 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-optical material.
  • the optical waveguide layer 20 may be sandwiched by 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 first mirror 30 and the second mirror 40.
  • the thickness of the optical waveguide layer 20 can be changed by changing the distance between the first mirror 30 and the second mirror 40 by at least one actuator. If the optical waveguide layer 20 is formed of 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 emission surface of the waveguide array.
  • FIG. 3A also shows the phase shift amount of the light propagating through each waveguide element 10.
  • the phase shift amount is a value based on the phase of the light propagating through the waveguide element 10 at the left end.
  • the waveguide array in this embodiment includes a plurality of waveguide elements 10 arranged at equal intervals.
  • the dashed arc indicates the wavefront of light emitted from each waveguide element 10.
  • the straight line shows the wavefront formed by the interference of light.
  • the arrows indicate the direction of the light emitted from the waveguide array (ie, the direction of the wave vector).
  • the phases of the light propagating in the optical waveguide layer 20 in each waveguide element 10 are the same.
  • the light is emitted in a direction (Z direction) perpendicular to both the arrangement direction (Y direction) of the waveguide element 10 and the direction (X direction) in which the optical waveguide layer 20 extends.
  • 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 emission plane of the waveguide array.
  • the phases of the light propagating in the optical waveguide layer 20 in the plurality of waveguide elements 10 are different by a fixed amount ( ⁇ ) in the arrangement direction.
  • the light is emitted in a direction different from the Z direction.
  • ⁇ the component in the Y direction of the wave vector of light can be changed.
  • the light emission angle ⁇ 0 is expressed by the following equation (2).
  • the direction of the light emitted from the optical scan device 100 is not parallel to 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 a three-dimensional space.
  • the thick arrow shown in FIG. 4 indicates the direction of the light emitted from the optical scanning device 100.
  • ⁇ is the angle formed by the light emission direction and the YZ plane.
  • ⁇ satisfies equation (1).
  • ⁇ 0 is the angle formed by the light emission direction and the XZ plane.
  • ⁇ 0 satisfies the equation (2).
  • phase shifter that changes the phase of the light may be provided before introducing the light into the waveguide element 10.
  • the optical scan device 100 includes a plurality of phase shifters connected to each of the plurality of waveguide elements 10, and a second adjusting element for adjusting the phase of light propagating through each phase shifter.
  • Each phase shifter includes a waveguide connected directly to or via another waveguide to the optical waveguide layer 20 in the corresponding one of the plurality of waveguide elements 10.
  • the second adjusting element changes the phase difference of the light propagating from the plurality of phase shifters to the plurality of waveguide elements 10, so that the direction of the light emitted from the plurality of waveguide elements 10 (that is, the third).
  • Direction D3 is changed.
  • a plurality of arranged phase shifters are also referred to as a “phase shifter array”.
  • FIG. 5 is a schematic view of the waveguide array 10A and the phase shifter array 80A as viewed from the normal direction (Z direction) of the light emitting 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 respective phase shift amounts can be adjusted by the drive voltage. Further, by adopting a structure in which the length of each phase shifter 80 is changed in equal steps, it is possible to give a phase shift in equal steps with the same drive voltage.
  • the optical scan device 100 drives an optical turnout 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 each phase shifter 80.
  • a second drive circuit 70b is further provided.
  • the straight arrow in FIG. 5 indicates the input of light.
  • Two-dimensional scanning can be realized by independently controlling the first drive circuit 70a and the second drive circuit 70b provided separately.
  • the first drive circuit 70a functions as one element of the first adjustment element
  • 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 the thickness of the optical waveguide layer 20 in each waveguide element 10.
  • the second drive circuit 70b changes the phase of the light propagating inside the waveguide 20 by changing the refractive index of the waveguide 20 in each phase shifter 80.
  • the optical turnout 90 may be configured by a waveguide in which light is propagated by total internal reflection, or may be configured by a reflection type waveguide similar to the waveguide element 10.
  • each light may be introduced into the phase shifter 80.
  • a passive phase control structure by adjusting the length of the waveguide leading up to the phase shifter 80 can be used.
  • a phase shifter that has the same function as the phase shifter 80 and can be controlled by an electric signal may be used.
  • the phase may be adjusted before being introduced into the phase shifter 80 so that the light having the same phase is supplied to all the phase shifters 80.
  • the control of each phase shifter 80 by the second drive circuit 70b can be simplified.
  • An optical device having the same configuration as the above-mentioned optical scan device 100 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 of this document is incorporated herein by reference.
  • the reflective surface 30s of the mirror 30 and the reflective surface 40s of the mirror 40 may be provided with an alignment film that orients the major axis of the liquid crystal molecule in the liquid crystal material in a specific direction.
  • the alignment film can be formed from a material that can achieve a relatively high alignment control force, such as polyimide.
  • the orientation direction of the alignment film can be defined by, for example, rubbing.
  • the alignment film formed by rubbing a material such as polyimide is thick and the thickness is non-uniform. When light is incident on such an alignment film, light absorption and scattering occur. As shown in FIG.
  • the optical waveguide layer 20 may have a non-negligible optical loss. According to the study of the present inventor, this light loss is about 50%.
  • An optical device can be manufactured by combining a first structure including the above-mentioned first mirror and the like and a second structure including the above-mentioned second mirror and the like. It corresponds to the above-mentioned optical waveguide layer between the surface of the first structure (hereinafter, also referred to as “first surface”) and the surface of the second structure (hereinafter, also referred to as “second surface”). A region is formed. The region is referred to as an "optical waveguide region".
  • the optical waveguide region can be formed from, for example, a liquid crystal material.
  • the optical waveguide region may include a material other than the liquid crystal material.
  • the first surface is provided with a first alignment film in which the orientation direction of the liquid crystal material is defined by rubbing, while the second surface is not provided with an alignment film. Therefore, the loss of propagating light can be suppressed as compared with the configuration in which the alignment film causing non-negligible light loss is provided on both the first surface and the second surface.
  • the first surface is provided with a first alignment film whose orientation direction is defined by rubbing, while the second surface is provided with a second alignment film whose orientation direction is defined regardless of rubbing. Is provided.
