Optical deflection element and method for manufacturing the same

Abstract

To provide an optical deflection element which is of a hybrid waveguide structure type including different cores, and makes it possible to narrow a pitch of a light emission unit that is needed for expanding a deflection angle.SOLUTION: An optical deflection element 1 includes, on a substrate 31, a plurality of optical waveguides 10 having an optical modulation unit 4 that modulates incident light and a light emission unit 5 that emits modulated light. A core of each of the optical waveguides 10 includes: a first core 11 which is positioned in the light emission unit 5; and a second core 12 which is composed of a refractive index change material having a refractive index smaller than that of the first core 11 and is positioned in the optical modulation unit 4. The first core 11 and the second core 12 are non-contiguous at least between the optical modulation unit 4 and the light emission unit 5. The optical deflection element 1 has core connections 8, 9 where the first core 11 and the second core 12 overlap in a plan view in a longitudinal direction of the cores, and in the core connections 8, 9, the first core 11 and the second core 12, with their positions misaligned in a thickness direction of the substrate 31, are arranged in contact or in proximity.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present invention relates to an optical deflection element and a method for manufacturing the same, and particularly to an optical deflection element of a hybrid waveguide structure type and a method for manufacturing the same.

Background Art

[0002] Optical deflection elements that control the deflection of light have a wide variety of applications in various fields such as 3D video displays, three-dimensional ranging such as LiDAR (Light Detection And Ranging), and biomedical imaging. Conventionally, optical deflection control using polygon mirrors or galvanometer mirrors, and deflection elements using micromachine technology called MEMS (Micro Electro Mechanical Systems) have also been proposed.

[0003] In recent years, research on optical deflection devices using nanophotonics technology without mechanical operating parts has been actively conducted. As an example, array waveguide type optical deflection elements using the thermo-optic (TO: Thermo-Optic) effect or the electro-optic (EO: Electro-Optic) effect can be mentioned. This is an optical deflection element that utilizes the diffraction and interference of light. By controlling the phase of light in each waveguide of the array waveguide by the TO effect, the EO effect, etc., the interference pattern is changed to realize optical deflection.

[0004] An optical waveguide is composed of a core with a high refractive index and a cladding with a lower refractive index than the core, and light is confined and propagated in the core. In an array waveguide type optical deflection element, many are composed of a light incident part, a light splitter, a phase control part (light modulation part) that controls the phase of light, and a light output part.

[0005] In array waveguide-type optical deflection elements utilizing the TO effect, those primarily using silicon (Si) or silicon nitride (chemical formula Si3N4; abbreviated as SiN) as the core are common. These optical deflection elements control the phase of light by changing the refractive index of the core through the TO effect by applying heat to the core via a heater. In addition, for Si, optical deflection elements that utilize the carrier plasma effect, which is the change in refractive index due to a change in the free carrier density in Si, have also been reported.

[0006] In array waveguide-type optical deflection elements utilizing the electro-optical (EO) effect, crystalline materials such as lithium niobate (chemical formula LiNbO3; abbreviation LN) or EO polymers are used for the core (Non-Patent Literature 1). These optical deflection elements exert the EO effect on the core by applying a voltage to it, and control the phase of light by changing the refractive index of the core through the EO effect. EO polymers, in particular, consume less power than materials such as Si and can operate at high speeds of around 100 GHz.

[0007] The deflection angle θ in an array waveguide type optical deflection element depends on the waveguide pitch p in the light emission section, based on the principle of diffraction and interference of light, and is expressed by the following equation (1).

[0008]

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[0009] Here, λ is the wavelength of light, and Δφ is the phase difference between adjacent waveguides. From equation (1), the narrower the waveguide core pitch, the greater the range of the deflection angle θ. To narrow the pitch, it is necessary to make the waveguide core smaller and confine the light to the core so that it does not leak into the cladding. It is known that the greater the difference in refractive index between the waveguide core and the cladding, the stronger the confinement of light to the core. From this, a material with a high refractive index is required for the core, and a material with a low refractive index is required for the cladding.

[0010] Materials used for waveguide cores include silicon (Si), silicon nitride (SiN), lithium niobate (LN), and polymer waveguides based on polyimide, PMMA (polymethyl methacrylate), amorphous perfluororesin (cytop), and epoxy resin. Waveguide cladding often uses silicon dioxide (SiO2) or polymers with a refractive index of approximately 1.5.

