Optical waveguide structure

Abstract

To allow a chip having waveguides to have a function of acquiring guided light so as to perform correction for restraining a variation in the phase of the guided light propagated in the multiple waveguides in an optical waveguide structure.SOLUTION: A light radiation section 34 is provided in each of multiple waveguides 22 on a board 12. Then, the light radiation section 34 radiates one portion of guided light 22a propagated to the waveguide 22 through a phase shifter 24 in a direction different from a direction in which an optical antenna section 26 radiates it to the outside from the waveguide 22. A photoelectric converter 16 is provided on the board 12, and is disposed in one side or the other side in a second direction D2 relative to all the light radiation sections 34 that an optical phased array 18 has. Further, the arrangement position of the photoelectric converter 16 is determined such that radiation beams composed of radiation light impinge on the photoelectric converter 16 when phases of the radiation light radiated from each light radiation section 34 from among the multiple waveguides 22 are lined up mutually.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present disclosure relates to an optical waveguide structure having a plurality of waveguides that propagate light. [Background technology]

[0002] Patent Document 1 describes a phase measurement device that acquires output light emitted from multiple waveguides that constitute an optical phased array and measures the phase variation that occurs in each waveguide. The phase measurement device in Patent Document 1 includes a camera that serves as an output light acquisition unit that acquires the output light emitted from the optical phased array, separate from the optical phased array. The phase measurement device in Patent Document 1 then calculates the phase variation that occurs in each waveguide based on image information obtained from the camera. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-79493 Summary of the Invention [Problem to be solved by the invention]

[0004] In an optical phased array composed of multiple waveguides, variations in the phase of guided light propagating through each waveguide occur due to processing errors during manufacturing, component variations, etc. Therefore, it is necessary to correct the guided light in each waveguide to suppress the phase variations. As a device for performing corrections to suppress the phase variations of guided light, for example, a phase measurement device has been proposed in Patent Document 1.

[0005] However, the phase measurement device of Patent Document 1 requires a camera for acquiring emitted light separate from the chip having the optical phased array, making the entire device large. For this reason, it was considered preferable to give the chip having the optical phased array the function of acquiring guided light from each waveguide included in the optical phased array.

[0006] Here, in order to provide a chip having an optical phased array with the function of acquiring the guided light of each waveguide, it is conceivable to provide, for example, an optical coupling waveguide between each waveguide of the optical phased array for acquiring the guided light, which is optically coupled to each waveguide. However, this has disadvantages. This is because, in this case, the optical coupling waveguide and various elements connected thereto would be arranged between each waveguide that propagates the guided light, which would impose limitations on narrowing the pitch of the waveguide arrangement. Furthermore, limitations on narrowing the pitch of the waveguide arrangement would also limit the scanning range of the beam formed by the output light of the optical phased array. The inventors have found the above as a result of detailed studies.

[0007] In view of the above, the present disclosure aims to provide a chip having a plurality of waveguides in an optical waveguide structure with a function for acquiring the guided light in order to correct the phase variation of the guided light propagating through the waveguides, while realizing a configuration that does not hinder the arrangement of the waveguides at a narrower pitch. [Means for solving the problem]

[0008] In order to achieve the above object, an optical waveguide structure according to one aspect of the present disclosure comprises: A substrate (12); a plurality of waveguides (22) that are provided on a substrate, extend in a first direction (D1), and are arranged so as to be aligned at a uniform pitch (Pd) in a second direction (D2) perpendicular to the first direction, and that propagate light; a plurality of phase adjusters (24) provided on the substrate for each of the plurality of waveguides, each of which adjusts the phase of light propagating through the waveguide; a plurality of optical antenna units (26) provided on the substrate in each of the plurality of waveguides, each of which radiates light that passes through the phase adjuster and propagates to the waveguide from the waveguide in an antenna unit radiation direction (Dan); a plurality of light radiating sections (34) provided on the substrate in the plurality of waveguides, each of which radiates a portion of light that passes through the phase adjuster and propagates into the waveguide as radiated light from the waveguide in a direction different from the radiation direction of the antenna section; a photoelectric converter (16, 161, 162) provided on the substrate, arranged on one side or the other side or both sides in the second direction with respect to the plurality of light emitting units, and outputting an electrical signal according to the intensity of the incident light; The position of the photoelectric converter is determined so that when the phases of the light emitted from each of the multiple light emitting sections are aligned, the radiation beams (Ba, B1a, B2a) formed by the light are incident on the photoelectric converter.

[0009] In this way, a portion of the guided light propagating through each waveguide is emitted as radiation light from each of the plurality of light emitting portions, and when the phases of the radiation lights are aligned, the emitted radiation light becomes a radiation beam and enters the optoelectronic converter. Therefore, the optoelectronic converter can acquire the guided light in order to correct for phase variations in the guided light in the plurality of waveguides. Furthermore, because the optoelectronic converter is provided on a common substrate together with the plurality of waveguides, it is possible to impart the function of acquiring the guided light to a chip having a plurality of waveguides.

[0010] Furthermore, since the photoelectric converter is disposed on one side or the other side, or both sides, of the plurality of light emitting portions in the second direction, the arrangement of the waveguides is not hindered by the arrangement of the photoelectric converter, and it can be said that the arrangement of the waveguides is less likely to be hindered by the arrangement of the photoelectric converter, compared to when various elements such as photoelectric converters are disposed between the waveguides that propagate the guided light.

[0011] In addition, in each section of the application documents, each element may be assigned a reference symbol in parentheses. In this case, the reference symbol merely indicates an example of the correspondence between the element and the specific configuration described in the embodiment described below. Therefore, the present disclosure is not limited in any way by the description of the reference symbol. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a conceptual diagram illustrating a schematic configuration of a general optical phased array. [Figure 2] 1. FIG. 2 is a diagram illustrating the configuration of a first reference example using a conceptual diagram similar to that of FIG. 1, and also illustrates a state in which the phases of guided light propagating through each waveguide are not uniform. [Figure 3] FIG. 3 is a diagram showing the distribution of the light intensity of the emitted light with respect to the azimuth from the optical antenna unit of the optical phased array in the state shown in FIG. 2, in which the phases of the guided light propagating through each waveguide are not uniform. [Figure 4] FIG. 10 is a diagram illustrating the configuration of the first reference example using a conceptual diagram similar to that of FIG. 1, and also illustrates a state in which the phases of the guided light propagating through each waveguide are aligned, and corresponds to FIG. 2. [Figure 5] FIG. 5 is a diagram showing the distribution of the light intensity of the output light with respect to the direction from the optical antenna unit of the optical phased array in the state of FIG. 4 in which the phases of the guided light propagating through each waveguide are aligned, and corresponds to FIG. 3 . [Figure 6] FIG. 10 is a first diagram schematically illustrating a general configuration of a second reference example using a conceptual diagram similar to that of FIG. [Figure 7] FIG. 7 is a second diagram schematically illustrating the configuration of the second reference example, and is a top view illustrating part VII of FIG. 6 with a reduced number of waveguides. [Figure 8] FIG. 10 is a perspective view schematically showing an optical antenna portion provided in each waveguide in the second reference example and the first embodiment. [Figure 9] FIG. 1 is a conceptual diagram schematically illustrating a general configuration of an optical waveguide structure according to a first embodiment. [Figure 10]FIG. 10 is a diagram illustrating a portion X in FIG. 9 in the first embodiment, and is a top view schematically illustrating a part of an optical phased array and an optoelectric converter provided on a substrate in the optical waveguide structure. [Figure 11] FIG. 11 is a cross-sectional view schematically showing a cross section taken along line XI-XI in FIG. 10 in the first embodiment. [Figure 12] FIG. 11 is a partially enlarged view showing a portion XII of FIG. 10 in the first embodiment. [Figure 13] FIG. 11 is a cross-sectional view schematically showing the XIII-XIII cross section of FIG. 10 in the first embodiment. [Figure 14] FIG. 11 is a top view similar to FIG. 10, illustrating a state in which the phases of the light radiated from the light radiating units of the optical phased array vary and are not aligned. [Figure 15] FIG. 15 is a light intensity distribution diagram showing the relationship between the orientation from the center of the light emitting portion group and the light intensity of the radiated light in a planar view along the third direction, in the state of FIG. 14 where the phases of the radiated light radiated from each light emitting portion are not uniform and vary. [Figure 16] FIG. 11 is a top view similar to FIG. 10, illustrating a state in which the phases of the light beams emitted from the light emitting units of the optical phased array are aligned with each other. [Figure 17] 17 is a light intensity distribution diagram showing the relationship between the direction from the center of the light emitting portion group in a plan view and the light intensity of the radiated light in the state of FIG. 16 in which the phases of the radiated light emitted from each light emitting portion are aligned with each other. [Figure 18] FIG. 11 is a top view schematically illustrating a part of an optical phased array and an optoelectric converter provided on a substrate in the optical waveguide structure in the second embodiment, and corresponds to FIG. 10 . [Figure 19] 19 is a partially enlarged view showing a portion XIX of FIG. 18 in the second embodiment, and corresponds to FIG. 12. FIG. [Figure 20] FIG. 11 is a top view schematically illustrating a part of an optical phased array and an optoelectric converter provided on a substrate in an optical waveguide structure in a third embodiment, and corresponds to FIG. 10 . [Figure 21]13. FIG. 21 is a cross-sectional view schematically showing a cross section taken along line XXI-XXI of FIG. 20 in the third embodiment, and corresponds to FIG. [Figure 22] 22 is a partially enlarged view showing a portion XXII of FIG. 20 in the third embodiment, and corresponds to FIG. 12. FIG. [Figure 23] FIG. 18 is a light intensity distribution diagram showing the relationship between the direction from the center of the light emitting portion group in a plan view and the light intensity of the radiated light in a state where the phases of the radiated light emitted from each light emitting portion are aligned with each other, and corresponds to FIG. 17 in the third embodiment. [Figure 24] FIG. 11 is a top view schematically illustrating a part of an optical phased array and an optoelectric converter provided on a substrate in an optical waveguide structure in a fourth embodiment, and corresponds to FIG. 10 . [Figure 25] 25 is a cross-sectional view schematically showing the XXV-XXV cross section of FIG. 24 in the fourth embodiment, and corresponds to FIG. 13. FIG. [Figure 26] FIG. 11 is a top view schematically illustrating a part of an optical phased array and a plurality of photoelectric converters provided on a substrate in an optical waveguide structure in a fifth embodiment, and corresponds to FIG. 10 . [Figure 27] FIG. 11 is a top view schematically illustrating a part of an optical phased array, an optoelectronic converter, and a light-receiving waveguide provided on a substrate in the optical waveguide structure in the sixth embodiment, and corresponds to FIG. 10 . [Figure 28] FIG. 11 is a top view schematically illustrating a part of an optical phased array, an optoelectronic converter, and a light-receiving waveguide provided on a substrate in the optical waveguide structure in the seventh embodiment, and corresponds to FIG. 10 . [Figure 29] FIG. 11 is a top view schematically illustrating a part of an optical phased array and an optoelectric converter provided on a substrate in an optical waveguide structure in the eighth embodiment, and corresponds to FIG. 10 . [Figure 30] FIG. 11 is a top view schematically illustrating a part of an optical phased array and an optoelectric converter provided on a substrate in an optical waveguide structure in the ninth embodiment, and corresponds to FIG. 10 . [Figure 31]FIG. 11 is a top view schematically illustrating a part of an optical phased array and an optoelectric converter provided on a substrate in an optical waveguide structure according to another embodiment, and corresponds to FIG. 10 . DETAILED DESCRIPTION OF THE INVENTION

