Optical devices, photodetection systems, and optical fibers

Abstract

This optical device comprises: a first substrate (100a) having a first surface spreading in a first direction and a second direction that intersects with the first direction; a second substrate (100b) having a second surface facing the first surface; a film (22) binding to the first surface and / or second surface via a siloxane bond; and at least one optical waveguide layer (20) that is positioned between the first substrate and the second substrate and includes a dielectric member (21) contacting the film.

Description

[Technical Field]

[0001] This disclosure relates to optical device photodetection systems and optical fibers. [Background technology]

[0002] Conventionally, various devices capable of scanning space using light have been proposed.

[0003] Patent Document 1 discloses a configuration that enables optical scanning using a drive device that rotates a mirror.

[0004] Patent Document 2 discloses an optical phased array having a plurality of nanophotonic antenna elements arranged in two dimensions. Each antenna element is optically coupled to a variable optical delay line (i.e., 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 the phase shifter. This makes it possible to change the amplitude distribution of the far-field emission pattern.

[0005] Patent Document 3 discloses an optical deflection element comprising an optical waveguide having an optical waveguide layer through which light is guided, and a first distributed Bragg reflector formed on the upper and lower surfaces of the optical waveguide layer, an optical inlet for injecting light into the waveguide, and an optical outlet formed on the surface of the waveguide for emitting light that has been injected from the optical inlet and guided through the waveguide. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2013 / 168266 [Patent Document 2] Special Publication No. 2016-508235 [Patent Document 3] Japanese Patent Publication No. 2013-16591 [Patent Document 4] Japanese Patent Laid-Open No. 2001-100214

Summary of the Invention

Problems to be Solved by the Invention

[0007] One aspect of the present disclosure provides a novel optical device that can realize optical scanning with low optical loss and a relatively simple configuration.

Means for Solving the Problems

[0008] An optical device according to one aspect of the present disclosure includes a first substrate having a first surface extending in a first direction and a second direction intersecting the first direction, a second substrate having a second surface facing the first surface, and a film bonded via a xan bond to the first surface and / or the second surface, and at least one optical waveguide layer located between the first substrate and the second substrate, the at least one optical waveguide layer including a dielectric member in contact with the film. An encompassing or specific aspect of the present disclosure may be implemented by a device, a system, a method, or any combination thereof. Shiro

Effects of the Invention

[0009] According to one aspect of the present disclosure, a one-dimensional or two-dimensional optical scan with low optical loss can be realized with a relatively simple configuration.

Brief Description of the Drawings

[0010] [Figure 1] FIG. 1 is a perspective view schematically showing the configuration of an optical scanning device. [Figure 2] FIG. 2 is a diagram schematically showing the cross-sectional structure of one waveguide element and an example of light propagating therethrough. [Figure 3A] 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. [Figure 3B] 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 surface of the waveguide array. [Figure 4] Figure 4 is a schematic perspective view showing a waveguide array in three-dimensional space. [Figure 5] Figure 5 is a schematic diagram of the waveguide array 10A and the phase shifter array 80A as viewed from the normal direction (Z direction) of the light emission surface. [Figure 6A] Figure 6A is a schematic diagram showing an example of an optical device in Embodiment 1 of this disclosure, as viewed from the Z direction. [Figure 6B] Figure 6B is a diagram of Figure 6A with the superstructure omitted. [Figure 7A] Figure 7A is a cross-sectional view taken along the line VIIA-VIIA in Figure 6A. [Figure 7B] Figure 7B is a cross-sectional view taken along the line VIIB-VIIB in Figure 6A. [Figure 7C] Figure 7C is a cross-sectional view taken along the VIIC-VIIC line in Figure 6A. [Figure 8A] Figure 8A is a diagram illustrating the film in Embodiment 1. [Figure 8B] Figure 8B is a diagram illustrating the film in Embodiment 1. [Figure 8C] Figure 8C is a diagram illustrating the film in Embodiment 1. [Figure 8D] Figure 8D is a diagram illustrating the film in Embodiment 1. [Figure 8E] Figure 8E is a diagram illustrating the film in Embodiment 1. [Figure 9] Figure 9 is a schematic diagram illustrating the emission of light from an optical device. [Figure 10] Figure 10 shows an example of the configuration of an optical scanning device in which elements such as optical splitters, waveguide arrays, phase shifter arrays, and light sources are integrated on a circuit board. [Figure 11] Figure 11 is a schematic diagram showing how a 2D scan is performed by irradiating a distant object with a light beam, such as a laser, from an optical scanning device. [Figure 12] Figure 12 is a block diagram showing an example configuration of a LiDAR system capable of generating ranging images. [Figure 13] Figure 13 is a schematic diagram showing an example of an optical fiber in Embodiment 2 of this disclosure. [Modes for carrying out the invention]

[0011] Before describing embodiments of this disclosure, we will explain the knowledge that forms the basis of this disclosure.

[0012] The inventors of the present invention have found that conventional optical scanning devices have the problem of being unable to scan space with light without complicating the device configuration.

[0013] For example, the technology disclosed in Patent Document 1 requires a drive device to rotate the mirror. This results in a complex device configuration and a lack of robustness against vibration.

[0014] In the optical phased array described in Patent Document 2, it is necessary to branch the light and introduce it into multiple column waveguides and multiple row waveguides, and guide the light to multiple antenna elements arranged in two dimensions. As a result, the wiring of the waveguides for guiding the light becomes very complex. Furthermore, the range of the two-dimensional scan cannot be increased. In addition, in order to change the amplitude distribution of the emitted light in the far field of view in two dimensions, it is necessary to connect a phase shifter to each of the multiple antenna elements arranged in two dimensions and attach wiring for phase control to the phase shifter. This changes the phase of the light incident on each of the multiple antenna elements arranged in two dimensions by a different amount. As a result, the configuration of the elements becomes very complex.

[0015] The inventors focused on the above-mentioned problems in the prior art and considered configurations to solve these problems. The inventors found that the above problems can be solved by using a waveguide element having a pair of opposing mirrors and an optical waveguide layer sandwiched between those mirrors. One of the pair of mirrors in the waveguide element has a higher light transmittance than the other, causing a portion of the light propagating through the optical waveguide layer to be emitted 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 will be 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 enables one-dimensional scanning.

[0016] Furthermore, by using an array of multiple waveguide elements, two-dimensional scanning can also be achieved. More specifically, by applying an appropriate phase difference to the light supplied to the multiple waveguide elements and adjusting this phase difference, the direction in which the light emitted from the multiple waveguide elements reinforces each other can be changed. The change in phase difference changes the component of the wave vector of the emitted light that intersects the direction along the longitudinal direction of the optical waveguide layer. This enables two-dimensional scanning. It should be noted that even when performing two-dimensional scanning, it is not necessary to change the refractive index, thickness, or wavelength of the multiple optical waveguide layers by different amounts. That is, two-dimensional scanning can be performed by applying an appropriate phase difference to the light supplied to the multiple optical waveguide layers and synchronously changing at least one of the refractive index, thickness, and wavelength of the multiple optical waveguide layers by the same amount. Thus, according to the embodiments of this disclosure, two-dimensional scanning using light can be achieved with a relatively simple configuration.

[0017] In this specification, “refractive index, thickness, and wavelength” means at least one selected from the group consisting of the refractive index of the optical waveguide, the thickness of the optical waveguide, and the wavelength input to the optical waveguide. To change the direction of light emission, one of the refractive index, thickness, and wavelength may be controlled individually. Alternatively, any two or all of these three may be controlled to change the direction of light emission. In each of the following embodiments, the wavelength of light input to the optical waveguide may be controlled instead of, or in addition to, controlling the refractive index or thickness.

[0018] The basic principles described above can be applied not only to applications that emit light, but also to applications that receive optical signals. By changing at least one of the refractive index, thickness, and wavelength, the direction of the received light can be changed in one dimension. Furthermore, by changing the phase difference of the light using multiple phase shifters connected to multiple waveguide elements arranged in one direction, the direction of the received light can be changed in two dimensions.

[0019] The optical scanning devices and optical receiving devices according to embodiments of this disclosure can be used, for example, as antennas in optical detection systems such as LiDAR (Light Detection and Ranging) systems. Compared to radar systems that use radio waves such as millimeter waves, LiDAR systems use short-wavelength electromagnetic waves (visible light, infrared, or ultraviolet light), and can therefore detect the distance distribution of objects with high resolution. Such LiDAR systems can be mounted on mobile vehicles such as automobiles, UAVs (Unmanned Aerial Vehicles, so-called drones), and AGVs (Automated Guided Vehicles) and used as one of the collision avoidance technologies. In this specification, optical scanning devices and optical receiving devices may be collectively referred to as "optical devices." Devices used in optical scanning devices or optical receiving devices may also be referred to as "optical devices."

[0020] <Example configuration of an optical scanning device> The following describes the configuration of an optical scanning device that performs two-dimensional scanning as an example. However, unnecessarily detailed explanations may be omitted. For example, detailed explanations of already well-known matters and redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding by those skilled in the art. The inventors provide the accompanying drawings and the following description so that those skilled in the art can fully understand this disclosure, and not to limit the subject matter described in the claims. In the following description, identical or similar components are denoted by the same reference numerals.