[0011] Non-patent document 2 describes a prior example of a hybrid waveguide. This concerns a hybrid structure of a polymer waveguide and an inorganic (SiN) waveguide. Non-patent document 2 states that, in addition to patterning the SiN core and the polymer core, it is necessary to add a step of etching the lower cladding at the optical modulator location in order to align the center of the SiN core with the center of the polymer core. [Prior art documents] [Non-patent literature]

[0012] [Non-Patent Document 1] Yoshikuni Hirano, et al., "Operational Analysis of Optical Phased Arrays Using Electro-Optical Polymers," NHK Science & Technology Research Laboratories R&D, November 2017, No. 166, pp. 46-52. [Non-Patent Document 2] Chul-Soon Im, et al., “Hybrid Integrated Silicon Nitride-Polymer Optical Phased Array For Efficient Light Detection and Ranging,” Journal of Lightwave Technology, Vol. 39, Issue 13, pp. 4402-4409, July1, 2021, doi: 10.1109 / JLT.2021.3070386. [Overview of the project] [Problems that the invention aims to solve]

[0013] When attempting to narrow the pitch of the waveguide core in the light emission section in order to increase the deflection angle θ, the following problems arise. For example, in an array-type optical modulator using EO polymer, the refractive index of EO polymer is about 1.6 to 1.7, making it difficult to narrow the pitch of the array waveguide compared to when using high refractive index materials such as Si or SiN.

[0014] Furthermore, for example, in order for an EO polymer to exhibit the EO effect, the EO polymer layer needs to undergo a poling treatment. Poling is a process that involves heating a material to its glass transition temperature and applying a strong electric field to orient polar molecules. In the case of EO polymers, the poling treatment is a process that orients the EO dyes in the EO polymer to induce second-order nonlinear optical properties.

[0015] While it is desirable to perform poling over the entire polymer layer, in a hybrid waveguide structure that joins an inorganic core and an organic core, if poling is performed with insulators or structures present, the electrodes must not overlap these insulators or structures, thus imposing constraints on the electrode pattern. Due to these constraints on the electrode pattern, it is not possible to perform poling over the entire layer, resulting in uneven orientation of polar molecules such as EO dyes.

[0016] This invention has been made in view of the above-mentioned problems, and aims to provide an optical deflection element that has a hybrid waveguide structure including different cores and enables narrowing of the pitch of the light emission portion necessary for expanding the deflection angle. Furthermore, an objective is to provide a method for manufacturing an optical deflection element that utilizes EO polymers while eliminating factors causing uneven orientation of polar molecules. [Means for solving the problem]

[0017] To solve the above problems, the optical deflection element according to the present invention is an optical deflection element comprising a plurality of optical waveguides on a substrate, each having an optical modulation section for modulating incident light and an optical emission section for emitting modulated light, wherein each core of the optical waveguide comprises a first core disposed in the optical emission section and a second core disposed in the optical modulation section, which is made of a refractive index changing material having a refractive index smaller than that of the first core, the first core and the second core are discontinuous at least between the optical modulation section and the optical emission section, and the first core and the second core have a core connection section in which they overlap in a plan view in the longitudinal direction of the core, and in the core connection section, the first core and the second core are in the thickness direction of the substrate They are stacked on top of each other. It is characterized by being in contact with or in close proximity to others.

[0018] Furthermore, the present invention relates to a method for manufacturing an optical deflection element, comprising a step of forming a first laminate comprising: a first substrate; a lower cladding on the first substrate; a plurality of first cores made of a material having a first refractive index and formed in parallel in a predetermined pattern in a region on the lower cladding that will become the optical emission section; and an intermediate layer that fills the gaps between the first cores; and a step of performing a polling process on a planar core made of a core material having a second refractive index smaller than the first refractive index, and a second substrate and polling The method includes: a second laminate forming step of forming a second laminate comprising a planar core that has been processed and laminated in a predetermined area on the second substrate; a transfer step of transferring the planar core on the second laminate to the area of ​​the first laminate that will become the optical modulation portion, and peeling off the second substrate; and a second core forming step of forming a plurality of second cores by dividing the planar core transferred to the first laminate according to the pattern of the plurality of first cores, wherein the transfer step is characterized in that the plurality of first cores and the planar core have core connection portions that overlap in a plan view in the longitudinal direction of the core, and are transferred in contact with or in close proximity to each other. [Effects of the Invention]