[0013] (Explanation of optical phased array) The optical waveguide structure 10 described in each embodiment below includes an optical phased array, and therefore, the following description will focus on a general optical phased array 70. Note that the optical phased array, i.e., the Optical Phased Array, may be abbreviated as OPA.

[0014] As shown in Fig. 1, the optical phased array 70 is a device that can control the direction and shape of a beam BM emitted from the optical phased array 70 without using a mechanical mechanism. The optical phased array 70 includes a light input unit 71, a light distribution unit 72 connected to the light input unit 71, multiple waveguides 73 connected to the light distribution unit 72 and arranged in parallel with each other, multiple phase adjusters 74, and multiple optical antenna units 75. The phase adjuster 74 is provided midway through each of the multiple waveguides 73 and adjusts the phase of guided light propagating through the waveguides 73. The multiple optical antenna units 75 are provided at the end portions of the multiple waveguides 73, respectively, and emit guided light from the waveguides 73.

[0015] The light incident portion 71, the light distribution portion 72, the plurality of waveguides 73, the plurality of phase adjusters 74, and the plurality of optical antenna portions 75 are formed, for example, by being stacked on a Si substrate (not shown), where "Si" stands for silicon.

[0016] For example, light emitted from a light source 76 such as an infrared laser light source enters a light input unit 71 of the optical phased array 70, and the incident light is distributed to each waveguide 73 by an optical distributor 72. The phases of the guided light, which is light distributed by the optical distributor 72 and propagates to each waveguide 73, are adjusted by respective phase adjusters 74. The phase-adjusted guided light travels through each waveguide 73 toward an optical antenna unit 75 and is output from each optical antenna unit 75 to the outside of the optical phased array 70.

[0017] The optical phased array 70 can form a beam BM formed by light waves WB emitted from each optical antenna unit 75 in any direction by regularly controlling the phase of the guided light propagating through each waveguide 73 with a phase adjuster 74.

[0018] Here, for example, if the phase of the guided light is not controlled at all by the phase adjuster 74 and the guided light is emitted from each optical antenna unit 75, a coherent beam BM is not formed, as shown in Figures 2 and 3. This is because the phase of the guided light propagating through each waveguide varies irregularly due to processing errors, component variations, and the like during the manufacture of the optical phased array 70. Note that the arrow A0 in Figure 2 and Figure 4 (described later) indicates the 0° azimuth shown on the horizontal axis in Figure 3 and Figure 5 (described later).

[0019] Therefore, as a prerequisite for using the optical phased array 70, phase correction is required to eliminate variations in the initial phase of the guided light due to processing errors, component variations, and the like during the manufacture of the optical phased array 70. The initial phase of the guided light is the phase of the guided light before being adjusted by the phase adjuster 74. When this phase correction is performed and the phases of the output light beams emitted from the optical antenna units 75 are aligned with each other, a single unified beam BM is formed in an azimuth of 0°, as shown in FIGS.

[0020] For example, the following first reference example is considered as a configuration for performing the above-described phase correction. In this first reference example, as shown in FIGS. 2 and 4, an infrared camera 77 is provided separately from a chip including an optical phased array 70. The infrared camera 77 is disposed at a 0° azimuth with respect to the optical phased array 70 so as to be able to detect the light emitted from the multiple optical antenna units 75 from the 0° azimuth. While the light emitted from the multiple optical antenna units 75 is monitored by the infrared camera 77, the phase of the guided light is adjusted by each phase adjuster 74 so that the light intensity P0 at the 0° azimuth is maximized, as shown in FIG. 5. As a result of this adjustment, one beam BM is formed at the 0° azimuth, as shown in FIG. 4, and phase correction is completed.

[0021] In the above-described first reference example, although it is possible to perform phase correction, it is necessary to provide an infrared camera 77 separately from the chip including the optical phased array 70, which makes the entire device for performing phase correction large-scale. Therefore, there is a demand for technology that can monitor the phase of guided light in each waveguide 73 within the chip including the optical phased array 70. The following second reference example is considered to be a technology that meets this demand.

[0022] 6 and 7 , in the second reference example, a guided light acquiring unit 80, a relay waveguide 81, and a photodiode 82 are provided between each of the waveguides 73 of the optical phased array 70. The guided light acquiring unit 80, the relay waveguide 81, the photodiode 82, and the optical phased array 70 are formed on a common Si substrate 83. Light enters each of the waveguides 73 of the optical phased array 70 from the optical distribution unit 72 as indicated by the arrows Ai.

[0023] 7 and 8, the waveguide 73 is shown only by the core portion of the waveguide 73, and the clad layer around the core portion is not shown. This method of omitting the clad layer is also used for the relay waveguide 81 and the optical coupling waveguide 801, which will be described later.

[0024] The guided light acquiring unit 80 has a pair of optical coupling waveguides 801, a pair of reflectors 802, and a multiplexer 803. The pair of optical coupling waveguides 801 are arranged so as to be optically coupled to one and the other of a pair of waveguides 73 that sandwich the guided light acquiring unit 80. Therefore, in each of the pair of waveguides 73, a portion of the guided light that has passed through the phase adjuster 74 and is about to reach the optical antenna unit 75 moves from the waveguide 73 to the optical coupling waveguide 801, as shown by arrow A1.

[0025] The guided light that has moved to optical coupling waveguide 801 is reflected by reflector 802 as shown by arrow A2, and is multiplexed by multiplexer 803 as shown by arrow A3. Furthermore, the light multiplexed by multiplexer 803 passes from multiplexer 803 through relay waveguide 81 as shown by arrow A4 and is input to photodiode 82. In phase correction of the guided light, the phase of the guided light is adjusted by each phase adjuster 74 so that the output of photodiode 82, which corresponds to the optical intensity of the input light input to photodiode 82, is maximized in each photodiode 82. As a result of this adjustment, one beam BM is formed in the 0° azimuth, as shown by the solid line in FIG. 6, and phase correction is completed.