[0021] In this disclosure, "light" means electromagnetic waves including not only visible light (wavelengths of approximately 400 nm to 700 nm) but also ultraviolet light (wavelengths of approximately 10 nm to 400 nm) and infrared light (wavelengths of approximately 700 nm to 1 mm). In this specification, ultraviolet light may be referred to as "ultraviolet light" and infrared light as "infrared light".

[0022] In this disclosure, “scanning” with light means changing the direction of light. “One-dimensional scanning” means changing the direction of light linearly along a direction intersecting that direction. “Two-dimensional scanning” means changing the direction of light two-dimensionally along a plane intersecting that direction.

[0023] Figure 1 is a schematic perspective view showing the configuration of the optical scanning device 100. The optical scanning device 100 comprises a waveguide array including a plurality of waveguide elements 10. Each of the plurality of waveguide elements 10 has a shape that extends in a first direction (the X direction in Figure 1). The plurality of waveguide elements 10 are regularly arranged in a second direction (the Y direction in Figure 1) that intersects the first direction. The plurality of waveguide elements 10 propagate light in the first direction and emit light in a third direction D3 that intersects a virtual plane parallel to the first and second directions. In this embodiment, the first direction (X direction) and the second direction (Y direction) are orthogonal, but they do not have to be orthogonal. In this embodiment, the 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.

[0024] The orientation of the structures shown in the drawings of this application is set for the sake of clarity of explanation and does not in any way limit the orientation when the embodiments of this disclosure are actually implemented. Furthermore, the shape and size of the whole or part of the structures shown in the drawings do not limit the actual shape and size.

[0025] Each of the plurality of waveguide elements 10 has a first mirror 30 and a second mirror 40 (hereinafter, each may be simply referred to as "mirror") facing each other, and an optical waveguide layer 20 located between the mirrors 30 and 40. Each of the mirrors 30 and 40 has a reflective surface at its interface with the optical waveguide layer 20 that intersects the third direction D3. The mirrors 30 and 40, as well as the optical waveguide layer 20, have a shape that extends in the first direction (X direction).

[0026] As will be described later, the multiple first mirrors 30 of the multiple waveguide elements 10 may be multiple parts of a single mirror. Similarly, the multiple second mirrors 40 of the multiple waveguide elements 10 may be multiple parts of a single mirror. Furthermore, the multiple optical waveguide layers 20 of the multiple waveguide elements 10 may be multiple parts of a single optical waveguide layer. At a minimum, multiple waveguides can be formed by (1) each first mirror 30 being configured separately from other first mirrors 30, (2) each second mirror 40 being configured separately from other second mirrors 40, or (3) each optical waveguide layer 20 being configured separately from other optical waveguide layers 20. "Configured separately" includes not only physically creating a space between them, but also separating them by inserting materials with different refractive indices in between.

[0027] The reflective surfaces of the first mirror 30 and the second mirror 40 are positioned approximately parallel to each other. Of the two mirrors 30 and 40, at least the first mirror 30 has the property of transmitting a portion of the light propagating through the optical waveguide layer 20. In other words, the first mirror 30 has a higher light transmittance than the second mirror 40 with respect to that light. Therefore, a portion 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 may be multilayer mirrors formed by, for example, a dielectric multilayer film (sometimes referred to as a "multilayer reflective film").

[0028] By controlling the phase of the light input to each waveguide element 10, and further by synchronously and simultaneously changing 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, two-dimensional scanning using light can be realized.

[0029] The inventors analyzed the operating principle of the waveguide element 10 in order to realize such a two-dimensional scan. Based on the results, they succeeded in realizing a two-dimensional scan using light by synchronously driving multiple waveguide elements 10.

[0030] As shown in Figure 1, 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 opposite the reflective surface of the first mirror 30. The direction D3 of the emitted light depends on the refractive index, thickness, and wavelength of the optical waveguide layer. In this embodiment, at least one of the refractive index, thickness, and wavelength of each optical waveguide layer is controlled synchronously so that the light emitted from each waveguide element 10 is in approximately the same direction. This makes it possible to change the X component of the wave vector of the light emitted from multiple waveguide elements 10. In other words, the direction D3 of the emitted light can be changed along the direction 101 shown in Figure 1.

[0031] Furthermore, since the light emitted from multiple waveguide elements 10 is directed in the same direction, the emitted light interferes with each other. By controlling the phase of the light emitted from each waveguide element 10, the direction in which the light reinforces due to interference can be changed. For example, if multiple waveguide elements 10 of the same size are arranged at equal intervals in the Y direction, a certain amount of light with different phases is input to each waveguide element 10. By changing this phase difference, the Y-direction component of the wave vector of the emitted light can be changed. In other words, by changing the phase difference of the light introduced into each of the multiple waveguide elements 10, the direction D3 in which the emitted light reinforces due to interference can be changed along the direction 102 shown in Figure 1. This makes it possible to realize two-dimensional scanning using light.

[0032] The operating principle of the optical scanning device 100 is described below.

[0033] <Operating principle of waveguide elements> Figure 2 schematically shows the cross-sectional structure of a waveguide element 10 and an example of propagating light. In Figure 2, the direction perpendicular to the X and Y directions shown in Figure 1 is defined as the Z direction, and a cross-section parallel to the XZ plane of the waveguide element 10 is schematically shown. In the waveguide element 10, a first mirror 30 and a second mirror 40 are arranged so as to sandwich the optical waveguide layer 20. The first reflective surface 30s of the first mirror 30 and the second reflective surface 40s of the second mirror 40 are opposite each other. In this specification, the "first reflective surface 30s" may be simply referred to as the "reflective surface 30s," and the "second reflective surface 40s" may be simply referred to as the "reflective surface 40s." Light 20L introduced from one end of the optical waveguide layer 20 in the X direction propagates through the optical waveguide layer 20, repeatedly reflected by the first reflective surface 30s of the first mirror 30 located on the upper surface (upper surface in Figure 2) and the second reflective surface 40s of the second mirror 40 located on the lower surface (lower surface in Figure 2). The light transmittance of the first mirror 30 is higher than that of the second mirror 40. Therefore, a portion of the light can be output mainly from the first mirror 30.

[0034] In conventional waveguides such as optical fibers, light propagates along the waveguide while undergoing repeated total internal reflection. In contrast, in the waveguide element 10 of this embodiment, light propagates while being repeatedly reflected by mirrors 30 and 40 positioned above and below the optical waveguide layer 20. Therefore, there are no constraints on the propagation angle of light. Here, the propagation angle of light refers to the angle of incidence to the interface between the mirror 30 or mirror 40 and the optical waveguide layer 20. Light incident at an angle closer to perpendicular to the mirror 30 or mirror 40 can also propagate. That is, light incident at an angle smaller than the critical angle for total internal reflection can also propagate. Therefore, the group velocity of light in the direction of propagation is significantly lower than the speed of light in free space. As a result, the waveguide element 10 has the property that the propagation conditions of light 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. Such a waveguide is called a "reflective waveguide" or "slow-light waveguide".

[0035] The emission angle θ of light emitted from the waveguide element 10 into the air is expressed by the following equation (1).

number

[0036] As can be seen from equation (1), the wavelength of light in air is λ, and the refractive index of the optical waveguide layer 20 is n. w The direction of light emission can be changed by changing either the thickness d of the optical waveguide layer 20 or the thickness d of the optical waveguide layer 20.

[0037] For example, n w When =2, d=387nm, λ=1550nm, and m=1, the emission angle is 0°. From this state, the refractive index is n w When the refractive index is changed to 2.2, the emission angle changes to approximately 66°. On the other hand, when the thickness is changed to d=420nm without changing the refractive index, the emission angle changes to approximately 51°. When the wavelength is changed to λ=1500nm without changing either the refractive index or the thickness, the emission angle changes to approximately 30°. Thus, the wavelength of light λ and the refractive index n of the optical waveguide layer 20 are... w By changing either the thickness d of the optical waveguide layer 20, the direction of light emission can be significantly altered.

[0038] Therefore, the optical scanning device 100 in the embodiments of this disclosure controls the direction of light emission by controlling at least one of the wavelength λ of light input to the optical waveguide layer 20, the refractive index nw of the optical waveguide layer 20, and the thickness d of the optical waveguide layer 20. The wavelength λ of light may be kept constant during operation. In that case, light scanning can be achieved with a simpler configuration. The wavelength λ is not particularly limited. For example, the wavelength λ may be in the wavelength range of 400 nm to 1100 nm (visible light to near-infrared light) in which high detection sensitivity can be obtained in photodetectors or image sensors that detect light by absorbing it with common silicon (Si). In other examples, the wavelength λ may be in the near-infrared wavelength range of 1260 nm to 1625 nm, in which transmission loss is relatively small in optical fibers or Si waveguides. Note that these wavelength ranges are examples. The wavelength range of light used is not limited to the visible light or infrared light wavelength range, but may be, for example, the ultraviolet light wavelength range.

[0039] To change the direction of the emitted light, the optical scanning device 100 may include a first adjustment element that changes at least one of the refractive index, thickness, and wavelength of the optical waveguide layer 20 in each waveguide element 10.