[0019] The present invention has the following excellent effects. According to the optical deflection element of the present invention, since at least the refractive index of the waveguide core of the light emitting portion is larger than the refractive index of the waveguide core of the optical modulation portion, it is possible to provide an optical deflection element capable of narrowing the pitch at the light emitting portion. Therefore, according to the optical deflection element, it is possible to increase the large deflection angle of the optical deflection. Further, according to the method for manufacturing an optical deflection element according to the present invention, it is possible to perform poling treatment on a planar core in a film state without a waveguide pattern or the like. Therefore, it is possible to eliminate the factors of uneven alignment of polar molecules and use an EO polymer as a material for the planar core, and it is possible to perform poling treatment on the EO polymer more uniformly.

Brief Description of the Drawings

[0020] [Figure 1] It is a schematic diagram of an optical deflection element according to a first embodiment of the present invention, where (a) is a plan view showing the arrangement of cores through the cladding of an optical waveguide, (b) is an enlarged view of the core connection portion on the incident side, and (c) is an enlarged view of the core connection portion on the emission side. [Figure 2] It is a cross-sectional view schematically showing the optical waveguide of the optical deflection element of FIG. 1, where (a) to (d) are cross-sectional views taken along the arrow A-A to D-D of FIG. 1, respectively. [Figure 3] It is a configuration example of an optical distribution unit, where (a) shows a configuration example of a 1×8 MMI coupler, and (b) shows a configuration example of a cascade connection of 1×2 MMI couplers. [Figure 4] It is a schematic diagram of a method for manufacturing an optical deflection element according to an embodiment of the present invention, where (a) to (e) are cross-sectional views showing the manufacturing process, and (f) is a plan view. [Figure 5] It is a schematic diagram of a method for manufacturing an optical deflection element according to an embodiment of the present invention, where (a) to (c) are cross-sectional views showing the manufacturing process, and (d) is a plan view. [Figure 6]This is a schematic diagram of a method for manufacturing an optical deflection element according to an embodiment of the present invention, where (a) is a plan view showing the manufacturing process, and (b) to (d) are cross-sectional views showing the manufacturing process. [Figure 7] This is a schematic plan view showing a method for manufacturing an optical deflection element according to an embodiment of the present invention. [Figure 8] A schematic diagram of an optical deflection element according to a second embodiment of the present invention, where (a) is a plan view showing the arrangement of the cores transmitted through the cladding of the optical waveguide, (b) is an enlarged view of the core connection on the incident side, and (c) is an enlarged view of the core connection on the exit side. [Figure 9] (a) to (c) show modified examples of the phase shifter configuration in the optical modulation section, respectively. [Figure 10] This is an explanatory diagram of Example 1, where (a) is a longitudinal cross-sectional view mainly of the optical modulation section, (b) is a planar perspective view of the core connection section on the output side, and (c) is a graph showing the optical output simulation results. [Figure 11] This is a longitudinal cross-sectional view of the comparative example, mainly in the optical modulation section. [Figure 12] This graph shows the phase control simulation results for Example 1 and the comparative example. [Figure 13] This is an explanatory diagram of Example 2, where (a) is a longitudinal cross-sectional view mainly of the optical modulation section, (b) is a planar perspective view of the core connection section on the output side, and (c) is a graph showing the optical output simulation results. [Modes for carrying out the invention]

[0021] [Overall configuration of the optical deflection element] The overall configuration of the optical deflection element of this embodiment will be described with reference to Figure 1 (and Figure 2 as appropriate). Note that the sizes and positional relationships of the components shown in each drawing may be exaggerated for clarity of explanation.

[0022] The optical deflection element 1 comprises a plurality (e.g., 8) optical waveguides 10 on a substrate 31, each having an optical modulation section 4 for modulating incident light and an optical emission section 5 for emitting the modulated light. Each core of the optical waveguide 10 comprises a first core 11 located in the optical emission section 5 and a second core 12 located in the optical modulation section 4, made of a refractive index changing material having a refractive index smaller than that of the first core 11. The optical deflection element 1 is provided with cladding 32 around the optical waveguide cores 11 and 12. The first core 11 and the second core 12 are discontinuous at least between the optical modulation section 4 and the optical emission section 5 (core connection peripheral section 22). Figure 1(c) is an enlarged view of the core connection peripheral section 22. As shown in Figure 1(c), the optical deflection element 1 has a core connection section 9 where the first core 11 and the second core 12 overlap in a plan view in the longitudinal direction of the core. In the core connection section 9, the first core 11 and the second core 12 are positioned in contact with or in close proximity to each other, with their positions offset in the thickness direction of the substrate 31.