[0026] 7, since the guided light acquiring units 80 and the like are provided between the waveguides 73, the pitch P1 of the waveguides 73 is larger than the size of the guided light acquiring units 80. Furthermore, since the guided light acquiring units 80 include the reflectors 802 and the multiplexers 803, the size of the guided light acquiring units 80 is large.

[0027] Therefore, in the second reference example, the guided light acquiring unit 80 prevents the pitch P1 of the waveguides 73 from being narrowed. That is, the second reference example has the disadvantage that the narrowing of the pitch of the waveguides 73 is limited. The beam scanning range θ over which the beam BM can be scanned becomes wider as the pitch of the optical antenna unit 75, which is the same as the pitch P1 of the waveguides 73, becomes smaller. Therefore, in the second reference example in which the narrowing of the pitch of the waveguides 73 is limited, the beam scanning range θ is limited due to the provision of the guided light acquiring unit 80 and the like between the waveguides 73.

[0028] Note that the beam BM indicated by the two-dot chain line in Fig. 6 represents the beam BM scanned in a direction other than the 0° azimuth. Also, in Fig. 7, for the sake of simplicity, the many waveguides 73 shown in Fig. 6 are reduced to three.

[0029] 8, the optical antenna unit 75 in the second reference example has a plurality of light output sections 30 that are lined up along each waveguide 73 and cause light to radiate from the waveguide 73. Each of the plurality of light output sections 30 is composed of a first light output component 30a that configures a portion of the core of the waveguide 73 in the longitudinal direction of the waveguide 73, and a second light output component 30b that is a diffraction grating adjacent to the first light output component 30a.

[0030] Therefore, the first light-emitting component 30a and the second light-emitting component 30b form a pair to constitute the light-emitting component 30, and the multiple second light-emitting components 30b are arranged side by side along the waveguide 73 to which the corresponding light-emitting component 30 is provided. Specifically, each of the multiple second light-emitting components 30b is arranged adjacent to the first light-emitting component 30a so as to diffract and emit light that leaks out from the first light-emitting component 30a. Therefore, the guided light propagating into the waveguide 73 as indicated by arrow A5 is emitted from each of the multiple light-emitting components 30 to the outside of the waveguide 73 as indicated by arrow A6. Therefore, the 0° orientation is on the front side of the paper in FIG. 7.

[0031] The first light-emitting component 30a may be made of, for example, Si, and the second light-emitting component 30b, which is a diffraction grating, may be made of, for example, SiN. Here, "SiN" stands for silicon nitride. Also, in FIG. 7, the waveguides 73, 801, and 81 and the second light-emitting component 30b are hatched for clarity. The longitudinal direction of the waveguide 73 coincides with the first direction D1 in FIGS. 7 and 8.

[0032] The optical waveguide structure 10 including the optical phased array 18 of each embodiment described below in this disclosure is configured in consideration of the above-mentioned disadvantage of the second reference example, in that there is a restriction on narrowing the pitch of the waveguides 73.

[0033] Hereinafter, each embodiment will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

[0034] (First embodiment) 9 and 10, the optical waveguide structure 10 of this embodiment includes a substrate 12, an optoelectronic converter 16, and an optical phased array 18. The optoelectronic converter 16 and the optical phased array 18 are formed on the substrate 12 by silicon photonics technology, and the optical waveguide structure 10 is configured as a single optical integrated chip.

[0035] 9 to 11 are sometimes used to represent the directions in the optical waveguide structure 10. The first direction D1, the second direction D2, and the third direction D3 intersect with each other, or more precisely, are perpendicular to each other. In addition, in FIG. 10 and subsequent figures corresponding to FIG. 10, the cladding layer 13 shown in FIG. 11 is omitted, and therefore the waveguide 22 of the optical phased array 18 is illustrated only by the core 221 that constitutes the waveguide 22.

[0036] The substrate 12 is made of, for example, silicon, i.e., Si, and is formed in the shape of a rectangular flat plate extending in the first direction D1 and the second direction D2. An optoelectronic converter 16 and an optical phased array 18 are formed on this substrate 12. In other words, the optoelectronic converter 16 and the optical phased array 18 are arranged on one side of the substrate 12 in the third direction D3, and are configured to be integrated with the substrate 12.

[0037] 11, the optical waveguide structure 10 has a laminated structure including a substrate 12, a lower cladding layer 131, an upper cladding layer 132, and a core layer 14. The lower cladding layer 131 and the upper cladding layer 132 are made of, for example, silicon oxide, i.e., SiO2, and the core layer 14 is made of, for example, Si. Therefore, for example, the multiple waveguides 22 included in the optical phased array 18 are made of the same material.

[0038] In the laminated structure of the optical waveguide structure 10, the lower cladding layer 131 is laminated on one side in the third direction D3 with respect to the substrate 12, and the core layer 14 is laminated on one side in the third direction D3 with respect to a portion of the lower cladding layer 131. The upper cladding layer 132 is laminated on one side in the third direction D3 with respect to the lower cladding layer 131, and is also laminated on one side in the third direction D3 with respect to the core layer 14 so as to sandwich the core layer 14 between the upper cladding layer 132 and the lower cladding layer 131. In the description of this embodiment, the lower cladding layer 131 and the upper cladding layer 132 may be collectively referred to as cladding layers 13.

[0039] As shown in Figures 9 and 10, the optical phased array 18 includes a light input unit 19, a light distribution unit 20, a plurality of waveguides 22, a plurality of phase adjusters 24, a plurality of optical antenna units 26, and a plurality of light radiating units 34.

[0040] The light entrance section 19, the light distribution section 20, and the plurality of waveguides 22 are configured by the core layer 14 in Fig. 11 and a portion of the cladding layer 13 that surrounds the core layer 14. For example, as shown in Fig. 11, each of the plurality of waveguides 22 is configured by a core portion 221 formed in the core layer 14 corresponding to the waveguide 22, and a cladding portion 222 in the cladding layer 13 that surrounds the core portion 221.

[0041] 9 to 11 , the light incident unit 19 is a portion of the optical phased array 18 into which light emitted by a light source 76, such as an infrared laser light source, is incident. The light distribution unit 20 is disposed on one side of the light incident unit 19 in the first direction D1, and on the other side of each of the multiple waveguides 22 in the first direction D1. In other words, the light distribution unit 20 is disposed between the light incident unit 19 and the multiple waveguides 22. The light incident unit 19 and the multiple waveguides 22 are each connected to the light distribution unit 20. Due to this connection relationship, the light distribution unit 20 distributes the incident light incident on the light incident unit 19 to each of the multiple waveguides 22, as shown by arrows Ai.

[0042] Each of the plurality of waveguides 22 propagates light incident from the light distribution unit 20. The light propagating through the waveguide 22 may be referred to as guided light 22a. The plurality of waveguides 22 each extend in a first direction D1. More specifically, the plurality of waveguides 22 each extend linearly along the first direction D1 in parallel with one another. For example, in this embodiment, the plurality of waveguides 22 are formed to have the same shape.

[0043] The cross-sectional shape of the core portion 221 of the waveguide 22 shown in a cross section perpendicular to the first direction D1, for example, the cross-sectional shape of the core portion 221 shown in Fig. 11, is rectangular. For example, the thickness dimension tc in the third direction D3 of the cross-sectional shape of the core portion 221 is "tc = 0.21 µm," and the width dimension Wc in the second direction D2 is "Wc = 0.5 µm" except for a core width changing portion 341 described below.

[0044] The plurality of waveguides 22 are arranged side by side at a uniform pitch Pd in ​​the second direction D2. That is, the pitch Pd of the waveguides 22 is uniform, and the mutual spacing between any of the plurality of waveguides 22 is the same. For example, the pitch Pd of the waveguides 22 in this embodiment is set to "Pd=1.5 μm."

[0045] The multiple phase adjusters 24 are provided on the substrate 12 for each of the multiple waveguides 22. Specifically, one phase adjuster 24 is provided for each waveguide 22. Therefore, the optical phased array 18 has the same number of phase adjusters 24 as the number of waveguides 22.

[0046] Each of the multiple phase adjusters 24 controls the phase of the guided light 22a propagating through the waveguide 22 in which the phase adjuster 24 is provided. For example, the phase adjuster 24 changes the refractive index of the material constituting the adjusted portion of the waveguide 22 in which the phase adjuster 24 is arranged, by the electro-optic effect or the thermo-optic effect, and the change in the refractive index changes the phase of the guided light 22a passing through the adjusted portion.