  • the second alignment film can be, for example, an alignment film bonded to the second surface via a siloxane bond between silicon (Si) and oxygen (O) (see, for example, Patent Document 4).
  • the orientation direction of the second alignment film can be defined by irradiation with polarized light, for example.
  • the light loss due to the second alignment film is negligibly small. Therefore, the loss of propagating light can be suppressed as compared with the configuration in which the rubbing alignment film is provided on both the first surface and the second surface.
  • the orientation direction of the liquid crystal material can be made more uniform.
  • the optical device includes a first structure having a first surface, a second structure having a second surface facing the first surface, and the first surface of the first structure.
  • a rubbing alignment film that is located between the second surface of the second structure and is provided on one or more optical waveguide regions containing a liquid crystal material and is provided on the first surface to orient the liquid crystal material. 1 Alignment film and.
  • the second surface comes into contact with the liquid crystal material without passing through any alignment film.
  • the optical device is provided on the second surface and is an alignment film other than the rubbing alignment film, and further includes a second alignment film for orienting the liquid crystal material.
  • the optical device according to the second item is a light alignment film in which the second alignment film is formed by irradiation with polarization in the optical device according to the first item.
  • the orientation direction of the alignment film can be specified without relying on rubbing.
  • the optical device according to the third item is a film containing a material in which the second alignment film is bonded to the second surface via a siloxane bond in the optical device according to the first or second item.
  • the adhesion and coverage of the second alignment film can be improved by the siloxane bond.
  • the film is a monolayer in the optical device according to the third item.
  • the optical device according to the fifth item is the optical device according to any one of the first to fourth items, wherein the second surface has one or more recesses having a depth of 1 ⁇ m or more and 10 ⁇ m or less.
  • the liquid crystal material covers the one or more recesses.
  • the liquid crystal material can be oriented by the first alignment film even if the recess has a depth of 1 ⁇ m or more and 10 ⁇ m or less.
  • the optical device according to the sixth item is the optical device according to the fifth item, wherein the one or more recesses are a plurality of recesses, and the one or more optical waveguide regions are a plurality of optical waveguide regions. Each of the plurality of optical waveguide regions covers each of the plurality of recesses.
  • This optical device can propagate light to multiple optical waveguide regions.
  • the optical device according to the seventh item is an optical device according to any one of the first to sixth items, wherein the first surface is a flat surface or an undulating surface having a height difference of less than 1 ⁇ m.
  • the liquid crystal material covers the flat surface or the undulating surface.
  • an alignment film whose orientation direction is defined by rubbing can be provided on the first surface having less undulations.
  • the optical device according to the eighth item is the optical device according to any one of the first to seventh items, wherein the first structure includes a first mirror having the first surface, and the second structure. Includes a second mirror with the second surface.
  • light can be propagated to the optical waveguide region regardless of the critical angle of total reflection by reflection by the first mirror and the second mirror.
  • the optical device according to the ninth item is the optical device according to the eighth item, in which the first mirror and the second mirror are both formed of a dielectric multilayer film.
  • the optical device according to the tenth item has a higher light transmittance than the second mirror in the optical device according to the ninth item.
  • light propagating in the optical waveguide region can be emitted to the outside through the first mirror.
  • the optical device according to the eleventh item is the optical device according to the tenth item, wherein the first structure includes a first electrode, and the second structure is a second electrode facing the first electrode. including.
  • the one or more optical waveguide regions are located between the first electrode and the second electrode.
  • this optical device by applying a voltage between the first electrode and the second electrode, light is emitted toward an external object located at a specific location, or the light reflected by the object is emitted. You can receive it.
  • the optical device according to the twelfth item further includes a plurality of phase shifters connected to the one or more optical waveguide regions directly or via another waveguide in the optical device according to the first item.
  • the light emitted from the optical device by the plurality of phase shifters whether one or more unidirectionally extending optical waveguide regions or one planar optical waveguide region.
  • the direction, or the direction of the light incident on the optical device can be changed.
  • the optical device according to the thirteenth item is the optical device according to the first item, in which the one or more optical waveguide regions are a plurality of optical waveguide regions.
  • the optical device further comprises a plurality of phase shifters connected to the plurality of optical waveguide regions either directly or via other waveguides.
  • the direction of light emitted from the optical device or the direction of light incident on the optical device can be changed by a plurality of phase shifters connected to each of the plurality of optical waveguides.
  • the photodetector system according to the fourteenth item includes the optical device according to any one of the first to thirteenth items, a photodetector that detects light emitted from the optical device and reflected from an object, and the like.
  • a signal processing circuit that generates distance distribution data based on the output of the photodetector is provided.
  • This light detection system can generate a distance image.
  • all or part of a circuit, unit, device, member or part, or all or part of a functional block in a block diagram is, for example, a semiconductor device, a semiconductor integrated circuit (IC), or an LSI (lage scale integration). ) Can be performed by one or more electronic circuits.
  • the LSI or IC may be integrated on one chip, or may be configured by combining a plurality of chips.
  • functional blocks other than the storage element may be integrated on one chip.
  • it is called LSI or IC, but the name changes depending on the degree of integration, and it may be called system LSI, VLSI (very large scale integration), or ULSI (ultra large scale integration).
  • Field Programmable Gate Array (FPGA) which is programmed after the LSI is manufactured, or reconfigurable logistic device, which can reconfigure the junction relation inside the LSI or set up the circuit partition inside the LSI, can also be used for the same purpose.
  • FPGA Field Programmable Gate Array
  • all or part of the function or operation of a circuit, unit, device, member or part can be executed by software processing.
  • the software is recorded on a non-temporary recording medium such as one or more ROMs, optical disks, hard disk drives, etc., and when the software is executed by a processor, the functions identified by the software It is executed by a processor and peripheral devices.
  • the system or device may include one or more non-temporary recording media on which the software is recorded, a processor, and the required hardware device, such as an interface.
  • FIG. 6A is a plan view schematically showing the configuration of the optical device 100A according to the first embodiment of the present disclosure.
  • FIG. 6B is a diagram showing a state in which the upper component is removed from FIG. 6A.
  • 7A, 7B, and 7C are a sectional view taken along line VIIA-VIIA, a sectional view taken along line VIIB-VIIB, and a sectional view taken along line VIIC-VIIC of FIG. 6A, respectively.