[0023] As shown in Figure 1(a), the optical deflection element 1 comprises an optical incident section 2, an optical distribution section 3, an optical modulation section 4, and an optical emission section 5. Here, the optical waveguide 10, which is located on the incident side of the optical modulation section 4, the optical incident section 2, and the optical distribution section 3 are collectively referred to as the introduction section 6. The introduction section 6 introduces incident light into the optical modulation section 4. In this embodiment, each core of the optical waveguide 10 is discontinuous between the introduction section 6 and the optical modulation section 4 (core connection peripheral section 21), and also discontinuous between the optical modulation section 4 and the optical emission section 5 (core connection peripheral section 22), with the first core 11 positioned between the optical emission section 5 and the introduction section 6. Figure 1(b) is an enlarged view of the core connection peripheral section 21. As shown in Figure 1(b), the optical deflection element 1 has a core connection section 8 where the first core 11 and the second core 12 overlap in a plan view in the longitudinal direction of the cores. In the core connection section 8, the first core 11 and the second core 12 are positioned in contact or in close proximity to each other, with their positions offset in the thickness direction of the substrate 31.

[0024] [Configuration of each part of the optical deflection element] The configuration of each part of the optical deflection element of this embodiment will be explained with reference to Figure 2 (and to Figure 1 as appropriate). Figure 2(a) shows the cross-sectional view along line AA in Figure 1(b) and the cross-sectional view along line AA in Figure 1(c). Figure 2(b) shows the cross-sectional view along line BB in Figure 1(b) and the cross-sectional view along line BB in Figure 1(c). Figure 2(c) shows the cross-sectional view along line CC in Figure 1(b) and the cross-sectional view along line CC in Figure 1(c). Figure 2(d) shows the cross-sectional view along line DD in Figure 1(b) and the cross-sectional view along line DD in Figure 1(c).

[0025] The light incidence section 2 is an element for inputting light to the element from the outside. The input method may be to input light from a waveguide on the end face of the element, or it may be incident from the direction perpendicular to the surface by using a grating coupler structure. Figure 1(a) assumes one input of light, but multiple (N inputs) may also be used. In this embodiment, one input is assumed. A laser is preferable as the light source for inputting light to the light incidence section 2 because it has excellent coherence and can adjust polarization, but an LED (light-emitting diode) or SLD (superluminescent diode) may also be used.

[0026] The cross-section of the optical waveguide of the light incident section 2 is the same as the cross-section shown in Figure 2(a). As shown in Figure 2(a), the light incident section 2 comprises a cladding 32 and a first core 11 on a substrate 31. The cladding 32 comprises a lower cladding 32a, an intermediate layer 32b, and an upper cladding 32c, which are laminated in, for example, three different processes during the manufacturing of the optical deflection element 1. The lower cladding 32a is located below the first core 11 (on the substrate 31 side). The upper cladding 32c is located above the first core 11. The intermediate layer 32b is located between the lower cladding 32a and the upper cladding 32c. When not specifically distinguished, they are simply referred to as cladding 32.

[0027] The optical distribution unit 3 is an element that distributes the light input from the optical incident unit 2 to the optical waveguides 10 that constitute the optical modulation unit 4, with equal intensity. In this embodiment, optical distribution to eight waveguides is performed using a 1-input, 8-branch multimode interference (1x8MMI). As for the distribution method, in addition to using 1x8MMI, 1xnMMI (n: an integer of 2 or more, e.g., 1x2) or Y-branching may be used and arranged in a cascaded manner. The optical distribution unit 3 shown in Figure 3(a) is an example composed of a 1x8MMI coupler, and the optical distribution unit 3A shown in Figure 3(b) is an example composed of a cascaded connection of 1x2MMI couplers. Note that the cross-section of one of the output optical waveguides of the optical distribution unit 3 is the same as the cross-section shown in Figure 2(a).