[0040] As described above, by using the waveguide element 10, the refractive index n of the optical waveguide layer 20 w By changing at least one of the thickness d and wavelength λ, the direction of light emission can be significantly altered. This allows the emission angle of light emitted from the mirror 30 to be changed along the waveguide element 10. Such a one-dimensional scan can be achieved by using at least one waveguide element 10.

[0041] To adjust the refractive index of at least a portion of the optical waveguide layer 20, the optical waveguide layer 20 may contain a liquid crystal material or an electro-optic material. The optical waveguide layer 20 may be sandwiched between a pair of electrodes. By applying a voltage to the pair of electrodes, the refractive index of the optical waveguide layer 20 can be changed.

[0042] To adjust the thickness of the optical waveguide layer 20, for example, at least one actuator may be connected to at least one of the first mirror 30 and the second mirror 40. By changing the distance between the first mirror 30 and the second mirror 40 using at least one actuator, the thickness of the optical waveguide layer 20 can be changed. If the optical waveguide layer 20 is formed from a liquid, the thickness of the optical waveguide layer 20 can be easily changed.

[0043] <Operating principle of 2D scanning> In a waveguide array in which multiple waveguide elements 10 are arranged in one direction, the direction of light emission changes due to the interference of light emitted from each waveguide element 10. The direction of light emission can be changed by adjusting the phase of the light supplied to each waveguide element 10. The principle is explained below.

[0044] Figure 3A shows a cross-section of a waveguide array that emits light in a direction perpendicular to the emission surface of the waveguide array. Figure 3A also shows the phase shift amount of light propagating through each waveguide element 10. Here, the phase shift amount is a value based on the phase of the light propagating through the leftmost waveguide element 10. The waveguide array in this embodiment includes a plurality of waveguide elements 10 arranged at equal intervals. In Figure 3A, the dashed arcs indicate the wavefront of the light emitted from each waveguide element 10. The straight lines indicate the wavefront formed by the interference of light. The arrows indicate the direction of the light emitted from the waveguide array (i.e., the direction of the wave vector). In the example of Figure 3A, the phase of the light propagating through the optical waveguide layer 20 in each waveguide element 10 is the same. In this case, the light is emitted in a direction (Z direction) perpendicular to both the arrangement direction of the waveguide elements 10 (Y direction) and the direction in which the optical waveguide layer 20 extends (X direction).

[0045] Figure 3B shows a cross-section of a waveguide array in which light is emitted in a direction different from the direction perpendicular to the emission surface of the waveguide array. In the example shown in Figure 3B, the phase of the light propagating through the optical waveguide layer 20 in multiple waveguide elements 10 differs by a certain amount (Δφ) in the array direction. In this case, the light is emitted in a direction different from the Z direction. By changing this Δφ, the Y-direction component of the wave vector of the light can be changed. If the distance between the centers of two adjacent waveguide elements 10 is p, the emission angle α0 of the light is expressed by the following equation (2).

number

[0046] In the example shown in Figure 2, the direction of light emission is parallel to the XZ plane; that is, α0 = 0°. In the examples shown in Figures 3A and 3B, the direction of light emitted from the optical scanning device 100 is parallel to the YZ plane; that is, θ = 0°. However, generally, the direction of light emitted from the optical scanning device 100 is not parallel to either the XZ plane or the YZ plane; that is, θ ≠ 0° and α0 ≠ 0°.

[0047] Figure 4 is a schematic perspective view of a waveguide array in three-dimensional space. The thick arrows in Figure 4 represent the direction of light emitted from the optical scanning device 100. θ is the angle between the direction of light emission and the YZ plane. θ satisfies equation (1). α0 is the angle between the direction of light emission and the XZ plane. α0 satisfies equation (2).

[0048] <Phase control of light introduced into waveguide arrays> To control the phase of light emitted from each waveguide element 10, for example, a phase shifter that changes the phase of light may be provided before introducing light into the waveguide element 10. The optical scanning device 100 in this embodiment comprises a plurality of phase shifters connected to each of the plurality of waveguide elements 10, and a second adjustment element that adjusts the phase of light propagating through each phase shifter. Each phase shifter includes a waveguide that is connected directly to the optical waveguide layer 20 in one of the plurality of waveguide elements 10 or via another waveguide. The second adjustment element changes the direction of light emitted from the plurality of waveguide elements 10 (i.e., the third direction D3) by changing the phase difference of the light propagating from the plurality of phase shifters to the plurality of waveguide elements 10. In the following description, a plurality of arranged phase shifters may be referred to as a "phase shifter array," similar to a waveguide array.

[0049] Figure 5 is a schematic diagram of the waveguide array 10A and the phase shifter array 80A as viewed from the normal direction (Z direction) of the light output surface. In the example shown in Figure 5, 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 be the same length or may have different lengths. If each phase shifter 80 is the same length, for example, the amount of phase shift can be adjusted by the drive voltage. Alternatively, by creating a structure in which the length of each phase shifter 80 is varied in equal steps, an equal step phase shift can be provided with the same drive voltage. Furthermore, this optical scanning device 100 further includes an optical splitter 90 that splits and supplies light to multiple phase shifters 80, a first drive circuit 110 that drives each waveguide element 10, and a second drive circuit 120 that drives each phase shifter 80. The straight arrows in Figure 5 indicate the input of light. Two-dimensional scanning can be achieved by independently controlling the separately provided first drive circuit 110 and second drive circuit 120. In this example, the first drive circuit 110 functions as one element of the first adjustment element, and the second drive circuit 120 functions as one element of the second adjustment element.

[0050] The first drive circuit 110 changes the angle of light emitted from the optical waveguide layer 20 by changing at least one of the refractive index and thickness of the optical waveguide layer 20 in each waveguide element 10. The second drive circuit 120 controls the waveguide in each phase shifter 80 Road By changing the refractive index, a waveguide can be created. Road The phase of light propagating inside is changed. The optical splitter 90 may be composed of a waveguide through which light propagates by total internal reflection, or it may be composed of a reflective waveguide similar to the waveguide element 10.

[0051] Alternatively, the phase of each beam of light branched by the optical splitter 90 may be controlled before introducing each beam of light into the phase shifter 80. For this phase control, a passive phase control structure can be used, for example, by adjusting the length of the waveguide leading to the phase shifter 80. Alternatively, a phase shifter controllable by an electrical signal having a similar function to the phase shifter 80 may be used. In this way, for example, the phase may be adjusted before being introduced into the phase shifter 80 so that all phase shifters 80 are supplied with light of equal phase. Such adjustment simplifies the control of each phase shifter 80 by the second drive circuit 120.

[0052] An optical device having a configuration similar to the optical scanning device 100 described above can also be used as an optical receiving device. Details of the operating principle and operating method of the optical device are disclosed in U.S. Patent Application Publication No. 2018 / 0224709. The entire disclosure of this document is incorporated herein by reference.

[0053] <Liquid crystal alignment film> When the optical waveguide layer 20 contains a liquid crystal material, an alignment film, for example, made of polyimide, may be provided on the reflective surface 30s of the mirror 30 and / or the reflective surface 40s of the mirror 40 to align the liquid crystal material. The polyimide alignment film is thick and non-uniform. The thickness of the polyimide alignment film is about 80 nm, and the thickness variation is between 0 nm and 150 nm. When light is incident on the thick and non-uniform polyimide alignment film, absorption and scattering of light occur. Therefore, as shown in Figure 2, when light undergoes multiple reflections and propagates along the X direction in the optical waveguide layer 20, the light is absorbed and scattered many times by the polyimide alignment film. As a result, significant optical loss can occur in the optical waveguide layer 20. According to the inventors' research, this optical loss is about 50%.

[0054] Furthermore, during the fabrication process of the optical device 100, when the polyimide alignment film is applied to the reflective surface 30s of the mirror 30 and / or the reflective surface 40s of the mirror 40, the polyimide alignment film may also be applied to the electrodes for applying voltage to the optical waveguide layer 20. The polyimide alignment film can function as an insulating film. Therefore, the polyimide alignment film applied to the electrodes is removed. Alternatively, by masking, the polyimide alignment film is applied only to the reflective surface 30s and / or the reflective surface 40s of the mirror 40. As a result, the number of steps in the fabrication of the optical device may increase.

[0055] Based on the above considerations, the inventors have conceived of the optical device described in the following section. In the optical device of this disclosure, a film bonded via siloxane bonds between Si and O (see, for example, Patent Document 4) is provided on at least one of the first surface of the first substrate and the second surface of the second substrate, in which the optical waveguide layer is located, instead of a polyimide-oriented film. This film can suppress optical loss in the optical waveguide layer. Furthermore, the film provided on the electrodes does not function as an insulating film. Therefore, it is not necessary to remove the film provided on parts other than the first surface and / or the second surface, or to provide the film only on the first surface and / or the second surface by masking. Thus, the fabrication of the optical device becomes easier.

[0056] The optical device relating to the first item includes a first substrate having a first surface extending in a first direction and a second direction intersecting the first direction, a second substrate having a second surface facing the first surface, and the first surface and / or the second surface Shiro The device comprises a film bonded via xane bonds, and at least one optical waveguide layer located between the first substrate and the second substrate, the optical waveguide layer including a dielectric member in contact with the film.