[0047] When the phase adjuster 24 is configured to utilize the electro-optic effect, the phase adjuster 24 has a pair of electrodes arranged on either side of the waveguide 22, and the phase of the guided light 22a is changed by applying a voltage between the pair of electrodes. When the phase adjuster 24 is configured to utilize the thermo-optic effect, the phase adjuster 24 has a heater that can heat an adjusted portion of the waveguide 22 by passing electricity through it, and the phase of the guided light 22a is changed by heating the adjusted portion with the heater.

[0048] The optical antenna units 26 are provided on the substrate 12 for each of the waveguides 22. Specifically, one optical antenna unit 26 is provided for each waveguide 22. Therefore, the optical phased array 18 has the same number of optical antenna units 26 as the number of waveguides 22.

[0049] Each of the optical antenna units 26 radiates guided light 22a propagating through the waveguide 22 in which the optical antenna unit 26 is provided, from the waveguide 22. In detail, the optical antenna unit 26 is disposed on the opposite side of the phase adjuster 24 from the optical distribution unit 20 side, in other words, on one side of the phase adjuster 24 in the first direction D1, and therefore radiates guided light 22a propagating through the waveguide 22 after passing through the phase adjuster 24, from the waveguide 22.

[0050] Specifically, each of the plurality of optical antenna units 26 is configured as shown in Figures 8 and 10. That is, in this embodiment, as in the above-described second reference example, each of the plurality of optical antenna units 26 has a plurality of light output units 30 for each waveguide 22 that are lined up along the waveguide 22 and cause light to radiate from the waveguide 22.

[0051] Each of the plurality of light output sections 30 includes a first light output component 30a that constitutes a portion of the core 221 of the waveguide 22 in the first direction D1, and a second light output component 30b that is a diffraction grating adjacent to the first light output component 30a. The second light output component 30b is made of, for example, silicon nitride (SiN). As shown in FIGS. 8, 10, and 11, the second light output component 30b is disposed on one side of the first light output component 30a in the third direction D3 and is included in the upper cladding layer 132.

[0052] Therefore, the first light output component 30a and the second light output component 30b form a pair to constitute the light output component 30, and the multiple second light output components 30b are arranged side by side along the waveguide 22 to which the light output component 30 to which it belongs is provided. In detail, each of the multiple second light output components 30b is arranged adjacent to the first light output component 30a on one side of the third direction D3 so as to diffract and output the light that has leaked out from the first light output component 30a. In other words, each of the multiple second light output components 30b is arranged close to the first light output component 30a so as to output the guided light 22a from the first light output component 30a to the outside of the waveguide 22.

[0053] Therefore, the guided light 22a propagating through the waveguide 22 is output to the outside from each of the plurality of light output sections 30 as indicated by arrow A6 in Fig. 8. That is, in this embodiment, the antenna section radiation direction Dan, which is the direction in which the optical antenna section 26 radiates the guided light 22a propagating through the waveguide 22 to the outside, is along the third direction D3 as shown in Fig. 11. Note that in Fig. 10 and subsequent figures corresponding to Fig. 10, the waveguide 22 and the second light output section 30b are hatched for ease of understanding.

[0054] The plurality of light radiating units 34 are provided on the substrate 12 for each of the plurality of waveguides 22. Specifically, one light radiating unit 34 is provided for each of the waveguides 22. Therefore, the optical phased array 18 has the same number of light radiating units 34 as the number of waveguides 22. In the description of the present embodiment, all of the light radiating units 34 included in the optical phased array 18 may be collectively referred to as a light radiating unit group 33. For example, the plurality of light radiating units 34 are provided at positions aligned with one another in the first direction D1.

[0055] Furthermore, each of the plurality of light radiating sections 34 is disposed between the phase adjuster 24 and the optical antenna section 26. With this arrangement, the light radiating section 34 radiates a portion of the guided light 22a, which passes through the phase adjuster 24 and propagates through the waveguide 22, from the waveguide 22 in a direction different from the antenna section radiation direction Dan in Fig. 11 before the guided light 22a reaches the optical antenna section 26. For example, in this embodiment, each of the plurality of light radiating sections 34 radiates a portion of the guided light 22a from the light radiating section 34 to one side and the other side of the second direction D2 as radiated light.

[0056] 10, 12, and 13, each of the plurality of waveguides 22 has a core width varying portion 341 in which the width dimension Wc, which is the core width of the core portion 221 of the waveguide 22 in the second direction D2, varies locally. In this embodiment, the core width of the core portion 221 of the waveguide 22 is locally narrowed at the core width varying portion 341. Each of the plurality of light emitting portions 34 is constituted by the core width varying portion 341.

[0057] In detail, a groove 341a is formed in the core width changing section 341 of the waveguide 22 so as to be cut into the core portion 221 from one side in the second direction D2 and extend through to the third direction D3. Due to the formation of this groove 341a, the width dimension Wc of the core portion 221 in the core width changing section 341 is smaller than the width dimension Wc of the core portion 221 at a portion of the waveguide 22 adjacent to the core width changing section 341.

[0058] 12, the groove 341a in this embodiment has a rectangular cross-sectional shape, and the groove width Wm of the groove 341a in the first direction D1 is set to "Wm = 0.1 μm," and the groove depth Hm of the groove 341a in the second direction D2 is also set to "Hm = 0.1 μm." The larger the groove 341a, the greater the amount of light emitted from the light emitting portion 34, and therefore the amount of light emitted from the light emitting portion 34 is adjusted by the size of the groove 341a.

[0059] In the optical phased array 18 configured as described above, if the phases of the radiated light, which is the guided light 22a radiated from each light radiating unit 34, are not uniform, the radiated light from each light radiating unit 34 will be dispersed as indicated by arrow A7, and no beam will be formed, as shown in Figures 14 and 15. In contrast, if the phases of the radiated light from each light radiating unit 34 are uniform, for example, if the phases of the radiated light are in phase with each other, then a radiated beam Ba composed of the radiated light from each light radiating unit 34 will be formed in a specific direction, as shown in Figures 16 and 17.

[0060] The beam forming direction Dba (see FIG. 10), which is the direction of this radiation beam Ba, changes depending on, for example, the wavelength of the guided light 22a propagating through the waveguide 22. The beam forming direction Dba, i.e., the direction of the radiation beam Ba, is information necessary for determining the relative positioning of the photoelectric converter 16 with respect to the light emitting portion group 33, as will be described later. Therefore, in this embodiment, the wavelength of the light emitted by the light source 76 is determined in advance, and then the beam forming direction Dba is calculated by computer simulation.

[0061] 16, two radiation beams Ba traveling from the light emitting portion group 33 to one side in the second direction D2 are represented by arrows, but two radiation beams Ba are also formed on the other side in the second direction D2 relative to the light emitting portion group 33, similar to the one side. Also, arrow B0 in Fig. 14 indicates the 0° azimuth shown on the horizontal axis in Figs. 15 and 17.

[0062] 10 and 17, for example, in this embodiment, one of the multiple radiation beams Ba is formed in a direction along the beam axis Lba in Fig. 10 when viewed in the direction along the third direction D3. That is, when viewed in the direction along the third direction D3, the single radiation beam Ba is formed at an angle α of 30.5° with respect to the second direction D2 so as to be positioned towards one side of the first direction D1 towards one side of the second direction D2 with respect to the center 33a of the light emitting portion group 33.

[0063] The radiated light emitted from the light radiating portions 34 provided in each of the plurality of waveguides 22 passes through other waveguides 22 arranged side by side with respect to the waveguide 22 from which it originates, and travels to one side and the other side in the second direction D2. When the radiated light from each light radiating portion 34 is in phase with each other, the radiated light that has passed through the other waveguides 22 and the radiated light that has not will combine to form a radiated beam Ba.

[0064] 10 and 13, the optoelectronic converter 16 is disposed on one side in the second direction D2 with respect to all of the waveguides 22 included in the optical phased array 18. That is, the optoelectronic converter 16 is disposed on one side in the second direction D2 with respect to all of the light emitting units 34 included in the optical phased array 18.

[0065] The photoelectric converter 16 is a photodetector that outputs an electrical signal corresponding to the intensity of light incident on the photoelectric converter 16. The electrical signal output from the photoelectric converter 16 is guided to the outside of the optical waveguide structure 10 by a connection terminal (not shown) provided on the substrate 12. The photoelectric converter 16 is stacked on one side in the third direction D3 with respect to a base portion 141, which is a part of the core layer 14, and is surrounded by the base portion 141 and the upper clad layer 132.

[0066] Specifically, the photoelectric converter 16 of this embodiment is a photodiode made of germanium, i.e., Ge. The greater the intensity of light incident on the photoelectric converter 16, the greater the output of the photoelectric converter 16 as an electrical signal. "PD" in FIG. 10 is an abbreviation for photodiode.