[0028] The optical modulation unit 4 is an element that controls the phase of light and is equipped with a phase shifter. In this embodiment, the effective refractive index of light propagating through the core is changed by the EO effect caused by voltage application, thereby enabling phase modulation (optical modulation) of light for each optical waveguide 10. The cross-section of the optical modulation section 4, across one optical waveguide, is the same as the cross-section shown in Figure 2(d). As shown in Figure 2(d), the optical modulation unit 4 includes a first electrode 41 and a second electrode 42 as phase shifters. The optical modulation unit 4 uses a second core 12 as a waveguide core, and the second core 12 is sandwiched between two electrodes, the first electrode 41 and the second electrode 42, which are positioned perpendicular to the core. Note that the second core 12 does not need to be in contact with the first electrode 41 or the second electrode 42.

[0029] The first electrode 41 is not patterned along the optical waveguide 10. Of course, it may be patterned according to the optical waveguide 10. The second electrode 42 is patterned along the optical waveguide 10. In order to control each optical waveguide 10 individually, it is sufficient for either the first electrode 41 or the second electrode 42 to be patterned according to the optical waveguide 10.

[0030] In this embodiment, the first electrode 41 is a common electrode for, for example, multiple (e.g., eight) second cores 12 and is grounded. The first electrode 41 is located, for example, on the underside of the second cores 12. The second electrode 42 is an electrode provided for applying individual voltages V1 to V8 (see Figure 1(a)) to, for example, multiple (e.g., eight) second cores 12. The second electrode 42 is located independently of each second core 12 and does not cross or come into contact with one another. The second electrode 42 is located, for example, on the upper side of the second cores 12.

[0031] For the first electrode 41 and the second electrode 42, metal electrodes made of Ti, Cr, Au, Cu, or Al, or transparent electrodes made of ZnO, ITO (Indium Tin Oxide), or IZO (Indium Zinc Oxide) can be selected. Since the first electrode 41 or the second electrode 42 needs to be patterned, patternable materials are desirable.

[0032] A voltage is applied to the second electrode 42 via the signal line 43. Each waveguide 10 is connected to a voltage source that applies individual voltages V1 to V8 via the signal line 43. The terminal of the other polarity of the voltage source is connected to the first electrode 41. The material of the signal line 43 is the same as the material used for the first electrode 41 and the second electrode 42.

[0033] The light emission section 5 is an element that outputs light to the outside of the element. In this embodiment, the light emission section 5 is configured as an output from the end face of the element, but it may also be configured as an output in the direction perpendicular to the surface by applying a grating coupler structure. The pitch between the optical waveguides 10 (second core 12) in the optical modulation section 4 is different from the pitch between the optical waveguides 10 (first core 11) at the output end face of the optical output section 5. A curved waveguide was provided in the optical waveguide 10 (first core 11) located between the optical modulation section 4 and the output end face of the optical output section 5 to adjust the pitch. The optical output section 5 is an element that starts from the right end of the optical modulation section 4 in Figure 1(a) (the right end of the second electrode 42) and extends through the curved waveguide to the end of the element (to the far right end). The cross-section of one optical waveguide in the optical output section 5 is the same as the cross-section shown in Figure 2(a).

[0034] The optical waveguide 10 comprises a core (first core 11 or second core 12) and a cladding 32. It is desirable to use a core with a refractive index higher than that of the cladding. Hereinafter, the refractive index of the material of the first core 11 will be referred to as the first refractive index, and the refractive index of the material of the second core 12 will be referred to as the second refractive index. The second refractive index is smaller than the first refractive index. When the optical deflection element 1 is a hybrid waveguide structure type using organic and inorganic materials, it is preferable that the first core 11 is made of inorganic material and the second core 12 is made of organic material.

[0035] As one example, it is preferable that the first core 11 is made of SiN (refractive index 1.965), and the second core 12 is made of an EO polymer that exhibits an EO effect as a refractive index changing material. By using SiN, the usable wavelength range can be applied from visible light to infrared. Furthermore, if the operating wavelength range is limited to the communication band of 1.3 to 1.6 μm, the first core 11 may be formed of Si (refractive index 3.5). Furthermore, the first core 11 may be formed from lithium niobate (LiNbO3) or niobium pentoxide (Nb2O5), which are materials having wavelength and refractive index characteristics equivalent to SiN.