  • the optical device 100A includes an upper structure 100a, a lower structure 100b, a plurality of optical waveguide regions 20, and an alignment film 22.
  • the optical device 100A can be manufactured, for example, by a process of laminating an upper structure 100a and a lower structure 100b and injecting a liquid crystal material into a space sandwiched between them. A part of the space into which the liquid crystal material is injected is the optical waveguide region 20.
  • the side where the upper structure 100a is located is referred to as "upper”
  • 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 when used, and the orientation of the optical device 100A is arbitrary.
  • the upper structure 100a is also referred to as a "first structure 100a”
  • the lower structure 100b is also referred to as a "second structure 100b".
  • the portion facing 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 a “lower surface”
  • the second surface of the second structure 100b is also referred to as an “upper surface”.
  • the superstructure 100a in the present embodiment includes a substrate 50a, electrodes 62a, and a mirror 30.
  • An electrode 62a, a mirror 30, and an alignment film 22 are provided on the substrate 50a in this order.
  • the lower structure 100b in the present embodiment includes a substrate 50b, an electrode 62b, a mirror 40, a dielectric layer 51, a plurality of partition walls 73, a sealing member 79, and a plurality of optical waveguides 11.
  • 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 sealing member 79, and a plurality of optical waveguides 11 are provided on the dielectric layer 51.
  • the plurality of optical waveguide regions 20 in the present embodiment are located between the reflecting surface 30s of the mirror 30 and the reflecting surface 40s of the mirror 40.
  • six optical waveguide regions 20 arranged along the Y direction are formed between the plurality of partition walls 73.
  • the number of the optical waveguide regions 20 is not limited to 6, and may be any number of 1 or more.
  • the optical waveguide region 20, the portion of 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 form an optical waveguide.
  • the optical waveguide functions as the slow light waveguide described above.
  • the alignment film 22 in the present embodiment is provided on the reflective surface 30s of the mirror 30 in the upper structure 100a before the upper structure 100a and the lower structure 100b are bonded together.
  • optical device 100A The configuration of the optical device 100A according to this embodiment will be described in detail below.
  • the substrate on which light is emitted has translucency. Both the substrates 50a and 50b may have translucency.
  • the electrode on which light is emitted has translucency. Both the electrodes 62a and 62b may have translucency. At least one of the electrodes 62a and 62b can be formed, for example, from a transparent electrode. In the example shown in FIGS. 6A to 7C, light is emitted from the optical waveguide 10 via the electrodes 62a and the substrate 50a in the superstructure 100a.
  • the plurality of partition walls 73 are provided on the dielectric layer 51.
  • the plurality of partition walls 73 are arranged in the Y direction.
  • Each of the plurality of partition walls 73 has a structure extending along the X direction.
  • a part of the dielectric layer 51 located between the plurality of partition walls 73 when viewed from the Z direction is removed.
  • a plurality of portions of the reflective surface 40s of the mirror 40 are exposed. Multiple exposed parts are lined up in the Y direction.
  • Each of the plurality of exposed portions has a shape extending along the X direction.
  • FIG. 7C the portion of the dielectric layer 51 that has not been removed and the partition wall 73 immediately above the dielectric layer 51 form a convex portion extending in the X direction.
  • a plurality of convex portions arranged in the Y direction are formed on the mirror 40.
  • a plurality of concave portions are formed between the plurality of convex portions.
  • 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, can be, for example, 1 ⁇ or more and 10 ⁇ m or less.
  • the depth of the concave portion and the height of the convex portion mean the respective dimensions measured along the Z direction in the drawing.
  • the dielectric layer 51 and the plurality of partition walls 73 form a plurality of recesses, and the recesses define a plurality of optical waveguide regions 20. When the number of recesses is singular, a single optical waveguide region 20 is formed in the recesses.
  • the plurality of optical waveguide regions 20 are defined as regions in which a plurality of recesses are located when viewed from the Z direction.
  • the optical waveguide region 20 is surrounded by the reflecting surface 30s of the mirror 30, the reflecting surface 40s of the mirror 40, and two adjacent convex portions.
  • the optical waveguide region 20 includes a dielectric member 21.
  • the dielectric member 21 is made of a liquid crystal material.
  • the refractive index of the optical waveguide region 20 is higher than that of the partition wall 73 and the dielectric layer 51.
  • the light propagating in the optical waveguide region 20 does not leak to the convex portions located on both sides of the optical waveguide region 20. This is because the light propagating in the optical waveguide region 20 is totally reflected at the interface between the optical waveguide region 20 and the convex portion.
  • a region in which a convex portion exists can be referred to as a "non-waveguided region".
  • a plurality of optical waveguide regions 20 and a plurality of non-waveguide regions are alternately arranged in the Y direction between the mirror 30 and the mirror 40. This configuration corresponds to a plurality of optical waveguides 10 arranged in the Y direction.
  • the mirror 30 is located between a region in which a plurality of optical waveguide regions 20 and a plurality of non-waveguide regions are alternately arranged in the Y direction and a substrate 50a.
  • the mirror 40 is located between a region in which a plurality of optical waveguide regions 20 and a plurality of non-waveguide regions are alternately arranged in the Y direction and a substrate 50b.
  • the electrodes 62a and 62b face each other and indirectly sandwich the dielectric member 21. "Indirectly sandwiching" means sandwiching through another member.
  • the mirror 30, the alignment film 22, and the 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 the electrodes 62a and 62b the refractive index of the dielectric member 21 can be adjusted.
  • the emission angle of the light emitted to the outside from the optical waveguide 10 changes.
  • the seal member 79 fixes the distance between the upper structure 100a and the lower structure 100b. As shown in FIG. 6B, the seal member 79 surrounds the plurality of optical waveguides 10 and the plurality of partition walls 73 when viewed from the Z direction.
  • the seal member 79 includes a portion extending along the Y direction and a portion extending along the X direction from both sides of the portion.
  • the seal member 79 is arranged on the dielectric layer 51, and a portion extending along the Y direction is provided so as to straddle the plurality of optical waveguides 11.
  • the upper surface of the seal member 79 is parallel to the XY plane.