[0067] 10, the position of the photoelectric converter 16 is determined so that the radiation beam Ba enters the photoelectric converter 16 when the phases of the radiation light emitted from each light emitting portion 34 are aligned with each other. More specifically, since a plurality of radiation beams Ba are formed, the position of the photoelectric converter 16 is determined so that at least one of the plurality of radiation beams Ba enters the photoelectric converter 16.

[0068] For example, in this embodiment, as described above, one of the multiple radiation beams Ba is formed to extend along the beam axis Lba in FIG. 10 when viewed in the third direction D3. Therefore, when viewed in the third direction D3, the photoelectric converter 16 is disposed on an extension of the beam axis Lba. For example, the photoelectric converter 16 is disposed on one side in the first direction D1 and one side in the second direction D2 with respect to the center 33a of the light emitting portion group 33. Note that the beam axis Lba in FIG. 10 extends through the center 33a of the light emitting portion group 33 in the beam forming direction Dba that is inclined by an angle α with respect to the second direction D2 so as to be shifted toward one side of the first direction D1 as it approaches one side of the second direction D2.

[0069] 9 and 10 , in the optical waveguide structure 10 configured as described above, light emitted from the light source 76 is incident on the light incident unit 19 of the optical phased array 18, and the incident light is distributed to each waveguide 22 by the optical distribution unit 20. The phase of guided light 22a, which is light distributed by the optical distribution unit 20 and propagates to each waveguide 22, is adjusted by each phase adjuster 24, and the phase-adjusted guided light 22a travels through each waveguide 22 toward the optical antenna unit 26 and is emitted from each optical antenna unit 26 to the outside of the optical waveguide structure 10.

[0070] However, since the optical phased array 18 of this embodiment is provided with the light radiating unit 34, in each waveguide 22, a portion of the phase-adjusted guided light 22a is emitted as radiated light from the light radiating unit 34 before reaching the optical antenna unit 26. For example, in this embodiment, the amount of radiated light emitted from the light radiating unit 34 is about 3% of the amount of guided light 22a output from the phase adjuster 24.

[0071] Furthermore, the optical phased array 18 of this embodiment can scan the beam BM in the same way as the optical phased array 70 in Fig. 1. That is, the optical phased array 18 of this embodiment can form the beam BM, which is formed by light emitted from each optical antenna unit 26, in any direction by regularly controlling the phase of the guided light 22a propagating in each waveguide 22 with the phase adjuster 24.

[0072] In this embodiment, the light emitted from each light emitting portion 34 is used to perform phase correction to eliminate variations in the initial phase of the guided light 22a in each waveguide 22. Specifically, in the phase correction of the guided light 22a, the phase of the guided light 22a is adjusted by each phase adjuster 24 so that the output of the photoelectric converter 16 becomes maximum within an adjustable range.

[0073] As described above, according to the present embodiment, as shown in FIGS. 10 and 11 , a light radiating unit 34 is provided on the substrate 12 for each of the plurality of waveguides 22. The light radiating unit 34 radiates, as radiated light, a portion of the guided light 22a that passes through the phase adjuster 24 and propagates to the waveguide 22 from the waveguide 22 in a direction different from the antenna unit radiation direction Dan in FIG. 11 . The optoelectronic converter 16 is provided on the substrate 12 and disposed on one side of all the light radiating units 34 of the optical phased array 18 in the second direction D2. The position of the optoelectronic converter 16 is determined so that the radiated beam Ba enters the optoelectronic converter 16 when the phases of the radiated light radiated from the respective light radiating units 34 of the plurality of waveguides 22 are aligned with each other.

[0074] As a result, a portion of the guided light 22a propagating through each waveguide 22 is emitted as radiated light from each of the plurality of light emitting portions 34, and when the phases of the radiated light are aligned with each other, the radiated light becomes a radiated beam Ba and is incident on the photoelectric converter 16. Therefore, the photoelectric converter 16 can obtain the function of acquiring the guided light 22a in order to perform phase correction to reduce phase variations of the guided light 22a in the plurality of waveguides 22. Furthermore, since the photoelectric converter 16 is provided on the same substrate 12 as the plurality of waveguides 22, it is possible to provide a chip having the plurality of waveguides 22 with the function of acquiring the guided light 22a for phase correction.

[0075] Furthermore, the optoelectronic converters 16 are arranged on one side in the second direction D2 with respect to all of the light radiating units 34 of the optical phased array 18, and therefore the arrangement of the waveguides 22 is not prevented from narrowing the pitch. For example, compared to a configuration in which various elements such as the optoelectronic converters 16 are arranged between the waveguides 22 that propagate the guided light 22a, specifically the configuration of the second reference example described above, it can be said that the arrangement of the waveguides 22 is less likely to be prevented from narrowing the pitch.

[0076] (1) Furthermore, according to this embodiment, as shown in Figures 10 and 12, each of the multiple waveguides 22 has a core width varying portion 341 in which the width dimension Wc, which is the core width of the core portion 221 of the waveguide 22 in the second direction D2, varies locally. The multiple light radiating portions 34 are each formed by the core width varying portion 341. Therefore, since the light radiating portion 34 can be formed depending on the shape of the waveguide 22, there is an advantage in that the light radiating portion 34 can be easily provided in the manufacture of the optical waveguide structure 10.

[0077] (2) Furthermore, according to this embodiment, the core width varying portion 341 included in each of the plurality of waveguides 22 is a portion where the core width of the core portion 221 of the waveguide 22 is locally narrowed. Therefore, compared to the case where the core width varying portion 341 is a portion of the waveguide 22 where the core width is locally widened in the second direction D2, for example, there is an advantage in that it is easier to achieve a narrow pitch for arranging the waveguides 22.

[0078] (Second embodiment) Next, a second embodiment will be described. In this embodiment, differences from the first embodiment will be mainly described. Furthermore, parts that are the same as or equivalent to the first embodiment will be omitted or simplified. This also applies to the following embodiments.

[0079] 18 and 19 , in the present embodiment, as in the first embodiment, the core width changing portion 341 included in each of the plurality of waveguides 22 is a portion where the width dimension Wc, which is the core width of the waveguide 22, changes locally. The plurality of light emitting portions 34 are each formed by the core width changing portion 341.

[0080] However, in this embodiment, no groove 341a (see FIG. 12) is formed in the core width changing portion 341. Instead, in this embodiment, a protrusion 341b protruding to one side in the second direction D2 is formed in the core width changing portion 341. Therefore, the core width changing portion 341 that each of the multiple waveguides 22 has is a portion where the core width of the waveguide 22 is locally expanded.

[0081] Except for the points described above, this embodiment is the same as the first embodiment. In this embodiment, the same effects as those of the first embodiment can be obtained from the configuration common to the first embodiment.

[0082] (Third embodiment) Next, a third embodiment will be described, focusing on the differences from the first embodiment.

[0083] 20 to 22, in this embodiment, the structure of the light radiating portion 34 is different from that in the first embodiment, and the groove 341a in Fig. 12 is not formed in the waveguide 22. Therefore, the light radiating portion 34 of this embodiment does not have the core width changing portion 341 in Fig. 12.

[0084] Specifically, each of the multiple light radiating sections 34 of this embodiment has a radiating section 342 and a closely-located section 343. The radiating section 342 forms a part of the core section 221 of the waveguide 22 in the first direction D1. The closely-located section 343 is disposed offset to one side in the second direction D2 with respect to the radiating section 342. Specifically, the closely-located section 343 is disposed next to the radiating section 342 with a small gap therebetween on one side in the second direction D2.

[0085] In detail, each of the multiple closely spaced portions 343 provided for each waveguide 22 is formed to be stacked on one side of the substrate 12 in the third direction D3, similar to the waveguide 22. Each of the multiple closely spaced portions 343 is made of the same material as the core portions 221 of the multiple waveguides 22, and is included in the same core layer 14 as the core portions 221 of the waveguides 22 in the stacked structure of the optical waveguide structure 10. In other words, the closely spaced portions 343 are made of the same Si as the core portions 221, and have the same thickness dimension tc as the core portions 221.

[0086] Furthermore, in each of the plurality of light emitting sections 34, the closely disposed section 343 is disposed adjacent to the emitting section 342 on one side in the second direction D2 so as to diffract and emit light that has leaked out from the emitting section 342. In other words, the closely disposed section 343 is disposed adjacent to the emitting section 342 so as to emit a part of the guided light 22a from the emitting section 342 to the outside of the waveguide 22.

[0087] The closely spaced portion 343 has a rectangular parallelepiped shape. For example, a first width W1, which is the width of the closely spaced portion 343 in the first direction D1, and a second width W2, which is the width of the closely spaced portion 343 in the second direction D2, are "W1 = W2 = 0.3 μm," and a mutual distance CD between the closely spaced portion 343 and the radiating portion 342 in the second direction D2 is "CD = 0.1 μm."