[0036] The second core 12 is preferably formed of an EO polymer that exhibits an electro-optic effect (EO effect) as a refractive index changing material. As an EO polymer, for example, a polymer material can be used in which an organic dye exhibiting a nonlinear response is dispersed in a polymethyl methacrylate (PMMA) base. In addition, disperse red and other dyes can be applied as EO dyes. For example, when utilizing the electro-optic effect, the second core 12 may be formed of LiNbO3, LiTaO2, or Al2O3. When the second core 12 is formed of a refractive index changing material that exhibits an EO effect, the refractive index changes due to the electric field applied between the first electrode 41 and the second electrode 42, and contributes to optical modulation by changing the phase of light.

[0037] As shown in Figure 2(d), the optical modulation section 4 has a second core 12 that contributes to optical modulation, for example by exhibiting an EO effect, but there is no first core 11 facing or opposite it in the longitudinal direction. If the first core 11 is a SiN core, the refractive index does not change in an electric field and therefore does not contribute to optical modulation. In the conventional technology, in an optical modulation section, in a structure where two cores, one that does not cause a change in refractive index and one that does, coexist in close proximity, light propagates by moving alternately through each core, thus reducing the optical modulation efficiency. However, in the optical deflection element 1 according to this embodiment, since there is no first core 11 that does not contribute to optical modulation in the optical modulation section 4, the optical deflection element 1 propagates light in the optical modulation section 4 by the second core 12, thus suppressing a decrease in optical modulation efficiency.

[0038] Core connection sections 8 and 9 are parts that exchange light propagation between different core layers, different core materials, and different core shapes. Core connection section 8 is an element for coupling and propagating light propagating through the first core 11 to the second core 12, and core connection section 9 is an element for coupling and propagating light propagating through the second core 12 to the first core 11.

[0039] As shown in Figures 1(b) and 1(c), the first core 11 has an end face 11e at the core connection portions 8 and 9, and is positioned so as to overlap with the second core 12 in the longitudinal direction in a plan view, and as shown in Figure 2(b), is offset from the second core 12 in the thickness direction. Furthermore, at the core connection portions 8 and 9, the first core 11 and the second core 12 are in contact with or in close proximity in the thickness direction. Preferably, at the core connection portions 8 and 9, the first core 11 is formed in a tapered shape so that the core width in a plan view tapers towards the end face 11e. Note that the core width at the end of the first core 11 in a plan view does not have to be tapered; it may be the same thickness.

[0040] However, high bonding efficiency can be obtained by applying a tapered structure to the first core 11. The ratio of the width at the tapered end face 11e to the overall core width of the first core 11 excluding the tip is determined in conjunction with the effective refractive index in the second core 12. The ratio of the width at the end face 11e to the core width of the first core 11 may be, for example, around 0.5.

[0041] At core connection points 8 and 9, the second core 12 exists from the taper start point of the first core 11. The direction of the taper at core connection point 9 is rotated 180 degrees relative to the direction of the taper at core connection point 8. The length from the taper start point of the first core 11 to the end face 11e (taper length) is determined by the beat caused by the interference between light that can propagate between the first core 11 and the second core 12. In the thickness direction of the substrate 31, the first core 11 and the second core 12 are in close contact, or there may be a gap between the two cores due to the cladding material. If a gap is provided due to the cladding material, the gap width is determined in consideration of the effective refractive index in the second core 12.

[0042] As shown in Figure 2(a), the cladding 32 comprises, for example, a lower cladding 32a, an intermediate layer 32b, and an upper cladding 32c. The lower cladding 32a is provided between the substrate 31 and the first core 11. The material for the lower cladding 32a should have a refractive index lower than that of the core of the optical waveguide 10, and the refractive index difference between the two should be as large as possible. For example, SiO2 (refractive index 1.48) can be used. Alternatively, a polymer resin (acrylate-based, epoxy-based) with a refractive index of around 1.5 may be used.

[0043] In Figure 2(a), the first core 11 is formed on the dashed line indicating the boundary between the lower cladding 32a and the intermediate layer 32b. In Figure 2(a), the dashed line indicating the boundary between the intermediate layer 32b and the upper cladding 32c represents the bonded surface where the two substrates were bonded together during manufacturing. The intermediate layer 32b is provided on the lower cladding 32a around the first core 11, covering the sides of the first core 11. The intermediate layer 32b is formed before the two substrates are bonded together during manufacturing. The material of the intermediate layer 32b may be the same as or different from the material of the lower cladding 32a. The upper surface of the intermediate layer 32b may be flush with the upper surface of the first core 11, or the upper surface of the intermediate layer 32b may be higher than the upper surface of the first core 11.