  • the size of the portion of the sealing member 79 located directly above the dielectric layer 51 in the Z direction is the same as or the total thickness of the partition wall 73, the mirror 30, and the alignment film 22 (that is, the dimension in the Z direction). Greater than the total thickness.
  • the seal member 79 may be formed of, for example, an ultraviolet curable resin or a thermosetting resin.
  • the material of the sealing member 79 does not need to be an ultraviolet curable resin or a thermosetting resin as long as the distance between the substrate 50a and the substrate 50b can be maintained for a long period of time.
  • the liquid crystal material constituting the dielectric member 21 can be injected into the space surrounded by the seal member 79, for example, by vacuum injection. By injecting the liquid crystal material into the space, it is possible to prevent vacuum leakage when the liquid crystal material is injected.
  • the plurality of optical waveguides 11 are each connected to the plurality of optical waveguide regions 20. 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.
  • the dielectric layer 51 is located between the substrate 50b and the optical waveguide 11.
  • 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 internal reflection. Therefore, the refractive index of the optical waveguide 11 is higher than that of the dielectric layer 51.
  • the optical wave guide 11 may be a slow light waveguide.
  • Each of the plurality of optical waveguides 11 includes a portion located between two adjacent partition walls among the plurality of partition walls 73. As shown in FIGS. 6B and 7A, each of the plurality of optical waveguides 11 may include a grating 15 having a periodic structure along the X direction at the portion. 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 the 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.
  • the liquid crystal material is injected from the sealing port 79o shown in FIG. 6B. After injecting the liquid crystal material, the sealing port 79o is closed by the same member as the sealing member 79. The area sealed in this way is entirely filled with the liquid crystal material.
  • the alignment film 22 is a rubbing alignment film whose orientation direction is defined by rubbing.
  • the orientation direction of the alignment film can be defined by rubbing the alignment film in a predetermined direction with a roll wrapped with a nylon cloth.
  • the alignment film 22 is provided on the reflective surface 30s of the mirror 30 included in the lower surface of the superstructure 100a.
  • the upper surface of the lower structure 100b is in contact with the dielectric member 21 without passing through any of the alignment films.
  • 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.
  • the dielectric member 21 covers a flat or undulating surface.
  • the rubbing alignment film has a higher alignment control force than the photo-alignment film described later. Therefore, the liquid crystal material can be effectively oriented only by providing the rubbing alignment film on the reflective surface 30s of the mirror 30.
  • the alignment film 22 is provided on the reflecting surface 30s of the mirror 30, but is not provided on the reflecting surface 40s of the mirror 40. Therefore, in the optical waveguide 10, even if light propagates while being multiple-reflected by the reflecting surface 30s and the reflecting surface 40s, the loss of the propagated light is about half that of the configuration in which the rubbing alignment films are provided on the upper and lower reflecting surfaces. Can be reduced to.
  • the size in the Z direction is also referred to as "thickness”.
  • the substrate 50a can be formed from, for example, two layers of SiO.
  • the size of the substrate 50b in the X and Y directions 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 can be formed from, for example, an ITO sputtered layer.
  • the thickness of the electrode 62a can be, for example, 50 nm.
  • the mirror 30 can be a multilayer reflective film.
  • the multilayer reflective film can be formed by alternately depositing and laminating Nb 2 O 5 layers and SiO 2 layers.
  • the thickness of the Nb 2 O 5 layer can be, for example, about 100 nm.
  • the thickness of the SiO 2 layer can be, for example, about 200 nm.
  • the mirror 30 has, for example, 7 layers of Nb 2 O 5 layers and 6 layers of SiO 2 layers for a total of 13 layers.
  • the thickness of the mirror 30 can be, for example, 1.9 ⁇ m.
  • the substrate 50b can be formed from, for example, two layers of SiO.
  • the size of the substrate 50b in the X and Y directions can be, for example, both 15 mm.
  • the thickness of the substrate 50b can be, for example, 0.7 mm.
  • the electrode 62b can be formed from, for example, an ITO sputtered layer.
  • the thickness of the electrode 62b can be, for example, 50 nm.
  • the mirror 40 can be a multilayer reflective film.
  • the multilayer reflective film can be formed, for example, by alternately depositing and laminating Nb 2 O 5 layers and SiO 2 layers.
  • the thickness of the Nb 2 O 5 layer can be, for example, about 100 nm.
  • the thickness of the SiO 2 layer can be, for example, about 200 nm.
  • the mirror 40 has, for example, 31 layers of Nb 2 O 5 layers and 30 layers of SiO 2 layers for a total of 61 layers.
  • the thickness of the mirror 40 can be, for example, 9.1 ⁇ m.
  • the dielectric layer 51 may be formed from, for example, a SiO 2 thin-film deposition layer.
  • the thickness of the SiO 2 thin-film deposition layer may be, for example, about 1.0 ⁇ m.
  • the optical waveguide 11 can be formed from, for example, an Nb 2 O 5 vapor deposition layer.
  • the thickness of the Nb 2 O 5 thin-film deposition layer can 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.
  • the grating 15 and the grating 13 can be formed by patterning by a photolithography method.
  • the size of the optical waveguide 11 in the Y direction can be, for example, 10 ⁇ m.
  • the partition wall 73 may be formed from a SiO 2 vapor deposition layer.
  • the thickness of the SiO 2 thin-film deposition layer can be, for example, 1.0 ⁇ m.
  • the size of the partition wall 73 in the Y direction can be, for example, 50 ⁇ m.
  • a part of the dielectric layer 51 can be removed by patterning by, for example, a photolithography method.
  • the thickness of the optical waveguide region 20 can be, for example, 2.0 ⁇ m.
  • the size of the optical waveguide region 20 in the Y direction can be, for example, 10 ⁇ m.
  • a 5CB liquid crystal display can be used as the material of the dielectric member 21.
  • polyimide may be used as the material of 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 an alignment material of a polyimide solution to the reflective surface 30s of the mirror 30 and drying and curing the polyimide solution.
  • the polyimide alignment film may be provided on the surface of the superstructure 100a other than the reflective surface 30s of the mirror 30. Since the polyimide alignment film functions as an insulator, at least a part of the electrode 62a is exposed for energization without being covered with the polyimide alignment film.