[0088] As described above, the closely spaced portion 343 of the light radiating portion 34 is positioned offset in the second direction D2 relative to the radiation component portion 342, so that in this embodiment, each of the multiple light radiating portions 34 radiates a portion of the guided light 22a from the light radiating portion 34 to one side and the other side of the second direction D2.

[0089] (1) As described above, according to this embodiment, each of the light radiating portions 34 has a radiating component 342 included in the core portion 221 of the waveguide 22, and a closely-arranged portion 343. The closely-arranged portion 343 is provided close to the radiating component 342 so as to emit a portion of the guided light 22a from the radiating component 342, and is arranged offset in the second direction D2 with respect to the radiating component 342.

[0090] As a result, the diffraction structure for radiating a portion of the guided light 22a from the waveguide 22 to one side and the other side in the second direction D2 can be formed apart from the waveguide 22, rather than being formed directly on the waveguide 22. Therefore, even if the dimensional processing accuracy of the core layer 14 is low, it is possible to design the amount of light used for phase correction to be smaller than in, for example, the first embodiment. If the amount of light used for phase correction is smaller, the amount of light emitted from the optical antenna portion 26 can be increased accordingly.

[0091] 23, in this embodiment, the radiated beam Ba formed by the radiated light from each light radiator 34 is formed in the same manner as in the first embodiment, and the beam formation direction Dba, which is the direction of the radiated beam Ba, is the same as in, for example, the first embodiment. Therefore, in this embodiment, the relative arrangement of the photoelectric converter 16 with respect to the light radiator group 33 is the same as in the first embodiment. However, the light intensity of the radiated beam Ba in this embodiment is lower than in the first embodiment. The direction constituting the horizontal axis in the coordinate system of FIG. 23 is the same as the direction constituting the horizontal axis in the coordinate system of FIG. 17.

[0092] (2) Furthermore, according to this embodiment, the multiple closely spaced portions 343 are each made of the same material as the core portions 221 of the multiple waveguides 22, and are included in the same core layer 14 as the core portions 221 of the waveguides 22 in the laminated structure of the optical waveguide structure 10. Therefore, it is possible to easily form the closely spaced portions 343 while suppressing an increase in manufacturing steps due to the provision of the closely spaced portions 343.

[0093] Except for the points described above, this embodiment is the same as the first embodiment. In this embodiment, the same effects as those of the first embodiment can be obtained from the configuration common to the first embodiment.

[0094] (Fourth embodiment) Next, a fourth embodiment will be described, focusing on the differences from the third embodiment.

[0095] As shown in Figures 24 and 25, in this embodiment, each of the multiple light emitting sections 34 has a emitting component 342 and a closely-located section 343, but the location of the closely-located section 343 is different from that in the third embodiment.

[0096] Specifically, in this embodiment, the closely-arranged portion 343 in each of the multiple light emitting portions 34 is arranged to be shifted to the other side in the second direction D2 with respect to the radiating component 342. The closely-arranged portion 343 is not included in the core layer 14, and is arranged away from the radiating component 342 on one side in the third direction D3 with a small gap therebetween, and a portion of the closely-arranged portion 343 overlaps a portion of the radiating component 342 on one side in the third direction D3.

[0097] Furthermore, the closely arranged portion 343 may be made of the same material as the core portion 221 of the waveguide 22, but in this embodiment it is made of a different material from the core portion 221, for example, SiN.

[0098] In this embodiment, the closely spaced portion 343 of the light radiating portion 34 is also positioned offset in the second direction D2 relative to the radiation component portion 342, so that each of the multiple light radiating portions 34 radiates a portion of the guided light 22a from that light radiating portion 34 to one side and the other side of the second direction D2.

[0099] Except for the points described above, this embodiment is the same as the third embodiment. In this embodiment, the same effects as those of the third embodiment can be obtained from the configuration common to the third embodiment.

[0100] (Fifth embodiment) Next, a fifth embodiment will be described, focusing on the differences from the first embodiment.

[0101] 26, in this embodiment, two photoelectric converters 16 are provided on the substrate 12. One of the two photoelectric converters 16 is referred to as a first photoelectric converter 161, and the other is referred to as a second photoelectric converter 162. The first and second photoelectric converters 161 and 162 are each the same photodetectors as the photoelectric converter 16 of the first embodiment, and the arrangement of the first and second photoelectric converters 161 and 162 in the third direction D3 is the same as that of the photoelectric converter 16 of the first embodiment.

[0102] The first photoelectric converter 161 is arranged in a different orientation from the orientation in which the second photoelectric converter 162 is arranged, based on the center 33a of the light emitting portion group 33, when viewed in a direction along the third direction D3.

[0103] Specifically, the first photoelectric converter 161 is disposed so as to overlap with a first beam axis L1ba extending through the center 33a of the light emitting unit group 33 when viewed in the third direction D3. The first beam axis L1ba is a straight line along the first radiated beam B1a indicated by an arrow in FIG. 26 . The first radiated beam B1a is one of a plurality of radiated beams Ba formed by the radiated light when the wavelength of the light emitted by the light source 76 is a predetermined first wavelength λ1 and the phases of the radiated light from each light emitting unit 34 are aligned with each other. In this way, the arrangement of the first photoelectric converter 161 is determined corresponding to the case where the wavelength of the light emitted by the light source 76 is the first wavelength λ1.

[0104] The second photoelectric converter 162 is disposed so as to overlap with a second beam axis L2ba that extends through the center 33a of the light emitting unit group 33 when viewed in the third direction D3. The second beam axis L2ba intersects with the first beam axis L1ba and is a straight line along the second radiated beam B2a indicated by the arrow in FIG. 26. The second radiated beam B2a is one of a plurality of radiated beams Ba that are formed by the light emitted by the light source 76 when the wavelength of the light emitted by the light source 76 is a predetermined second wavelength λ2 different from the first wavelength λ1 and the phases of the light emitted from each light emitting unit 34 are aligned with each other. In this way, the arrangement of the second photoelectric converter 162 is determined to correspond to the case where the wavelength of the light emitted by the light source 76 is the second wavelength λ2.

[0105] The orientation and position of the first beam axis L1ba along the first radiation beam B1a can be determined by computer simulation, with the wavelength of the light emitted by the light source 76 predetermined to be a first wavelength λ1. Similarly, the orientation and position of the second beam axis L2ba along the second radiation beam B2a can be determined by computer simulation, with the wavelength of the light emitted by the light source 76 predetermined to be a second wavelength λ2.

[0106] (1) As described above, according to this embodiment, the first photoelectric converter 161 is arranged in an orientation different from the orientation in which the second photoelectric converter 162 is arranged, based on the center 33a of the light emitting portion group 33, when viewed in a direction along the third direction D3.

[0107] If the wavelength of the light emitted by the light source 76 is different, the directions of the radiation beams B1a, B2a formed by the radiation light when the phases of the radiation light from each light emitting portion 34 are aligned will also differ depending on the wavelength. Therefore, in order to deal with the case where the light emitted by the light source 76 is switched to a plurality of different wavelengths and to perform phase correction for each wavelength, the optical waveguide structure 10 can be provided with a function of acquiring the guided light 22a of each waveguide 22.

[0108] Except for the points described above, this embodiment is the same as the first embodiment. In this embodiment, the same effects as those of the first embodiment can be obtained from the configuration common to the first embodiment.

[0109] It should be noted that although this embodiment is a modification based on the first embodiment, it is also possible to combine this embodiment with any of the second to fourth embodiments described above.

[0110] (Sixth embodiment) Next, a sixth embodiment will be described, focusing on the differences from the first embodiment.

[0111] 27, the optical waveguide structure 10 includes a light-receiving waveguide 36 connected to the photoelectric converter 16. The light-receiving waveguide 36 is a waveguide that guides, to the photoelectric converter 16, a radiated beam Ba formed by radiated light from the light emitting portions 34 when the phases of the radiated light are aligned and that is radiated from the light emitting portion group 33. Therefore, when viewed in the third direction D3, the light-receiving waveguide 36 extends from the photoelectric converter 16 toward the center 33a of the light emitting portion group 33.

[0112] For example, the light-receiving waveguide 36 is composed of a core portion formed in the laminate structure of the optical waveguide structure 10 at the same stacking position as the photoelectric converter 16 in the third direction D3, and a cladding portion surrounding the core portion in the cladding layer 13 of Fig. 13. The core portion of the light-receiving waveguide 36 is composed of, for example, Si.