[0057] This optical device enables optical scanning with a relatively simple configuration and low optical loss.

[0058] The optical device relating to the second item further comprises, in the optical device relating to the first item, at least one optical waveguide connected to the optical waveguide layer.

[0059] This optical device can supply light to the optical waveguide layer from at least one optical waveguide.

[0060] The optical device relating to the third item is the optical device relating to the second item, wherein the leading edge of the optical waveguide is located between the first substrate and the second substrate. The optical waveguide includes a first grating at its leading edge.

[0061] In this optical device, light propagating through the optical waveguide can be efficiently coupled to the optical waveguide layer via the first grating.

[0062] The optical device relating to the fourth item is an optical device relating to the second or third item, wherein the optical waveguide has a portion that does not overlap with either the first substrate or the second substrate when viewed from a direction perpendicular to the first surface. The optical waveguide has a second grating in the portion that does not overlap.

[0063] This optical device allows external light to be efficiently coupled to the optical waveguide via a second grating.

[0064] The optical device relating to item 5 is an optical device relating to any of items 1 to 4, wherein each of the first substrate and the second substrate includes a mirror. The mirror on the first substrate has the first surface. The mirror on the second substrate has the second surface.

[0065] In this optical device, light can propagate through the optical waveguide layer while being reflected by the first surface of the mirror on the first substrate and the second surface of the mirror on the second substrate.

[0066] The optical device relating to item 6 is an optical device relating to any of items 1 to 5, wherein the film is a monolayer film.

[0067] In this optical device, the absorption and scattering of light by the monolayer can be almost ignored.

[0068] The optical device relating to item 7 is an optical device relating to any of items 1 to 6, comprising a structure that allows adjustment of the refractive index of the dielectric member. By changing the refractive index of the dielectric member, it is possible to change the direction of light emitted from the optical waveguide layer through the first substrate or the second substrate, or the incident direction of light taken into the optical waveguide layer through the first substrate or the second substrate.

[0069] This optical device allows you to change the direction of light emission when used as an optical scanning device, or the direction of light reception when used as an optical receiving device.

[0070] The optical device relating to item 8 further comprises a pair of electrodes sandwiching the optical waveguide layer, as described in item 7. The dielectric member includes a liquid crystal material or an electro-optical material. The refractive index of the dielectric member can be changed by applying a voltage to the pair of electrodes.

[0071] In this optical device, the direction of light emission as an optical scanning device, or the direction of light reception as an optical receiving device, can be changed by applying a voltage to a dielectric member containing a liquid crystal material or an electro-optical material using a pair of electrodes.

[0072] The optical device relating to item 9 is an optical device relating to item 8 in which the dielectric member is formed from a liquid crystal material. The film is a liquid crystal alignment film whose orientation direction is defined by rubbing.

[0073] This optical device allows for the orientation of liquid crystal materials.

[0074] The optical device relating to item 10 is an optical device relating to item 8 in which the dielectric member is formed from a liquid crystal material. The film is a liquid crystal alignment film whose orientation direction is defined by polarized irradiation.

[0075] In this optical device, even if protrusions are present on the first surface and / or the second surface, the liquid crystal material can be oriented on the surface of those protrusions.

[0076] The optical device relating to item 11 is an optical device relating to any of items 1 to 10, further comprising a plurality of phase shifters connected directly to the optical waveguide layer or via other waveguides. By changing the phase difference of the light passing through the plurality of phase shifters, the direction of light emitted from the optical waveguide layer via the first substrate or the second substrate, or the incident direction of light taken into the optical waveguide layer via the first substrate or the second substrate, is changed.

[0077] In this optical device, a phase shifter can be used to change the direction of light emission when used as an optical scanning device, or the direction of light reception when used as an optical receiving device.

[0078] The photodetection system relating to item 12 comprises an optical device relating to any of items 1 to 11, a photodetector that detects light emitted from the optical device and reflected from an object, and a signal processing circuit that generates distance distribution data based on the output of the photodetector.

[0079] This light detection system can generate distance measurement images.

[0080] The optical fiber relating to item 13 comprises a core extending in a first direction, a film bonded to the surface of the core via siloxane bonds, and a cladding located around the core and in contact with the film, wherein the refractive index of the cladding is lower than that of the core.

[0081] In this optical fiber, the bonding strength between the core and cladding can be improved by joining them via a film.

[0082] The optical fiber relating to item 14 is the optical fiber relating to item 13 in which the film is a monolayer film.

[0083] In this optical fiber, the bonding strength between the core and cladding can be improved by using a film with high adhesion and coating properties.

[0084] The optical fiber relating to item 15 is an optical fiber relating to item 13 in which the core is formed from quartz, the cladding is formed from acrylic resin, and the film is a monolayer having an alkyl group on the side opposite to the core.

[0085] In this optical device, the bonding strength between quartz and acrylic resin can be improved by using a monolayer containing alkyl groups.

[0086] In this disclosure, all or part of a circuit, unit, device, component, or part, or all or part of a functional block in a block diagram, may be implemented by one or more electronic circuits, including, for example, a semiconductor device, a semiconductor integrated circuit (IC), or a large-scale integration (LSI). The LSI or IC may be integrated on a single chip or may be composed of multiple chips combined. For example, functional blocks other than memory elements may be integrated on a single chip. Here, we refer to them as LSIs or ICs, but the name may change depending on the degree of integration, and they may also be called system LSIs, VLSIs (very large-scale integrations), or ULSIs (ultra-large-scale integrations). Field-programmable gate arrays (FPGAs) that are programmed after the manufacture of the LSI, or reconfigurable logic devices that allow for the reconfiguration of junction relationships within the LSI or the setup of circuit compartments within the LSI, can also be used for the same purpose.

[0087] Furthermore, the functions or operations of all or part of a circuit, unit, device, component, or part can be performed by software processing. In this case, the software is recorded on one or more non-temporary recording media such as ROMs, optical disks, or hard disk drives, and when the software is executed by a processor, the functions specified in the software are performed by the 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 necessary hardware devices, such as interfaces.

[0088] (Embodiment 1) The optical device 100 in Embodiment 1 of this disclosure can be fabricated, for example, by bonding a superstructure including a mirror 30 and a substructure including a mirror 40. For optical scanning by voltage application, the optical waveguide layer 20 may include, for example, a liquid crystal material. Prior to bonding, an alignment film for aligning the liquid crystal material may be provided on the surface of the superstructure and / or the surface of the substructure. For bonding the superstructure and the substructure, a sealing member such as an ultraviolet-curing resin or a thermosetting resin may be used. For example, vacuum sealing may be used to inject the liquid crystal material into the optical device 100. Injecting the liquid crystal material into a space surrounded by a sealing member can prevent vacuum leakage during the injection of the liquid crystal material.

[0089] The optical device in Embodiment 1 of this disclosure will be described below with reference to Figures 6A to 7C. Some explanations that overlap with those previously described may be omitted.

[0090] Figure 6A is a schematic diagram showing an example of the optical device 100 in Embodiment 1 of this disclosure, as viewed from the Z direction. However, the alignment film is omitted in Figure 6A. Figure 6B is a diagram obtained by omitting the superstructure 100b from Figure 6A. Figures 7A, 7B, and 7C are cross-sectional views of Figure 6A along the lines VIIA-VIIA, VIIB-VIIB, and VIIC-VIIC, respectively.

[0091] In the example shown in Figures 7A to 7C, the optical device 100 in this embodiment comprises a first substrate 50a and a second substrate 50b, a plurality of partition walls 73, a plurality of first optical waveguides 10 and a plurality of second optical waveguides 11, a sealing member 79, and a film 22. There is no limit to the number of first optical waveguides 10; there may be just one. The same applies to the second optical waveguides 11. In the following description, "first" and "second" will be omitted. The optical device 100 in this embodiment can be classified into a lower structure 100a, an upper structure 100b, and a film 22. However, the terms "upper" and "lower" do not limit the arrangement of the optical device 100.

[0092] In the example shown in Figures 7A to 7C, the substructure 100a comprises a substrate 50a, an electrode 62a, a mirror 40, a dielectric layer 51, a plurality of partition walls 73, a sealing member 79, and an optical waveguide 11. The electrode 62a is provided on the substrate 50a. The mirror 40 is provided on the electrode 62a. The dielectric layer 51 is provided on the mirror 40. The partition walls 73, the sealing member 79, and the optical waveguide 11 are provided on the dielectric layer 51. Note that the substrate 50a may be considered to include the mirror 40.

[0093] In the example shown in Figures 7A to 7C, the superstructure 100b comprises a substrate 50b, an electrode 62b, and a mirror 30. The electrode 62b is provided on the substrate 50b. The mirror 30 is provided on the electrode 62b. The reflective surface 30s of the mirror 30 and the reflective surface 40s of the mirror 40 face each other. Note that the substrate 50b may be considered to include the mirror 30.