  • an ultraviolet curable adhesive 3026E manufactured by ThreeBond can be used for the sealing member 79.
  • the seal member 79 is cured by irradiation with ultraviolet rays having a wavelength of 365 nm and an energy density of 100 mJ / cm 2 , and the upper structure 100a provided with the alignment film 22 and the lower structure 100b are bonded together. By this bonding, the optical device 100A according to the present embodiment is obtained.
  • the substrates 50a and 50b may be formed of a material other than SiO 2 .
  • the substrates 50a and 50b may be, for example, an inorganic substrate such as glass or sapphire, or a resin substrate such as acrylic or polycarbonate. Since these inorganic substrates and resin substrates have translucency, they 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 indexes is large, a high reflectance can be obtained.
  • the layers having a refractive index of 2 or more are, for example, 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 from, for example, at least one selected from the group consisting of SiO x and AlO x .
  • the refractive index of the dielectric layer 51 can be, for example, less than 2.
  • the refractive index of each optical waveguide 11 can be, for example, 2 or more. If the difference between the two refractive indexes is sufficiently large, the evanescent light exuding from each optical waveguide 11 to the dielectric layer 51 can be reduced.
  • the optical device of the present embodiment is different from the optical device of the first embodiment in that the alignment film is provided not only on the surface of the first structure 100a but also on the surface of the second structure 100b. However, unlike the alignment film provided on the surface of the first structure 100a, the alignment film provided on the surface of the second structure 100b is formed by a method other than rubbing.
  • the optical device of the present embodiment will be described with a focus on the points different from those of the first embodiment.
  • FIGS. 8A to 8C are cross-sectional views schematically showing an example of the optical device 100B according to the present embodiment.
  • 8A to 8C correspond to FIGS. 7A to 7C, respectively. That is, FIGS. 8A to 8C are a sectional view taken along line VIIA-VIIA, a sectional view taken along line VIIB-VIIB, and a sectional view taken along line VIIC-VIIC in FIG. 6A, respectively.
  • the structure of the optical device 100B viewed from the Z direction is the same as the structure shown in FIG. 6A, except that an alignment film is also provided on the surface of the lower structure 100b. In the example shown in FIGS.
  • the superstructure 100a includes a first alignment film 22a having the same structure as the alignment film 22 described above.
  • the lower structure 100b includes a second alignment film 22b formed by a method other than rubbing.
  • the second alignment film 22b is provided on the upper surface, the lower surface, and the side surface of the lower structure 100b. More specifically, the second alignment film 22b is exposed if the second alignment film 22b is not present among the substrate 50b, the mirror 40, the dielectric layer 51, the partition wall 73, the sealing member 79, and the optical waveguide 11. It is provided on the surface.
  • the second alignment film 22b in the present embodiment is an alignment film other than the rubbing alignment film.
  • the alignment film 22b may be, for example, a photoalignment film whose orientation 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, and more specifically, a single molecule alignment film.
  • the siloxane bond improves the adhesion and coverage of the monolayer.
  • the monomolecular alignment film can be produced at low cost.
  • the second alignment film 22b is provided on the surface of the lower structure 100b other than the reflective surface 40s of the mirror 40 for the convenience of manufacturing the optical device 100B. However, it is not always necessary to provide the second alignment film 22b on the surface of the lower structure 100b other than the reflecting 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.
  • the dielectric member 21 covers a plurality of recesses. It is not easy to form a rubbing alignment film that orients 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 interfere with rubbing, and unevenness may occur in the orientation direction. Further, the convex portion may be destroyed by the 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 orients the liquid crystal material in a specific direction can be easily formed. It is desirable that the convex portion does not have a shape that blocks the irradiation of the alignment film with polarized light. Such a shape may be, for example, a reverse taper shape in which the width becomes wider as the distance from the reflecting surface 40s of the mirror 40 increases.
  • the single molecule alignment film is thinner and has a uniform thickness as compared with the polyimide alignment film.
  • the thickness of the monomolecular alignment film is about 2 nm, which is the molecular size. Even if light is incident on such a monomolecular alignment film, almost no light absorption or scattering occurs. Therefore, as shown in FIG. 2, even if the light is multiple-reflected and propagates in the optical waveguide region 20 along the X direction, the light is hardly absorbed or scattered by the single molecule alignment film. As a result, the loss of propagating light can be suppressed.
  • the second alignment film 22b is thin and does not function as an insulating film, there is no problem even if the second alignment film 22b provided on the surface other than the reflective surface 40s of the mirror 40 is left. Therefore, in the production of 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 the surface other than the reflective surface 40s of the mirror 40 may be removed.
  • FIGS. 9A to 9E are diagrams for explaining an example of the second alignment film 22b in the second embodiment.
  • FIG. 9A schematically shows a state in which the lower structure 100b is immersed in a solution 23 containing at least a silane compound.
  • a solution 23 containing at least a silane compound is brought into contact with the lower structure 100b and the silane compound is chemically adsorbed to form a film bonded via a siloxane bond.
  • the elliptical portion 23m 1 represents a siloxane bond
  • the thin and long portion 23m 2 represents a carbon-hydrogen bond
  • the thick and short portion 23m 3 represents other bonds.
  • the excess silane compound that has not been chemically adsorbed is dissolved in the cleaning liquid 24 and removed, so that the above film becomes a monomolecular film 22b0 bonded via a siloxane bond.
  • the monolayer 22b 0 functions as the above-mentioned second alignment film 22b.
  • the orientation direction of the monolayer 22b 0 is determined as follows. As shown in FIG. 9B, the monolayer 22b 0 can be oriented by draining the cleaning liquid 24. The upward arrow indicates the direction in which the lower structure 100b is pulled up, and the downward arrow indicates the orientation direction.
  • the monomolecular film 22b 0 bonded via the siloxane bond has a photosensitive group
  • the monomolecular film 22b is obtained by passing the unpolarized ultraviolet rays 26 through the polarizing element 25 and the polarized light 26p.
  • the photosensitive group is crosslinked or polymerized.
  • the thick line in FIG. 9D represents a bridge.