[0044] The upper cladding 32c is provided on the intermediate layer 32b so as to cover the upper surface of the second core 12. The upper cladding 32c is applied to the second core 12 after the two substrates are bonded together during manufacturing, one substrate is peeled off, and the second core 12 is formed on the other substrate side. The material of the upper cladding 32c may be the same as or different from the material of the lower cladding 32a. The upper cladding 32c may also be an air layer. As shown in Figure 2(d), cladding material may be present between the first core 11 and the first electrode 41, between the second core 12 and the first electrode 41, and between the second core 12 and the second electrode 42.

[0045] The substrate 31 can be made of a material with sufficient mechanical strength to support each layer, but it is preferable to select one with a small difference in the coefficient of thermal expansion between each layer. For example, a Si substrate or a glass substrate is preferable.

[0046] According to the optical deflection element of this embodiment, since the refractive index of the first core 11, which is at least located in the light emission section 5, is greater than the refractive index of the second core 12, which is located in the light modulation section 4, it is possible to provide an optical deflection element that allows for a narrower pitch at the emission end of the light emission section 5. Therefore, the optical deflection element 1 enables a large deflection angle for optical deflection.

[0047] [Manufacturing method for optical deflection elements] Next, the method for manufacturing the optical deflection element of this embodiment will be described with reference to Figures 4 to 7. The method for manufacturing the optical deflection element includes a first laminate formation step, a second laminate formation step, a transfer step, and a second core formation step. The first laminate formation process will be explained with reference to Figure 4 (and Figure 1 as appropriate). Figures 4(a) to 4(e) are schematic cross-sectional views showing each lamination process in which each component is laminated, and represent cross-sectional views corresponding to the cross-section along the dashed line L1 in Figure 1(a). First, as shown in Figure 4(a), a substrate (first substrate) 31 is prepared. Next, as shown in Figure 4(b), a first electrode 41 made of a conductive material is formed on the substrate 31 in accordance with the pattern of the first core 11.

[0048] Next, as shown in Figure 4(c), a lower cladding 32a is formed on the first electrode 41 and on the substrate 31. If the material of the lower cladding 32a is, for example, SiO2, a film deposition method such as CVD (chemical vapor deposition) can be used. If the material of the lower cladding 32a is, for example, a polymer resin, a film deposition method using spin coating and UV irradiation can be employed. The thickness of the lower cladding 32a is such that light propagating through the core does not reach the substrate 31. Preferably, the lower cladding 32a has a thickness of, for example, 2 μm or more. However, the required thickness will vary depending on the wavelength of light used in the optical deflection element 1, the refractive index of the core, and the size of the core, so it should be set appropriately according to these conditions.

[0049] Next, as shown in Figure 4(d), multiple first cores 11 are formed in parallel in a predetermined pattern on the lower cladding 32a in the regions that will become the introduction section 6 (light incident section 2, light distribution section 3, etc.) and the light emission section 5, using a material having a first refractive index. Assuming that the operating wavelength range is from visible light to infrared, if SiN is used as the first core 11, the SiN film can be fabricated by CVD or other methods.

[0050] Next, as shown in Figure 4(e), the first laminate 50 is formed by forming an intermediate layer 32b that fills the gaps between the first cores 11 using a predetermined cladding material. The first laminate 50 comprises a substrate 31, a lower cladding 32a on the substrate 31, a plurality of first cores 11 made of a material having a first refractive index and formed in parallel in a predetermined pattern in at least the region that will become the light-emitting portion 5 on the lower cladding 32a, and an intermediate layer 32b that fills the gaps between the first cores 11. Figure 4(f) is a plan view of the first laminate 50.