[0094] In the example shown in Figures 7A to 7C, the film 22 is provided on the uppermost, lowermost, and outermost side surfaces of the lower structure 100a. The film 22 is provided on the surfaces of the substrate 50a, mirror 40, dielectric layer 51, partition wall 73, sealing member 79, and optical waveguide 11 that would be exposed if the film 22 were not present. Similarly, the film 22 is provided on the uppermost, lowermost, and outermost side surfaces of the upper structure 100b. The film 22 is provided on the surfaces of the substrate 50b, mirror 30, and electrode 62b that would be exposed if the film 22 were not present.

[0095] The configuration of the optical device 100 is described in detail below.

[0096] Of the substrates 50a and 50b, the substrate on the side from which light is emitted is translucent. Both substrates 50a and 50b may be translucent. Similarly, of the electrodes 62a and 62b, the electrode on the side from which light is emitted is translucent. Both electrodes 62a and 62b may be translucent. At least one of electrodes 62a and 62b may be formed from, for example, a transparent electrode. In the example shown in Figures 7A to 7C, light is emitted from the optical waveguide 10 through the electrode 62b and substrate 50b of the superstructure 100b.

[0097] Multiple partition walls 73 are aligned in the Y direction and are located between substrate 50a and substrate 50b. Each partition wall 73 extends along the X direction.

[0098] Multiple optical waveguides 10 are defined between multiple partitions 73. Each optical waveguide 10 comprises a mirror 30, a mirror 40, and an optical waveguide layer 20. In the example shown in Figures 6B to 7C, a portion of the dielectric layer 51 is removed, and a portion of the mirror 40 is exposed. The optical waveguide layer 20 is provided in the region enclosed by the mirror 30, the exposed portion of the mirror 40, and two adjacent partitions 73. The optical waveguide layer 20 includes a dielectric member 21. The dielectric member 21 includes, for example, a liquid crystal material or an electro-optic material. The optical waveguide 10 functions as the slow light waveguide described above. Mirror 30 is located between the substrate 50b and the optical waveguide layer 20. Mirror 40 is located between the substrate 50a and the optical waveguide layer 20.

[0099] The refractive index of the optical waveguide layer 20 is higher than that of the partition walls 73 and the dielectric layer 51. As a result, light propagating within the optical waveguide layer 20 does not leak into the partition walls 73 and the dielectric layer 51 directly beneath them. Light propagating within the optical waveguide layer 20 undergoes total internal reflection at the interfaces between the optical waveguide layer 20 and each partition wall 73, and at the interfaces between the optical waveguide layer 20 and the dielectric layer 51.

[0100] Electrodes 62a and 62b directly or indirectly sandwich the dielectric member 21. "Directly sandwiching" means sandwiching without the use of other members. "Indirectly sandwiching" means sandwiching through other members. By applying a voltage to electrodes 62a and 62b, the refractive index of the dielectric member 21 is adjusted. As a result, the emission angle of the light emitted from the optical waveguide 10 to the outside changes.

[0101] Furthermore, the optical waveguide 10 does not necessarily have to be a slow-light waveguide. The optical waveguide 10 may, for example, not include mirrors 30 and 40, and propagate light within the optical waveguide layer 20 by total internal reflection by the surfaces of substrate 50a and substrate 50b. In such an optical waveguide, light is emitted to the outside from the end of the optical waveguide 10, rather than through substrate 50a or substrate 50b.

[0102] The sealing member 79 fixes the gap between substrate 50a and substrate 50b. As shown in Figure 6B, the sealing member 79 surrounds the multiple optical waveguides 10 and the multiple partitions 73 when viewed from the Z direction. In the Y direction, the sealing member 79 is provided so as to straddle the optical waveguide 11. The upper surface of the sealing member 79 is parallel to the XY plane. The size of the sealing member 79 in the Z direction on the dielectric layer 51 is equal to or greater than the sum of the sizes of the partitions 73 and the mirrors 30 in the Z direction. The sealing member 79 may be formed from, for example, an ultraviolet-curing resin or a thermosetting resin. The material of the sealing member 79 does not need to be an ultraviolet-curing resin or a thermosetting resin, as long as it is a member that can maintain the gap between substrate 50a and substrate 50b for a long period of time.

[0103] Optical waveguide 11 is connected to optical waveguide 10. Light is supplied from optical waveguide 11 to optical waveguide 10. In the example shown in Figures 6A to 7C, optical waveguide 11 is located on a dielectric layer 51. The dielectric layer 51 is located between the substrate 50a and optical waveguide 11. By adjusting the size of the dielectric layer 51 in the Z direction, the light propagating through optical waveguide 11 can be coupled to optical waveguide 10 with high efficiency. The size of the dielectric layer 51 in the Z direction can be adjusted, for example, so that optical waveguide 11 is located near the center of the optical waveguide layer 20 in the Z direction. Optical waveguide 11 is a waveguide that propagates light by total internal reflection. For this reason, the refractive index of optical waveguide 11 is higher than the refractive index of the dielectric layer 51. Note that optical waveguide 11 may also be a slow light waveguide.

[0104] Each of the multiple optical waveguides 11 includes a portion located between two adjacent partitions among the multiple partitions 73. As shown in Figures 6B to 7C, each of the multiple optical waveguides 11 may have a grating 15 in that portion. The propagation constant of optical waveguide 11 is different from the propagation constant of optical waveguide 10. The grating 15 shifts the propagation constant of optical waveguide 11 by the reciprocal grid. When the propagation constant of optical waveguide 11, which has been shifted by the reciprocal grid, matches the propagation constant of optical waveguide 10, the light propagating through optical waveguide 11 is coupled to optical waveguide 10 with high efficiency.

[0105] When the dielectric member 21 is formed from liquid crystal material, after the lower structure 100a and the upper structure 100b are bonded together, the liquid crystal material is injected through the sealing port 79o shown in Figure 6B. After the injection of the liquid crystal material, the sealing port 79o is closed with the same material as the sealing member 79. The region thus sealed is entirely filled with liquid crystal material. This region is located between the substrate 50a and the substrate 50b and is surrounded by the sealing member 79. This region is filled with the same material as the dielectric member 21.

[0106] Next, the film 22 in this embodiment will be described. The film 22 in this embodiment is a monomolecular-weight oriented film bonded to the surface on which the film 22 is provided via siloxane bonds. Siloxane bonds have the advantages of improving the adhesion and coverage of the monomolecular-weight film, as well as being low-cost. The film 22 is provided on at least the reflective surface 30s of the mirror 30 and / or the reflective surface 40s of the mirror 40. In the example shown in Figures 7A to 7C, for the convenience of fabricating the optical device 100, the film 22 is also provided on surfaces other than the reflective surface 30s and / or the reflective surface 40s, but it is not necessarily required to provide these surfaces as well.

[0107] The monomolecule-oriented film has a thinner and more uniform thickness compared to the polyimide-oriented film. The thickness of the monomolecule-oriented film is approximately 2 nm, the size of a molecule. When light is incident on the thin and uniform monomolecule-oriented film, there is almost no absorption or scattering of light. Therefore, even if light undergoes multiple reflections and propagates along the X direction in the optical waveguide layer 20 as shown in Figure 2, the light is hardly absorbed or scattered by the monomolecule-oriented film. As a result, optical loss in the optical waveguide layer 20 can be suppressed.

[0108] Since the thin film 22 does not function as an insulating film, the film 22 provided on surfaces other than the reflective surface 30s and / or reflective surface 40s can be left as is. Therefore, the step of removing the film 22 can be omitted in the fabrication of the optical device 100. Depending on the application, the film 22 provided on surfaces other than the reflective surface 30s and / or reflective surface 40s may be removed.

[0109] The following describes the materials and sizes of the components used to fabricate the optical device 100 in the embodiment. Hereinafter, the size in the Z direction may be referred to as "thickness".

[0110] First, we will describe examples of the materials and sizes of the components of the substructure 100a.

[0111] The substrate 50a may be formed from, for example, an SiO2 layer. The size of the substrate 50a in both the X and Y directions may be, for example, 15 mm in both directions. The thickness of the substrate 50a may be, for example, 0.7 mm.

[0112] The electrode 62a may be formed from, for example, an ITO sputtered layer. The thickness of the electrode 62a may be, for example, 50 nm.

[0113] The mirror 40 may be a multilayer reflective film. The multilayer reflective film can be formed, for example, by alternately depositing and stacking Nb2O5 layers and SiO2 layers. The Nb2O5 layer has a refractive index n=2.282. The thickness of the Nb2O5 layer may be, for example, about 100 nm. The SiO2 layer has a refractive index n=1.468. The thickness of the SiO2 layer may be, for example, about 200 nm. The mirror 40 has, for example, 31 Nb2O5 layers and 30 SiO2 layers, for a total of 61 layers. The thickness of the mirror 40 may be, for example, 9.1 μm.

[0114] The dielectric layer 51 can be formed from, for example, an SiO2 vapor-deposited layer. The SiO2 vapor-deposited layer has a refractive index n = 1.468. The thickness of the SiO2 vapor-deposited layer may be, for example, about 1.0 μm.

[0115] The optical waveguide 11 may be formed from, for example, an Nb2O5 deposited layer. The Nb2O5 deposited layer has a refractive index n=2.282. The thickness of the Nb2O5 deposited layer may be, for example, about 300 nm. Gratings 15 and 13 may be formed on the optical waveguide 11. Grating 15 may have, for example, a duty cycle of 1:1 and a pitch of 640 nm. Grating 13 may have, for example, a duty cycle of 1:1 and a pitch of 680 nm. Gratings 15 and 13 may be formed by patterning using photolithography. The size of the optical waveguide 11 in the Y direction may be, for example, 10 μm.