  • the monomolecular alignment film 22b 0 becomes a monomolecular alignment film having uniform orientation anisotropy with respect to the liquid crystal display.
  • a monolayer alignment film exhibiting orientation anisotropy can also be obtained.
  • Whether the alignment treatment of the alignment film was performed by draining or irradiation with polarized light or by rubbing can be known by whether or not the alignment film is scratched.
  • the alignment film is not damaged by drainage or irradiation with polarized light.
  • rubbing damages the alignment film.
  • the liquid crystal material 21 composed of rod-shaped molecules is oriented in a specific direction by the single molecule alignment film 22b 0 .
  • the solution 23 containing the silane compound is a solution in which the silane compound is dissolved in a solvent. A part of the silane compound may be in an undissolved state. Typical of such solutions are supersaturated solutions.
  • Y represents one selected from the group consisting of hydrogen, an alkyl group, an alkoxyl group, a fluorine-containing alkyl group, and a fluorine-containing alkoxy group.
  • (6) to (14) specifically exemplify the trichlorosilane-based compound.
  • Compound (12) has a photosensitive cinnamoyl group.
  • Compound (13) and compound (14) also have a photosensitive carconyl group. By irradiating with ultraviolet rays, the photosensitive base is polymerized.
  • an isocyanate-based silane compound in which a chlorosilyl group is replaced with an isocyanate group, or an alkoxy-based silane compound in which a chlorosilyl group can be treated as an alkoxy group may be used.
  • isocyanate-based silane compound (15) or alkoxy-based silane compound (16) can be used instead of chlorosilane (6).
  • isocyanate-based silane compound (15) CH 3 (CH 2 ) 9 Si (OC 2 H 5 ) 3
  • Using an isocyanate-based silane compound or an alkoxy-based silane compound has the advantage that hydrochloric acid is not generated during chemical bonding, so there is no damage to the equipment and work is easy.
  • the following chemical formula (1) shows a reaction step when CF 3- (CF 2 ) 7- (CH 2 ) 2 -SiCl 3 shown in compound (10) is brought into contact with a glass substrate as a silane compound.
  • the first dehydrochlorination reaction represented by the chemical formula (1) is a chemisorption reaction.
  • a silane compound solution is brought into contact with a glass substrate having an OH group, a dehydrochlorination reaction occurs.
  • This reaction is a reaction between a SiCl group and an OH group of a silane compound. If the silane compound solution contains a large amount of water, the reaction with the substrate is hindered. Therefore, in order to allow the reaction to proceed smoothly, it is desirable to use a non-aqueous solvent that does not contain active hydrogen such as an OH group, and it is desirable to carry out the reaction in an atmosphere with low humidity. The details of the humidity conditions will be described later. Then, through H2O hydrolysis and drying / dehydration, a film bonded via a siloxane bond is formed on the surface of the glass substrate.
  • Examples of the solvent for the silane compound that can be used in the present embodiment include at least one selected from the group consisting of a water-free hydrocarbon solvent, a fluorocarbon solvent, and a silicone solvent.
  • Examples of the petroleum-based solvent that can be used in this embodiment include petroleum naphtha, solvent naphtha, petroleum ether, petroleum benzine, isoparaffin, normal paraffin, decalin, industrial gasoline, kerosene, ligroin, dimethylmillicone, phenylsilicone, and alkyl modification. At least one selected from the group consisting of silicones and polyester silicones.
  • fluorocarbon solvent that can be used in this embodiment, at least one selected from the group consisting of a fluorocarbon solvent, fluorinert (product of 3M), and aflude (product of Asahi Glass) can be mentioned. These solvents may be used alone or in combination of two or more compatible with each other.
  • silicone has only a small amount of water and is difficult to absorb moisture. Further, the silicone acts to solvate the chlorosilane compound to prevent the chlorosilane compound from coming into direct contact with water. Therefore, when the solution composed of the chlorosilane compound and the silicone is brought into contact with the base layer, the chlorosilane compound can be chemically adsorbed on the OH group exposed on the base layer while preventing the adverse effect of the moisture in the ambient atmosphere.
  • the optical waveguide 11, the mirrors 30 and 40, the dielectric layer 51, and the partition wall 73 in the optical device 100B can be formed from, for example, the following materials.
  • the material having a refractive index of 2 or more is at least one selected from the group consisting of SiN x , AlN x , TiO x , ZrO x , NbO y , and TaO y .
  • the material having a refractive index of less than 2 is at least one selected from the group consisting of SiO x and AlO x .
  • the material can secure a large number of OH groups, which are adsorption sites of the silane compound. Therefore, an alignment film having excellent alignment characteristics can be formed on the surface of the material.
  • the electrode 62b in the optical device 100B can be formed from at least one conductive material selected from the group consisting of ITO and Al.
  • the sealing member 79 in the optical device 100B may be formed of a polymer material such as acrylic or silicone. In these conductive materials and polymer materials, there are few OH groups which are adsorption sites of the silane compound. Therefore, when an alignment film is also formed on the surface of these materials, the surface is subjected to a hydrophilization treatment to generate or increase OH groups. As this hydrophilization treatment, it is effective to provide a SiO 2 film or a SiN x film on the surface, or to generate an OH group on the surface by UV — O3 treatment.
  • the cleaning method in this embodiment for example, there are immersion and steam cleaning.
  • steam cleaning can strongly remove excess silane compounds that are not chemically adsorbed on the entire surface of the lower structure 100b by the osmotic force of steam.
  • the cleaning solvent that can be used in the present embodiment include at least one selected from the group consisting of a water-free hydrocarbon solvent, a fluorocarbon solvent, and a silicone solvent.
  • the petroleum-based cleaning solvent that can be used in this embodiment include petroleum naphtha, solvent naphtha, petroleum ether, petroleum benzine, isoparaffin, normal paraffin, decalin, industrial gasoline, kerosene, ligroin, dimethylmillicone, phenylsilicone, and alkyl.
  • the fluorocarbon solvent that can be used in this embodiment includes at least one selected from the group consisting of a fluorocarbon solvent, fluorinert (a product of 3M), and aflude (a product of Asahi Glass). These solvents and solvents may be used alone or in combination of two or more compatible with each other.