[0113] (1) As described above, according to this embodiment, when viewed in the third direction D3, the light-receiving waveguide 36 extends from the photoelectric converter 16 toward the center 33a of the light emitting portion group 33. Therefore, the light-receiving waveguide 36 is arranged so as to be parallel or approximately parallel to the radiant beam Ba emitted from the light emitting portion group 33.

[0114] Therefore, the radiation beam Ba is guided to the photoelectric converter 16 through the light-receiving waveguide 36, while the disturbance light Nz oriented in a direction intersecting the radiation beam Ba is prevented by the light-receiving waveguide 36 from entering the photoelectric converter 16. As a result, the phase correction described above can be performed with high precision using the radiation beam Ba incident on the photoelectric converter 16.

[0115] Except for the points described above, this embodiment is the same as the first embodiment. In this embodiment, the same effects as those of the first embodiment can be obtained from the configuration common to the first embodiment.

[0116] Although this embodiment is a modification based on the first embodiment, it is also possible to combine this embodiment with any of the second to fifth embodiments described above.

[0117] (Seventh embodiment) Next, a seventh embodiment will be described, focusing on the differences from the sixth embodiment.

[0118] 28, when viewed in the third direction D3, the light-receiving waveguide 36 becomes wider along the extension direction of the light-receiving waveguide 36, i.e., the extension direction of the beam axis Lba, as it moves away from the photoelectric converter 16. In other words, the tip of the light-receiving waveguide 36 on the light emitting portion group 33 side is wider than the base end on the photoelectric converter 16 side.

[0119] (1) As described above, according to this embodiment, when viewed in the third direction D3, the width of the light-receiving waveguide 36 increases as the light-receiving waveguide 36 extends away from the photoelectric converter 16. Therefore, the light-receiving angle at which the light-receiving waveguide 36 can receive light from the light emitting portion group 33 side becomes narrower. In other words, the directivity of the light-receiving waveguide 36 when receiving light from the light emitting portion group 33 side becomes higher. As a result, the phase correction can be performed with higher accuracy than when, for example, the light-receiving waveguide 36 has a shape that extends with a constant width.

[0120] Except for the points described above, this embodiment is the same as the sixth embodiment. In this embodiment, the same effects as those of the sixth embodiment can be obtained from the configuration common to the sixth embodiment.

[0121] (Eighth embodiment) Next, an eighth embodiment will be described. In this embodiment, differences from the first embodiment will be mainly described.

[0122] As shown in Fig. 29, in this embodiment, the locations of the light emitting sections 34 in each of the plurality of waveguides 22 are different from those in the first embodiment. Note that in Fig. 29 and Fig. 30 described later, "..." displayed between adjacent light exit sections 30 means that the plurality of light exit sections 30 are not shown.

[0123] Specifically, the plurality of light radiating portions 34 in this embodiment are each disposed midway along a light exit portion row 30c formed by the plurality of light exit portions 30 for each waveguide 22. For example, in each of the plurality of waveguides 22, the plurality of light exit portions 30 are provided on one side of the light radiating portion 34 in the first direction D1, and the plurality of light exit portions 30 are also provided on the other side of the light radiating portion 34 in the first direction D1.

[0124] Here, each waveguide 22 is actually formed with some tolerance during manufacturing, so that the guided light 22a travels through the waveguide 22 with a slight change in the phase of the guided light 22a.

[0125] In contrast to this, according to this embodiment, as described above, each of the plurality of light emitting portions 34 is disposed midway along the light output portion row 30c formed by the plurality of light output portions 30 for each waveguide 22. As a result, the radiated beam Ba incident on the photoelectric converter 16 from the light emitting portion group 33 is composed of light emitted from a portion of the waveguide 22 that overlaps with the optical antenna portion 26.

[0126] Therefore, compared to when the light radiating portion 34 in each waveguide 22 is disposed on one side or the other side in the first direction D1 of the optical antenna portion 26, it is possible to perform the phase correction so that the phases of the light emitted from each of the optical antenna portions 26 are aligned with high precision. As a result, it is possible to scan the beam BM formed by the light emitted from each optical antenna portion 26 with high precision.

[0127] Except for the points described above, this embodiment is the same as the first embodiment. In this embodiment, the same effects as those of the first embodiment can be obtained from the configuration common to the first embodiment.

[0128] It should be noted that although this embodiment is a modification based on the first embodiment, it is also possible to combine this embodiment with any of the second to seventh embodiments described above.

[0129] (Ninth embodiment) Next, a ninth embodiment will be described, focusing on the differences from the first embodiment.

[0130] As shown in FIG. 30, in this embodiment, the locations of the light radiating portions 34 in each of the plurality of waveguides 22 are different from those in the first embodiment.

[0131] Specifically, the plurality of light radiating portions 34 in this embodiment are each provided on the opposite side of the phase adjuster 24 with respect to the optical antenna portion 26 for each waveguide 22. That is, in each of the plurality of waveguides 22, the light radiating portion 34 is provided on one side of the optical antenna portion 26 in the first direction D1.

[0132] Therefore, the radiation beam Ba for phase correction can be formed using the light that remains without being emitted from the optical antenna portion 26, so that phase correction can be performed without wasting energy.

[0133] Except for the points described above, this embodiment is the same as the first embodiment. In this embodiment, the same effects as those of the first embodiment can be obtained from the configuration common to the first embodiment.

[0134] It should be noted that although this embodiment is a modification based on the first embodiment, it is also possible to combine this embodiment with any of the second to seventh embodiments described above.

[0135] (Other embodiments) (1) In each of the above-described embodiments, three waveguides 22 are provided as shown in FIG. 10, but the number may be two, or four or more.

[0136] (2) In the first embodiment described above, as shown in FIG. 10 , the optoelectronic converters 16 are disposed on one side in the second direction D2 with respect to all of the light radiating units 34 included in the optical phased array 18. However, this is merely an example. For example, the optoelectronic converters 16 may be disposed on the other side in the second direction D2 with respect to all of the light radiating units 34, i.e., on the opposite side from the side on which the grooves 341a of the light radiating units 34 are formed in each waveguide 22. Furthermore, as shown in FIG. 31 , the optoelectronic converters 16 may be disposed on both one side and the other side in the second direction D2 with respect to all of the light radiating units 34. This is because each of the multiple light radiating units 34 radiates a portion of the guided light 22a from the light radiating unit 34 to both one side and the other side in the second direction D2. Even when the photoelectric converters 16 are arranged on the other side in the second direction D2 with respect to all of the light emitting portions 34 as described above, similarly to the first embodiment, the photoelectric converters 16 do not prevent the arrangement of the waveguides 22 from being spaced at a narrower pitch. This is also true when the photoelectric converters 16 are arranged on both one side and the other side in the second direction D2 with respect to all of the light emitting portions 34 as described above.

[0137] (3) In the above-described embodiments, for example, the substrate 12 shown in Fig. 11 is made of Si, the cladding layer 13 is made of SiO2, the core layer 14 is made of Si, and the second light-emitting component 30b is made of SiN, but this is just an example. Each of these components may be made of other materials.

[0138] For example, the cladding layer 13 may be made of any of SiN, SiON, LN, InGaAsP, and InP. The core layer 14 may be made of any of impurity-doped SiO, SiN, SiON, LN, InGaAsP, and InP. However, the refractive index of the core layer 14 must be higher than that of the cladding layer 13, and the second light-emitting component 30b must have a different refractive index from that of the cladding layer 13.

[0139] (4) In each of the above-described embodiments, for example, the photoelectric converter 16 shown in Fig. 11 is made of Ge, but it may be made of a material other than Ge. For example, the material of the photoelectric converter 16 is appropriately selected depending on the wavelength of the guided light 22a propagating through the waveguide 22.

[0140] (5) In each of the above-described embodiments, the antenna unit radiation direction Dan, which is the direction in which each optical antenna unit 26 radiates light to the outside, is a direction along the third direction D3, as shown in Fig. 11, but this is just an example. For example, the optical antenna unit 26 may have a structure different from that shown in Fig. 8 and may be configured to emit light to one side of the first direction D1.

[0141] (6) The present disclosure is not limited to the above-described embodiments and can be implemented in various modifications. Furthermore, the above-described embodiments are not unrelated to each other and can be combined as appropriate, except in cases where the combination is clearly impossible.

[0142] Furthermore, in each of the above embodiments, it goes without saying that the elements constituting the embodiments are not necessarily essential unless they are particularly explicitly stated as essential or are clearly considered essential in principle. Furthermore, in each of the above embodiments, when the numbers, values, amounts, ranges, etc. of the components of the embodiments are mentioned, they are not limited to the specific numbers unless they are particularly explicitly stated as essential or are clearly limited to a specific number in principle. Furthermore, in each of the above embodiments, when the materials, shapes, positional relationships, etc. of the components are mentioned, they are not limited to the materials, shapes, positional relationships, etc. unless they are particularly explicitly stated or are clearly limited to a specific material, shape, positional relationship, etc. in principle.