[0116] The partition wall 73 may be formed from an SiO2 vapor-deposited layer. The SiO2 vapor-deposited layer has a refractive index n = 1.468. The thickness of the SiO2 vapor-deposited layer may be, for example, 1.0 μm. The size of the partition wall 73 in the Y direction may be, for example, 50 μm.

[0117] Within the optical waveguide layer 20, a portion of the dielectric layer 51 can be removed, for example, by patterning using photolithography. The thickness of the optical waveguide layer 20 may be, for example, 2.0 μm. The size of the optical waveguide layer 20 in the Y direction may be, for example, 10 μm.

[0118] Next, we will describe the details of the materials and sizes of the components of the superstructure 100b.

[0119] The substrate 50b may be formed from, for example, an SiO2 layer. Substrate 50 in the X and Y directions b The sizes are, for example, 8mm and 20mm respectively, and the substrate 50 b The thickness could be, for example, 0.7 mm.

[0120] The electrode 62b may be formed from, for example, an ITO sputtered layer. The thickness of the electrode 62b may be, for example, 50 nm.

[0121] The mirror 30 may be a multilayer reflective film. The multilayer reflective film can be formed by alternately depositing and stacking Nb2O5 layers and SiO2 layers. The Nb2O5 layer has a refractive index n=2.282. The thickness of the Nb2O5 layer may be, for example, about 100 nm. The SiO2 layer has a refractive index n=1.468. The thickness of the SiO2 layer may be, for example, about 200 nm. The mirror 30 has, for example, 7 Nb2O5 layers and 6 SiO2 layers, for a total of 13 layers. The thickness of the mirror 30 may be, for example, 1.9 μm.

[0122] 5CB liquid crystal is used for the dielectric member 21. The material for the film 22 and the method for providing the film 22 will be described later.

[0123] For the seal member 79, an ultraviolet curable adhesive 3026E made by Three Bond is used. By irradiating ultraviolet rays with a wavelength of 365 nm and an energy density of 100 mJ / cm 2 , the seal member 79 is cured, and the lower structure 100a and the upper structure 100b provided with the film 22 are bonded together. By this bonding, the optical device 100 in the present embodiment is obtained.

[0124] Note that the substrates 50a and 50b do not have to be formed of SiO2. The substrates 50a and 50b may be, for example, inorganic substrates such as glass or sapphire, or resin substrates such as acrylic or polycarbonate. These inorganic substrates and resin substrates have translucency.

[0125] The transmittance of the mirror 30 from which light is emitted is, for example, 99.9%, and the transmittance 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 reflection film. As a combination of two layers in the multilayer reflection film, for example, the refractive index of one layer is 2 or more, and the refractive index of the other layer is less than 2. If the difference between the two refractive indices is large, a high reflectance can be obtained. The layer with a refractive index of 2 or more is formed of at least one selected from the group consisting of, for example, SiN x , AlN x , TiO x , ZrO x , NbO x , and TaO x . The layer with a refractive index of less than 2 is formed of at least one selected from the group consisting of, for example, SiO x and AlO x .

[0126] The refractive index of the dielectric layer 51 is, for example, less than 2, and the refractive index of each optical waveguide 11 is, for example, 2 or more. If the difference between the two refractive indices is large, the evanescent light leaking from each optical waveguide 11 into the dielectric layer 51 can be reduced.

[0127] Next, with reference to Figures 8A to 8E, the material of the film 22 in this embodiment and the method of providing the film 22 will be described. Figures 8A to 8E are diagrams illustrating the film 22 in this embodiment.

[0128] As shown in Figure 8A, a film is formed by bringing a solution 23 containing at least a silane compound into contact with the lower structure 100a and / or upper structure 100b, thereby chemically adsorbing the silane compound and bonding via siloxane bonds. In the molecule 23m shown in Figure 8A, the elliptical portion 23m1 represents a siloxane bond, the thin and long portion 23m2 represents a carbon-hydrogen bond, and the thick and short portion 23m3 represents other types of bonds.

[0129] Next, as shown in Figure 8B, by dissolving and removing the excess silane compound that has not been chemically adsorbed in the washing solution 24, the above film becomes a monolayer 22 bonded via siloxane bonds.

[0130] The method for oriented the monolayer 22 is as follows. The monolayer 22 can be oriented by draining the cleaning solution 24, as shown in Figure 8B. The upward arrow indicates the direction in which the lower structure 100a and / or upper structure 100b are pulled up, and the downward arrow indicates the orientation direction. Alternatively, if the monolayer 22 bonded via siloxane bonds has photosensitive groups, as shown in Figure 8C, the photosensitive groups are crosslinked or polymerized by irradiating the film 22 with polarized light 26p obtained by passing unpolarized ultraviolet light 26 through a polarizer 25, as shown in Figure 8D. The thick line indicates crosslinking. As a result, the monolayer 22 becomes a mono-oriented film with uniform orientation anisotropy relative to the liquid crystal. Alternatively, by rubbing the surface of the monolayer bonded via siloxane bonds, the monolayer 22 becomes a mono-oriented film exhibiting orientation anisotropy.

[0131] Whether a monomolecule-oriented film was oriented by polarized light irradiation or by rubbing can be determined by whether or not there are scratches on the film. Polarized light irradiation does not scratch the monomolecule-oriented film. On the other hand, rubbing does scratch the monomolecule-oriented film.

[0132] As shown in Figure 8E, the liquid crystal material 21, which is composed of rod-shaped molecules, is oriented in a specific direction by the single-molecule alignment film 22.

[0133] The solution 23 containing the silane compound mentioned above refers to a solution in which the silane compound is dissolved in a solvent, but it is also possible that some of the silane compound remains undissolved. A typical example of such a solution is a supersaturated solution.

[0134] The following (1) to (5) specifically illustrate silane compounds that can be used in the method for producing the above-described film 22. (1) SiY p Cl 3-p (2) CH3-(CH2) r SiY q Cl 3-q (3) CH3(CH2) s O(CH2) t SiY q Cl 3-q (4) CH3(CH2) u -Si(CH3)2(CH2) v -SiY q Cl3- q (5)CF3COO(CH2) w SiY q Cl 3-q However, p represents an integer from 0 to 3, q ​​represents an integer from 0 to 2, r represents an integer from 1 to 25, s represents an integer from 0 to 12, t represents an integer from 1 to 20, u represents an integer from 0 to 12, v represents an integer from 1 to 20, and w represents an integer from 1 to 25. Y represents one selected from the group consisting of hydrogen, alkyl groups, alkoxyl groups, fluorinated alkyl groups, and fluorinated alkoxy groups.

[0135] Furthermore, (6) through (14) below specifically illustrate trichlorosilane compounds. (6) CF3(CH2)9SiCl3 (7)CH3(CH2)9OSiCl3 (8)CH3(CH2)9Si(CH3)2(CH2) 10 SiCl3 (9)CH3COO(CH2) 15 SiCl3 (10)CF3(CF2)7-(CH2)2-SiCl3 (11) CF3(CF2)7-C6H4-SiCl3 (12)C6H5-CH=CH-CO-O-(CH2)6-O-SiCl3 (13)C6H5-CO-CH=CH-C6H4-O-(CH2)6-O-SiCl3 (14)C6H5-CH=CH-CO-C6H4-O-(CH2)6-O-SiCl3

[0136] Compound (12) has a photosensitive cinnamoyl group. Compounds (13) and (14) also have a photosensitive chalconyl group. The photosensitive base polymerizes upon irradiation with ultraviolet light. Furthermore, instead of the above chlorosilane compounds, isocyanate-based silane compounds in which the chlorosilyl group is replaced with an isocyanate group, or alkoxy-based silane compounds in which the chlorosilyl group is replaced with an alkoxy group may be used.

[0137] For example, instead of chlorosilane (6), the following isocyanate silane compounds (15) or alkoxy silane compounds (16) may be used. (15)CH3(CH2)9Si(OC2H5)3 (16)CH3(CH2)9Si(NCO)3

[0138] Using isocyanate-based silane compounds or alkoxy-based silane compounds has the advantage of not generating hydrochloric acid during chemical bonding, thus preventing damage to the equipment and making the work easier.

[0139] Next, we will describe a process for forming a thin film on the surface of a substrate using a silane compound, as well as the solvent and substrate used in that process.

[0140] The following chemical formula (1) shows the reaction steps when CF3-(CF2)7-(CH2)2-SiCl3, shown as compound (10), is brought into contact with a glass substrate as a silane compound. [ka]

[0141] The initial dehydrochlorination reaction shown in chemical formula (1) is a chemiadsorption reaction. When a silane compound solution is brought into contact with a glass substrate having OH groups, a dehydrochlorination reaction occurs. In this reaction, one end of the silane compound molecule chemically bonds to the OH group portion on the substrate surface. This reaction is a reaction between the SiCl group of the silane compound and the OH group. If the silane compound solution contains a large amount of water, the reaction with the substrate is inhibited. 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 OH groups, and it is also desirable to carry out the reaction in a low-humidity atmosphere. Details of the humidity conditions will be described later. Subsequently, after H2O hydrolysis and drying / dehydration, a film bonded via siloxane bonds is formed on the surface of the glass substrate.