  • FIG. 9B As an orientation method by draining, as shown in FIG. 9B, there is a method of holding the surface of the lower structure 100b in the vertical direction and draining the cleaning liquid. As a result, the cleaning liquid can be drained only in the vertical direction. In particular, when the cleaning liquid having a boiling point of 200 ° C. or lower is drained, the drying property after draining is excellent. Further, chloroform is excellent in the removability of the chlorosilane polymer produced by the reaction between chlorosilane and water.
  • the cleaning liquid As an orientation method by draining, there is also a method of draining the cleaning liquid by spraying gas on the surface of the lower structure 100b. As a result, the cleaning liquid can be drained in a short time only in the direction in which the gas is blown. In particular, in the case of draining the cleaning liquid having a boiling point of 150 ° C. or higher, the cleaning liquid does not evaporate even if the gas is sprayed. Further, N-methyl-2pyrrolidinone is excellent in the removability of the chlorosilane polymer produced by the reaction between chlorosilane and water.
  • the irradiated polarized ultraviolet light may have a wavelength distribution of, for example, 300 nm or more and 400 nm or less.
  • the irradiation amount is, for example, about 50 mJ / cm 2 or more and about 2000 mJ / cm 2 or less at 365 nm.
  • the orientation of the liquid crystal material tends to be homogenic orientation.
  • the irradiation amount is less than 100 mJ / cm2
  • the orientation of the liquid crystal material tends to be pre-tilt orientation.
  • the deviation in the orientation direction of the liquid crystal material can be known by measuring the retardation of the liquid crystal cell.
  • the liquid crystal material has a phase-advancing axis in which the phase of light advances and a slow-phase axis in which the phase of light is delayed due to optical anisotropy.
  • the deviation in the orientation direction of the liquid crystal material is determined by the angle formed by the direction of the orientation process and the slow axis direction of the liquid crystal material.
  • the orientation direction of the liquid crystal material is from a desired direction. It was off by 0.5 degrees.
  • the deviation in the orientation direction of the liquid crystal material was reduced to 0.1 degrees by the alignment film 22 which is the polyimide alignment film (that is, the rubbing alignment film). This is because the polyimide alignment film has a higher orientation control force than the single molecule alignment film.
  • the deviation in the orientation direction of the liquid crystal material is reduced to 0.05 degrees by the first alignment film 22a which is a polyimide alignment film and the second alignment film 22b which is a photoalignment film. It was confirmed that the alignment direction of the liquid crystal material 21 can be more uniformly aligned by adding the optical alignment film in addition to the polyimide alignment film.
  • FIG. 10A is a diagram schematically showing how light is emitted from the optical device 100A according to the first embodiment.
  • FIG. 10B is a diagram schematically showing how light is emitted from the optical device 100B according to the second embodiment.
  • the loss of emitted light is about 50%.
  • the loss of emitted light was reduced to about 25%.
  • the loss of emitted light was about 25%.
  • Polyimide alignment film is often used for liquid crystal displays. In a liquid crystal display, light passes through the alignment films of the upper and lower substrates only once. Therefore, even if the polyimide alignment film is thick and the thickness is not uniform, the light loss due to absorption and scattering in the alignment film is not so problematic in one transmission.
  • the light waveguide region 20 is reflected multiple times by the reflecting surface 30s of the mirror 30 and the reflecting surface 40s of the mirror 40. Propagate. Therefore, in the configuration in which the polyimide alignment film is provided on both sides, the light loss due to absorption and scattering in the alignment film cannot be ignored.
  • a polyimide alignment film is provided on the reflective surface 30s of the mirror 30, and a polyimide alignment film is provided on the upper surface of the lower structure 100b. No structure is adopted.
  • the light loss can be reduced to about half.
  • the second alignment film 22b which is a light alignment film, makes the orientation direction of the liquid crystal material 21 more uniform without substantially causing light loss in the second alignment film 22b. Can be done.
  • a plurality of optical waveguide regions 20 arranged in the Y direction are provided.
  • Such an optical waveguide region 20 may be, for example, one 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 the optical device 110 according to the present modification when viewed from the Z direction. However, in FIG. 11A, the illustration of the second alignment film 22b is omitted.
  • FIG. 11B is a diagram showing a state in which the superstructure 100a is removed from the structure shown in FIG. 11A.
  • 12A, 12B, and 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 superstructure 110a in this modification has the same structure as the superstructure 100a in the second embodiment.
  • the lower structure 110b in the present modification unlike the lower structure 100b in the second embodiment, as shown in FIG. 11B, two partition walls 73 are arranged on both sides of one optical waveguide region 20. Has been done.
  • the lower structure 100b has a relatively wide recess. With such a structure, the reflecting surface 40s of the mirror 40 is exposed over a relatively wide range extending along the X and Y directions. As shown in FIG. 12C, the recess is located between two protrusions extending in the X direction.
  • a planar optical waveguide is formed by the reflecting surface 30s of the mirror 30, the reflecting surface 40s of the mirror 40, and one optical waveguide region 20 extending along the X and Y directions located between the two. ..
  • the optical waveguide region 20 is surrounded by a reflecting surface 30s of the mirror 30, a reflecting surface 40s of the mirror 40, and two convex portions formed by the partition wall 73.
  • the optical waveguide region 20 is filled with a dielectric member 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.
  • the 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 an optical beam.
  • the light beam formed in the optical waveguide region 20 is emitted to the outside through the mirror 30, the electrode 62a, and the substrate 50a. Even in the optical device 110 according to the modification, the X-direction component and the Y-direction component of the wave vector of the emitted light can be changed.
  • the second alignment film 22b is formed by rubbing due to the influence of the stepped portion on the edge of the recess, good alignment performance cannot be realized especially in the stepped portion.
  • the second alignment film 22b is formed by a method that does not depend on rubbing, for example, irradiation with polarized light. This makes it possible to form the second alignment film 22b having good alignment performance even in the stepped portion.
  • the optical waveguide 10 is a slow light waveguide.
  • the optical waveguide 10 does not have to be a slow light waveguide.
  • the optical waveguide 10 may be, for example, an optical waveguide that does not include the mirror 30 and the mirror 40 and propagates light within the optical waveguide region 20 by total internal reflection on the surface of the substrate 50a and the surface of the substrate 50b.