[0143] (Aspects of the present disclosure) The present disclosure described above can be understood from the following viewpoints, for example. [First viewpoint] An optical waveguide structure, A substrate (12); a plurality of waveguides (22) that are provided on the substrate, extend in a first direction (D1), and are arranged so as to be aligned at a uniform pitch (Pd) in a second direction (D2) perpendicular to the first direction, and through which light propagates; a plurality of phase adjusters (24) provided on the substrate for each of the plurality of waveguides, each of which adjusts the phase of light propagating through the waveguide; a plurality of optical antenna units (26) provided on the substrate in the plurality of waveguides, respectively, for radiating light that passes through the phase adjuster and propagates to the waveguides from the waveguides in an antenna unit radiation direction (Dan); a plurality of light radiating sections (34) provided on the substrate in the plurality of waveguides, each of which radiates a portion of light that passes through the phase adjuster and propagates to the waveguide as radiated light from the waveguide in a direction different from the radiation direction of the antenna section; a photoelectric converter (16, 161, 162) provided on the substrate, arranged on one side or the other side or both sides of the plurality of light emitting units in the second direction, and outputting an electrical signal according to the intensity of incident light; an optical waveguide structure in which the position of the photoelectric converter is determined so that when the phases of the radiation light emitted from each of the plurality of light emitting portions are aligned with each other, a radiation beam (Ba, B1a, B2a) formed by the radiation light is incident on the photoelectric converter. [Second perspective] Each of the plurality of waveguides has a core width varying portion (341) in which the core width (Wc) of the core portion (221) of the waveguide in the second direction varies locally, The optical waveguide structure according to a first aspect, wherein the plurality of light radiating portions are each formed by the core width changing portion. [Third Perspective] Each of the plurality of waveguides has a core width varying portion (341) in which a core width (Wc) of a core portion (221) of the waveguide in the second direction is locally narrowed, The optical waveguide structure according to a first aspect, wherein the plurality of light radiating portions are each formed by the core width changing portion. [Fourth viewpoint] The optical waveguide structure according to a first aspect, wherein the plurality of light radiating portions are each composed of a radiating component (342) included in a core portion (221) of the waveguide, and a closely-located portion (343) that is provided close to the radiating component so as to emit light from the radiating component and is positioned offset in the second direction with respect to the radiating component. [Fifth viewpoint] the closely arranged portions and the plurality of waveguides included in the plurality of light radiating portions are formed to be stacked on the substrate, The optical waveguide structure according to a fourth aspect, wherein each of the plurality of closely spaced portions is made of the same material as a core portion of the waveguide and is included in the same layer (14) as the core portion of the waveguide. [Sixth viewpoint] a plurality of the photoelectric converters are provided, the plurality of photoelectric converters include a first photoelectric converter (161) and a second photoelectric converter (162); The optical waveguide structure according to any one of the first to fifth aspects, wherein the first photoelectric converter is arranged in an orientation different from an orientation in which the second photoelectric converter is arranged, with respect to a center (33a) of a light emitting portion group (33) composed of the plurality of light emitting portions, when viewed in a direction along a third direction (D3) perpendicular to the first direction and the second direction. [Seventh viewpoint] a receiving waveguide (36) for guiding the radiation beam to the photoelectric converter; The optical waveguide structure according to any one of the first to fifth aspects, wherein, when viewed in a direction along a third direction (D3) perpendicular to the first direction and the second direction, the light receiving waveguide extends from the photoelectric converter toward a center (33a) of a light emitting portion group (33) composed of the plurality of light emitting portions. [Eighth viewpoint] The optical waveguide structure according to a seventh aspect, wherein, when viewed in the third direction, the width of the light-receiving waveguide increases as the light-receiving waveguide extends away from the photoelectric converter. [Ninth viewpoint] Each of the plurality of optical antenna sections has a plurality of light output sections (30) arranged along the corresponding waveguide for each of the waveguides, and for emitting light from the waveguide; The optical waveguide structure according to any one of the first to eighth aspects, wherein each of the plurality of light radiating portions is arranged midway along a line (30c) of light exit portions formed by the plurality of light exit portions for each of the waveguides. [10th viewpoint] The optical waveguide structure according to any one of the first to eighth aspects, wherein each of the plurality of light radiating portions is provided on the opposite side of the optical antenna portion to the phase adjuster side for each of the waveguides. [Explanation of symbols]

[0144] 10 Optical waveguide structure 12 PCB 16 Photoelectric converter 22 Waveguide 24 Phase adjuster 26 Optical antenna part Ba radiation beam D1 1st direction D2 2nd direction Pd waveguide pitch

Claims

1. An optical waveguide structure, A substrate (12); a plurality of waveguides (22) provided on the substrate, extending in a first direction (D1), and arranged so as to be aligned at a uniform pitch (Pd) in a second direction (D2) perpendicular to the first direction, for propagating light; a plurality of phase adjusters (24) provided on the substrate for each of the plurality of waveguides, each of which adjusts the phase of light propagating through the waveguide; a plurality of optical antenna units (26) provided on the substrate in the plurality of waveguides, respectively, for radiating light that passes through the phase adjuster and propagates to the waveguides from the waveguides in an antenna unit radiation direction (Dan); a plurality of light radiating sections (34) provided on the substrate in the plurality of waveguides, each of which radiates a portion of light that passes through the phase adjuster and propagates to the waveguide as radiated light from the waveguide in a direction different from the radiation direction of the antenna section; a photoelectric converter (16, 161, 162) provided on the substrate, arranged on one side or the other side or both sides of the plurality of light emitting portions in the second direction, and outputting an electrical signal according to the intensity of incident light; an optical waveguide structure in which the position of the photoelectric converter is determined so that when the phases of the radiation light emitted from each of the plurality of light emitting portions are aligned with each other, radiation beams (Ba, B1a, B2a) formed by the radiation light are incident on the photoelectric converter.

2. Each of the plurality of waveguides has a core width varying portion (341) in which the core width (Wc) of the core portion (221) of the waveguide in the second direction varies locally, The optical waveguide structure according to claim 1 , wherein each of the plurality of light radiating portions is formed by the core width changing portion.

3. Each of the plurality of waveguides has a core width varying portion (341) in which the core width (Wc) of the core portion (221) of the waveguide in the second direction is locally narrowed, The optical waveguide structure according to claim 1 , wherein each of the plurality of light radiating portions is formed by the core width changing portion.

4. 2. The optical waveguide structure according to claim 1, wherein the plurality of light radiating portions are each composed of a radiating component (342) included in a core portion (221) of the waveguide, and a closely-located portion (343) that is provided in the vicinity of the radiating component so as to emit light from the radiating component and is positioned offset in the second direction relative to the radiating component.

5. the closely arranged portions and the plurality of waveguides included in the plurality of light radiating portions are formed to be stacked on the substrate, 5. The optical waveguide structure according to claim 4, wherein each of the closely spaced portions is made of the same material as the core portion of the waveguide and is included in the same layer (14) as the core portion of the waveguide.

6. a plurality of the photoelectric converters are provided, The plurality of photoelectric converters include a first photoelectric converter (161) and a second photoelectric converter (162); 6. The optical waveguide structure according to claim 1, wherein the first photoelectric converter is arranged in an orientation different from an orientation in which the second photoelectric converter is arranged, with respect to a center (33 a) of a light emitting portion group (33) composed of the plurality of light emitting portions, when viewed in a direction along a third direction (D3) perpendicular to the first direction and the second direction.

7. a receiving waveguide (36) for guiding the radiation beam to the photoelectric converter; 6. The optical waveguide structure according to claim 1, wherein, when viewed in a third direction (D3) perpendicular to the first direction and the second direction, the light-receiving waveguide extends from the photoelectric converter toward a center (33 a) of a light emitting portion group (33) composed of the plurality of light emitting portions.

8. 8. The optical waveguide structure according to claim 7, wherein, when viewed in the third direction, the width of the light-receiving waveguide increases as the light-receiving waveguide extends away from the photoelectric converter.

9. Each of the plurality of optical antenna sections has a plurality of light output sections (30) arranged along the waveguide for each of the waveguides and radiating light from the waveguide, 6. The optical waveguide structure according to claim 1, wherein each of the plurality of light radiating portions is disposed midway along a line of light exit portions formed by the plurality of light exit portions for each of the waveguides.

10. 6. The optical waveguide structure according to claim 1, wherein each of the plurality of light radiating portions is provided on the opposite side of the optical antenna portion to the phase adjuster side for each of the waveguides.

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