[0142] Examples of silane solvents that can be used in this embodiment include at least one selected from the group consisting of water-free hydrocarbon solvents, fluorocarbon solvents, and silicone solvents. Examples of petroleum-based solvents that can be used in this embodiment include petroleum naphtha, solvent naphtha, petroleum ether, petroleum benzine, isoparaffin, normal paraffin, decalin, industrial gasoline, kerosene, ligroin, and dimethyl C At least one selected from the group consisting of ricone, phenyl silicone, alkyl-modified silicone, and polyester silicone is mentioned. In addition, at least one fluorocarbon-based solvent that can be used in this embodiment is selected from the group consisting of fluorocarbon-based solvents, Fluorinert (3M product), and Aflud (Asahi Glass product). These solvents may be used individually or in combination of two or more compatible solvents.

[0143] In particular, silicones contain very little moisture and are not easily hygroscopic. Furthermore, silicones solvate chlorosilane compounds, preventing them from coming into direct contact with moisture. Therefore, when a solution consisting of chlorosilane compounds and silicone is brought into contact with a substrate, the chlorosilane compounds can be chemically adsorbed onto the exposed OH groups in the substrate while preventing adverse effects from moisture in the surrounding atmosphere.

[0144] Considering the provision of film 22, the optical waveguide 11, mirror 30, mirror 40, dielectric layer 51, and partition wall 73 in the optical device 100 can be formed from the following materials. Of these materials, the material with a refractive index of 2 or more is SiN x AlN x , TiO x ZrO x NbO x , and TaO x It is at least one selected from the group consisting of the following. Among these materials, the material with a refractive index of less than 2 is SiO x and AlO x It is at least one selected from the group consisting of the following. The material can secure a large number of OH groups, which are adsorption sites for silane compounds. Therefore, an orientation film with excellent orientation characteristics can be formed on the surface of the material.

[0145] On the other hand, electrodes 62a and 62b in the optical device 100 may 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 100 may be formed from a polymer material such as an acrylic or silicone-based material. These conductive materials and polymer materials have few OH groups, which are adsorption sites for silane compounds. Therefore, when an alignment film is formed on the surface of these materials, a hydrophilization treatment is applied to the surface to generate or increase the number of OH groups. As this hydrophilization treatment, an SiO2 film or SiN film may be applied to the surface. x Applying a film or generating OH groups on the surface through UV-O3 treatment are effective methods.

[0146] Furthermore, if the height of the protrusions from the surface of the lower structure 100a and / or upper structure 100b is 40 nm or more, rubbing will result in unevenness caused by the protrusions. In structures where the protrusions are integrated, the height of the protrusions may reach 50 μm. Rubbing can cause the protrusions to break. On the other hand, with polarized irradiation, the orientation direction can be specified even at locations where the protrusions are adjacent or intersecting. The protrusions are not broken. Polarized irradiation is effective for protrusions having any shape other than an inverse taper shape.

[0147] Cleaning methods in this embodiment include, for example, immersion and steam cleaning. In particular, steam cleaning can powerfully remove excess silane compounds that have not been chemically adsorbed from the entire surface of the lower structure 100a and / or upper structure 100b by the penetrating power of steam. Cleaning solvents that can be used in this embodiment include, for example, at least one selected from the group consisting of water-free hydrocarbon solvents, fluorocarbon solvents, and silicone solvents. Petroleum-based cleaning solvents that can be used in this embodiment include, for example, petroleum naphtha, solvent naphtha, petroleum ether, petroleum benzine, isoparaffin, normal paraffin, decalin, industrial gasoline, kerosene, ligroin, and dimethyl C At least one selected from the group consisting of ricone, phenyl silicone, alkyl-modified silicone, and polyester silicone is included. In addition, at least one fluorocarbon-based solvent that can be used in this embodiment is selected from the group consisting of fluorocarbon-based solvents, Fluorinert (3M product), and Aflud (Asahi Glass product). These solvents may be used individually or in combination of two or more compatible types.

[0148] As an orientation method by liquid draining in this embodiment, as shown in Figure 8B, one method is to hold the surfaces of the lower structure 100a and / or upper structure 100b vertically and drain the cleaning liquid. This allows for draining of the cleaning liquid only in the vertical direction. In particular, when draining cleaning liquids with a boiling point of 200°C or lower, the drying performance after draining is excellent. Furthermore, chloroform is excellent at removing chlorosilane polymers produced by the reaction of chlorosilane and water.

[0149] In this embodiment, one orientation method by deliquing involves blowing gas onto the surface of the lower structure 100a and / or the upper structure 100b to deliquer the cleaning solution. This allows for quick deliquing of the cleaning solution only in the direction from which the gas is blown. In particular, when deliquing cleaning solutions with a boiling point of 150°C or higher, evaporation of the cleaning solution does not occur even when gas is blown onto it. Furthermore, N-methyl-2-pyrrolidinone is excellent at removing chlorosilane polymers produced by the reaction of chlorosilane with water.

[0150] In the polarization irradiation orientation applicable to this embodiment, the irradiated polarized ultraviolet light may have a wavelength distribution of 300 nm to 400 nm. The irradiation dose is approximately 50 mJ / cm² at 365 nm. 2 More than about 2000mJ / cm 2 The following applies, especially regarding 1000 mJ / cm². 2 At irradiation doses above this level, the orientation of the liquid crystal material tends to become homogeneous. Conversely, at irradiation doses below 100 mJ / cm2, the orientation of the liquid crystal material tends to become pre-tilted.

[0151] Next, we will explain the results of measuring the light emitted from the optical device 100 in this embodiment.

[0152] Figure 9 schematically shows the emission of light from the optical device 100. In the example shown in Figure 9, the light emitted from the optical device 100 was measured by a photodetector (not shown) fixed in the direction of the emission angle θ = 60°. In this measurement, 589 nm laser light was input to each optical waveguide 11 via the grating 13. When the film 22 was a monomolecular oriented film having siloxane bonds, the measured light intensity was approximately twice as high as when the film 22 was a polyimide oriented film. That is, it was found that the optical loss was approximately 50% in the case of a polyimide oriented film.

[0153] Polyimide alignment films are commonly used in liquid crystal displays (LCDs). In LCDs, light passes through the alignment films on the upper and lower substrates only once. Therefore, even with thick and non-uniform polyimide alignment films, light loss due to absorption and scattering in the alignment films is not a significant problem for a single transmission.

[0154] In the optical device 100 of this embodiment, as described above, light propagates through the optical waveguide layer 20 while being multiple-reflected by the reflective surfaces 30s and 40s, which include the film 22. Therefore, in the case of a polyimide alignment film, the light loss due to absorption and scattering in the alignment film becomes large. In contrast, in the case of a polyimide alignment film that is thin and uniform at the molecular level, even if light is multiple-reflected, the light loss due to absorption and scattering in the alignment film can be ignored. As a result, the light loss can be reduced and the intensity of the emitted light can be greatly improved.

[0155] In the example described above, multiple partitions 73 are placed between mirror 30 and mirror 40. Alternatively, a planar optical waveguide comprising mirror 30, mirror 40, and optical waveguide layer 20 may be connected to multiple optical waveguides 11 without the provision of multiple partitions 73. Light propagating through the multiple optical waveguides 11 interferes within the optical waveguide layer 20 in the planar optical waveguide to form an optical beam. The optical beam formed within the optical waveguide layer 20 is emitted to the outside via mirror 30 and substrate 50b.

[0156] <Application Examples> Figure 10 shows an example configuration of an optical scanning device 100, which integrates elements such as an optical splitter 90, a waveguide array 10A, a phase shifter array 80A, and a light source 130 on a circuit board (for example, a chip). The light source 130 may be a light-emitting element such as a semiconductor laser. In this example, the light source 130 emits light of a single wavelength, with a wavelength of λ in free space. The optical splitter 90 splits the light from the light source 130 and introduces it into waveguides in a plurality of phase shifters. In the example shown in Figure 10, an electrode 62A and a plurality of electrodes 62B are provided on the chip. Control signals are supplied to the waveguide array 10A from electrode 62A. Control signals are sent to the plurality of phase shifters 80 in the phase shifter array 80A from the plurality of electrodes 62B. Electrodes 62A and the plurality of electrodes 62B may be connected to a control circuit (not shown) that generates the above control signals. The control circuit may be provided on the chip shown in Figure 10, or on another chip in the optical scanning device 100.

[0157] As shown in Figure 10, by integrating all components onto a chip, wide-area optical scanning can be achieved with a small device. For example, on a chip of about 2 mm x 1 mm, 10 All the components shown can be integrated.

[0158] Figure 11 is a schematic diagram showing a two-dimensional scan being performed by irradiating a light beam, such as a laser, from an optical scanning device 100 to a distant object. The two-dimensional scan is performed by moving the beam spot 310 in the horizontal and vertical directions. For example, by combining it with the known TOF (Time of Flight) method, a two-dimensional distance measurement image can be obtained. The TOF method is a method of determining distance by calculating the time of flight of light by irradiating a laser and observing the reflected light from the object.