  • the light propagating through the optical waveguide may be emitted to the outside not through the substrate 50a or the substrate 50b, for example, from the end of the optical waveguide 10.
  • the alignment films 22, 22a, and 22b are functional films that orient the liquid crystal material contained in the dielectric member 21 in a specific direction.
  • Various functional films may be provided in place of or in addition to these alignment films, depending on other purposes or uses.
  • a functional film having at least one of properties such as heat resistance, scratch resistance, adhesiveness, translucency, light shielding property, flexibility, rigidity, conductivity, and insulating property may be provided.
  • the dielectric member 21 is not limited to the liquid crystal material, and may include a material suitable for the performance of the functional film.
  • FIG. 13 is a diagram showing a configuration example of an optical scan device 100 in which elements such as an optical turnout 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).
  • the optical scan device 100 also includes embodiments 1 and 2, as well as an optical device according to a modification.
  • the light source 130 can be, for example, a light emitting element such as a semiconductor laser.
  • the light source 130 in this example emits light of a single wavelength having a wavelength of ⁇ in free space.
  • the optical turnout 90 branches the light from the light source 130 and introduces it into the waveguide in the 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.
  • a control signal is sent from each of the plurality of electrodes 62B to the plurality of phase shifters 80 in the phase shifter array 80A.
  • 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 scan device 100.
  • all the components shown in FIG. 13 can be integrated on a chip having a size of about 2 mm ⁇ 1 mm.
  • FIG. 14 is a schematic diagram showing a state in which a light beam such as a laser is irradiated far from the optical scan device 100 to perform a two-dimensional scan.
  • the two-dimensional scan is performed by moving the beam spot 310 horizontally and vertically.
  • a known TOF (Time Of Flight) method a two-dimensional distance measurement image can be acquired.
  • the TOF method is a method of calculating the flight time of light by irradiating a laser and observing the reflected light from an object to obtain a distance.
  • FIG. 15 is a block diagram showing a configuration example of a LiDAR system 300, which is an example of a photodetection system capable of generating such a ranging image.
  • the LiDAR system 300 includes an optical scan device 100, a photodetector 400, a signal processing circuit 600, and a control circuit 500.
  • the photodetector 400 detects the light emitted from the optical scan device 100 and reflected from the object.
  • the photodetector 400 can be, for example, an image sensor sensitive to the wavelength ⁇ of light emitted from the optical scan device 100, or a photodetector including a light receiving element such as a photodiode.
  • the photodetector 400 outputs an electric signal according to the amount of received light.
  • the signal processing circuit 600 calculates the distance to the object based on the electric signal output from the photodetector 400, and generates the distance distribution data.
  • the distance distribution data is data showing a two-dimensional distribution of distance (that is, a distance measurement image).
  • the control circuit 500 is a processor that controls the optical scan device 100, the photodetector 400, and the signal processing circuit 600.
  • the control circuit 500 controls the timing of irradiation of the light beam from the optical scan 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 a 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. Further, considering the application to an in-vehicle system, the higher the frame rate, the higher the frequency of acquiring the distance measurement image, and the more accurately the obstacle can be detected. For example, when traveling at 60 km / h, an image can be acquired every time the car moves about 28 cm at a frame rate of 60 fps. At a frame rate of 120 fps, an image can be acquired every time the car moves about 14 cm. At a frame rate of 180 fps, an image can be acquired every time the car moves about 9.3 cm.
  • the time required to acquire one ranging image depends on the speed of the beam scan. For example, in order to acquire an image having a resolution of 100 ⁇ 100 at 60 fps, it is necessary to perform a beam scan at 1.67 ⁇ s or less for each point.
  • the control circuit 500 controls the emission of the light beam by the optical scan device 100 and the signal storage / reading by the photodetector 400 at an operating speed of 600 kHz.
  • the optical scanning device or the optical device in each of the above-described embodiments of the present disclosure has almost the same configuration and can also be used as an optical receiving device.
  • the optical receiving device includes the same waveguide array 10A as the optical scanning device, and a first adjusting element that adjusts the direction of receivable light.
  • Each of the first mirrors 30 of the waveguide array 10A transmits light incident on the opposite side of the first reflecting surface from the third direction.
  • Each optical waveguide layer 20 of the waveguide array 10A propagates the light transmitted through the first mirror 30 in the second direction.
  • Receivable light captured in each optical waveguide layer 20 by the first adjusting element changing at least one of the refractive index and thickness of the optical waveguide layer 20 in each waveguide element 10 and the wavelength of light. You can change the direction. Further, the light output from the optical receiving device through the same plurality of phase shifters 80, 80a and 80b as the optical scanning device and the plurality of phase shifters 80, 80a and 80b from the plurality of waveguide elements 10.
  • the second adjusting element for changing the phase difference between the two is provided, the direction of the receivable light can be changed two-dimensionally.
  • an optical receiving device 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 turnout 90 through the phase shifter array 80A, and finally collected at one place and sent to the receiving circuit.
  • the intensity of the light collected in that one place represents the sensitivity of the optical receiving device.
  • the sensitivity of the optical receiving device can be adjusted by the adjusting elements separately incorporated in the waveguide array and the phase shifter array 80A.
  • the directions of the wave vector are opposite to each other.
  • the incident light has an optical component in the direction in which the waveguide element 10 extends (X direction in the figure) and an optical component in the arrangement direction of the waveguide elements 10 (Y direction in the figure).
  • the sensitivity of the optical component in the X direction can be adjusted by the adjusting element incorporated in the waveguide array 10A.
  • the sensitivity of the optical component in the arrangement direction of the waveguide element 10 can be adjusted by the adjusting element incorporated in the phase shifter array 80A. From the phase difference ⁇ of the light when the sensitivity of the optical receiving device is maximized, the refractive index nw and the thickness d of the optical waveguide layer 20, ⁇ and ⁇ 0 shown in FIG. 4 can be found. Thereby, the incident direction of the light can be specified.
  • the optical scanning device and the optical receiving device in the embodiment of the present disclosure can be used for applications such as a rider system mounted on a vehicle such as an automobile, a UAV, or an AGV.

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