[0159] Figure 12 is a block diagram showing an example configuration of a LiDAR system 300, which is an example of a photodetection system capable of generating such a ranging image. The LiDAR system 300 comprises an optical scanning device 100, a photodetector 400, a signal processing circuit 600, and a control circuit 500. The photodetector 400 detects light emitted from the optical scanning device 100 and reflected from an object. The photodetector 400 may be, for example, an image sensor sensitive to the wavelength λ of light emitted from the optical scanning device 100, or a photodetector including a light-receiving element such as a photodiode. The photodetector 400 outputs an electrical signal corresponding to the amount of light it has received. The signal processing circuit 600 calculates the distance to the object based on the electrical signal output from the photodetector 400 and generates distance distribution data. The distance distribution data is data showing a two-dimensional distribution of distance (i.e., a ranging image). The control circuit 500 is a processor that controls the optical scanning 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 scanning device 100 and the timing of exposure and signal readout of the photodetector 400, and instructs the signal processing circuit 600 to generate a distance measurement image.

[0160] In 2D scanning, the frame rate for acquiring distance measurement images can be selected from commonly used video frame rates such as 60fps, 50fps, 30fps, 25fps, and 24fps. Furthermore, considering applications in automotive systems, a higher frame rate increases the frequency of acquiring distance measurement images, enabling more accurate obstacle detection. For example, when driving at 60 km / h, a 60fps frame rate allows an image to be acquired approximately every 28 cm the car moves. A 120fps frame rate allows an image to be acquired approximately every 14 cm the car moves. A 180fps frame rate allows an image to be acquired approximately every 9.3 cm the car moves.

[0161] The time required to acquire one ranging image depends on the beam scanning speed. For example, to acquire a 100x100 resolution image at 60fps, the beam scan needs to be performed at a rate of 1.67μs or less per point. In this case, the control circuit 500 controls the emission of the optical beam by the optical scanning device 100 and the signal accumulation and readout by the photodetector 400 at an operating speed of 600kHz.

[0162] <Examples of applications in optical receiving devices> The optical scanning devices in the aforementioned embodiments of this disclosure can also be used as optical receiving devices with substantially the same configuration. The optical receiving device comprises the same waveguide array 10A as the optical scanning device and a first adjustment element for adjusting the direction of receivable light. Each first mirror 30 of the waveguide array 10A transmits light incident from a third direction to the opposite side of the first reflecting surface. Each optical waveguide layer 20 of the waveguide array 10A propagates light that has passed through the first mirror 30 in a second direction. The first adjustment element can change the direction of receivable light by changing at least one of the refractive index and thickness of the optical waveguide layer 20 in each waveguide element 10, as well as the wavelength of light. Furthermore, the optical receiving device comprises the same plurality of phase shifters 8 as the optical scanning device. 0 and Multiple waveguide elements 10 to multiple phase shifters 8 0 If a second adjustment element is provided that changes the phase difference of the light that passes through and is output, the direction of the receivable light can be changed in two dimensions.

[0163] For example, an optical receiving device can be constructed by replacing the light source 130 in the optical scanning device 100 shown in Figure 10 with a receiving circuit. When light of wavelength λ is incident on the waveguide array 10A, the light is sent to the optical splitter 90 through the phase shifter array 80A, finally collected at one point, and sent to the receiving circuit. The intensity of the light collected at that point can be said to represent the sensitivity of the optical receiving device. The sensitivity of the optical receiving device can be adjusted by adjustment elements separately incorporated into the waveguide array and the phase shifter array 80A. In the optical receiving device, for example in Figure 4, the direction of the wave vector (thick arrow in the figure) is reversed. 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 direction of the arrangement of the waveguide element 10 (Y direction in the figure). The sensitivity of the optical component in the X direction can be adjusted by an adjustment element incorporated into the waveguide array 10A. On the other hand, the sensitivity of the optical component in the alignment direction of the waveguide element 10 can be adjusted by an adjustment element incorporated into the phase shifter array 80A. From the phase difference Δφ of the light when the sensitivity of the optical receiving device is maximized, the refractive index nw of the optical waveguide layer 20, and its thickness d, θ and α0 shown in Figure 4 can be determined. This allows the direction of incident light to be identified.

[0164] (Embodiment 2) Next, with reference to Figure 13, an optical device in Embodiment 2 of this disclosure will be described. This optical device is an optical fiber comprising a core and cladding.

[0165] Figure 13 is a schematic diagram showing an example of an optical fiber 100F in Embodiment 2 of the present disclosure. In the example shown in Figure 13, the optical fiber 100F in Embodiment 2 comprises a core 100c, a cladding 100d, and a film 22. The core 100c has a structure that extends in the X direction. The same applies to the film 22 and the cladding 100d. The film 22 is a monolayer bonded to the surface of the core 100c via siloxane bonds. The film 22 is as described above. The cladding 100d is located around the core 100c via the film 22. The cladding 100d is in contact with the film 22c. The refractive index of the cladding 100d is lower than that of the core 100c. Light can propagate through the core 100c along the X direction by total internal reflection.

[0166] As mentioned above, the film 22 has excellent adhesion and covering properties. Therefore, if the core 100c is formed from quartz and the cladding 100d is formed from acrylic resin, and the film 22 is a monolayer 22 having an alkyl group on the opposite side of the core 100c, then joining the core 100c and cladding 100d via the film 22 will result in a stronger bond than directly joining the core 100c and cladding 100d. Furthermore, as mentioned above, the light loss due to the film 22 is almost negligible, so there is almost no loss of light propagating through the core 100c.

[0167] The embodiments described above can be combined as appropriate. [Industrial applicability]

[0168] The optical scanning device and optical receiving device in the embodiments of this disclosure can be used in applications such as lidar systems mounted on vehicles such as automobiles, UAVs, and AGVs. [Explanation of symbols]

[0169] 10 Waveguide elements, optical waveguides 11 Optical waveguide 10A waveguide array 13 Gratings 15 Gratings 20 Optical waveguide layer 20L light 21 Dielectric material 22 membrane 30 First Mirror 40 Second Mirror 50a, 50b substrates 51 Dielectric layer 62a, 62b, 62A, 62B electrode 73 Multiple partitions 80 Phase Shifter 80A Phase Shifter Array 90. Optical splitter 100 Optical Scanning Devices 100F Optical Fiber 110 Waveguide Array Driving Circuit 120 Phase Shifter Array Driving Circuit 130 light source 310 Beam Spot 400 photodetectors 500 control circuit 600 Signal Processing Circuits

Claims

1. A first substrate having a first surface extending in a first direction and a second direction intersecting the first direction, the first substrate including a first mirror having the first surface, A second substrate having a second surface opposite to the first surface, the second substrate including a second mirror having the second surface, A film provided on the first surface and / or the second surface, which is a monomolecular oriented film having siloxane bonds, At least one optical waveguide layer located between the first substrate and the second substrate, comprising a dielectric member in contact with the film, and guiding light in the first and / or second directions, Equipped with, Optical devices.

2. The optical waveguide further comprises at least one optical waveguide connected to the optical waveguide layer. The optical device according to claim 1.

3. The tip portion of the optical waveguide is located between the first substrate and the second substrate. The optical waveguide includes a first grating at its tip portion. The optical device according to claim 2.

4. The optical waveguide includes a portion that does not overlap with either the first substrate or the second substrate when viewed from a direction perpendicular to the first surface. The optical waveguide includes a second grating in the non-overlapping portion. The optical device according to claim 2 or 3.

5. The dielectric material has a structure that allows the refractive index to be adjusted, By changing the refractive index of the dielectric member, it is possible to change the direction of light emitted from the optical waveguide layer through the first substrate or the second substrate, or the incident direction of light taken into the optical waveguide layer through the first substrate or the second substrate. The optical device according to any one of claims 1 to 4.

6. The optical waveguide layer is further comprising a pair of electrodes sandwiching the optical waveguide layer, The dielectric member includes a liquid crystal material or an electro-optical material. By applying a voltage to the pair of electrodes, it is possible to change the refractive index of the dielectric member. The optical device according to claim 5.

7. The dielectric member is formed from a liquid crystal material, The aforementioned film is a liquid crystal alignment film whose orientation direction is defined by rubbing. The optical device according to claim 6.

8. The dielectric member is formed from a liquid crystal material, The aforementioned film is a liquid crystal alignment film whose orientation direction is determined by polarized light irradiation. The optical device according to claim 6.

9. The optical waveguide layer further comprises a plurality of phase shifters connected directly or via other waveguides, The optical device according to any one of claims 1 to 8, wherein the direction of light emitted from the optical waveguide layer via the first substrate or the second substrate, or the incident direction of light taken into the optical waveguide layer via the first substrate or the second substrate, is changed by changing the phase difference of light passing through the plurality of phase shifters.

10. An optical device according to any one of claims 1 to 9, A photodetector that detects light emitted from the optical device and reflected from an object, A signal processing circuit that generates distance distribution data based on the output of the photodetector, Equipped with, Light detection system.

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