[0051] Next, the second laminate formation process and the transfer process will be explained with reference to Figure 5 (and Figure 1 as appropriate). Figures 5(b) to 5(c) schematically show cross-sectional views corresponding to the cross-section along the dashed line L1 in Figure 4(f). First, as shown in Figure 5(a), a second substrate 61 is prepared, and a planar core 62 is formed in a predetermined area on the second substrate 61 using a core material having a second refractive index. A polling process is then performed on this planar core 62 to form a second laminate 63 comprising the second substrate 61 and the polled planar core 62. The refractive index of the planar core 62 (second refractive index) is smaller than the refractive index of the first core 11 (first refractive index). When using, for example, an EO polymer material as the core material for the planar core 62, the EO polymer core is fabricated as the planar core 62 by spin coating. The size of the core should preferably be such that single-mode propagation is permitted.

[0052] Next, as shown in Figure 5(b), the planar core 62 on the second laminate 63 is bonded to the region of the first laminate 50 that will become the optical modulation section 4, and the planar core 62 is transferred to the first laminate 50 by peeling off the second substrate 61 as shown in Figure 5(c). The transfer process is carried out so that the multiple first cores 11 and the planar core 62 have core connection sections that overlap in a plan view in the longitudinal direction of the cores, and are in contact with or in close proximity to each other. The core connection peripheral sections 64 and 65 in Figure 5(c) include the locations that will become the core connection sections 8 and 9 (see Figure 1). Figure 5(d) is a plan view of the planar core 62 transferred to the first laminate 50.

[0053] Furthermore, the method for peeling off the second substrate 61 after bonding the first laminate 50 and the second laminate 63 can be achieved by utilizing the fact that the adhesion between the first laminate 50 and the planar core 62 is higher than the adhesion between the second substrate 61 and the planar core 62. Conventional known methods can be used to improve such adhesion.

[0054] Next, in the second core formation step, the planar core 62 transferred to the first laminate 50 is divided into multiple second cores 12 by etching according to the patterns of the multiple first cores 11, as shown in Figure 6(a). Figure 6(b) schematically shows a cross-sectional view along the dashed line L1 in Figure 6(a).

[0055] Next, the process may further include an upper cladding step, for example, as shown in Figure 6(c), to form an upper cladding 32c that covers the intermediate layer 32b and the plurality of second cores 12. Furthermore, for example, as shown in Figure 6(d), a plurality of second electrodes 42 made of a conductive material and aligned with the pattern of the second cores 12 may be formed on the upper cladding 32c. Figure 7 is a plan view of the plurality of second electrodes 42.

[0056] Conventional manufacturing methods for hybrid waveguide structures that join inorganic and organic cores require poling with insulators and structures present, making it impossible to perform poling across the entire surface and resulting in uneven orientation of polar molecules such as EO dyes. Furthermore, in conventional manufacturing methods, when poling is performed with insulators and structures present, the lower cladding needs to be made of a material that has a low refractive index, is transparent to the wavelength of use, and has high conductivity. Conventional techniques use materials such as sol-gel organic silica, but although sol-gel organic silica has higher conductivity than SiO2, it has challenges in achieving stable film deposition quality. In contrast, according to the manufacturing method of the optical deflection element of this embodiment, polling can be performed on a planar core 62 in a film state without waveguide patterns, thus eliminating the factor of uneven orientation of polar molecules and enabling the use of EO polymer. Therefore, there is no need to use a sol-gel organic silica film in the first place, and a stable film-forming material such as SiO2 can be used.

[0057] Furthermore, according to the manufacturing method of the optical deflection element according to this embodiment, a pre-polled EO polymer can be used as the core (second core 12) in the optical modulation section 4. Therefore, an inorganic waveguide such as a SiN core (first core 11) that does not contribute to optical modulation is not required between the first electrode 41 and the second electrode 42 in the optical modulation section 4. As a result, the optical deflection element 1 can have only the second core 12 in the optical modulation section 4 without arranging the first core 11 that does not contribute to optical modulation. Consequently, it is possible to suppress the decrease in optical modulation efficiency caused by a structure in which two different cores coexist in close proximity in the optical modulation section.

[0058] (Second Embodiment) Next, an optical deflection element according to the second embodiment of the present invention will be described with reference to Figure 8 (and to Figures 1 and 2 as appropriate). In Figure 8(a), the same reference numerals are used for components that are the same as those in Figure 1(a), and their descriptions are omitted as appropriate. Also, Figure 2(a) schematically shows the cross-sectional view along line AA in Figure 8(b) and the cross-sectional view along line AA in Figure 8(c). Figure 2(b) schematically shows the cross-sectional view along line BB in Figure 8(b) and the cross-sectional view along line BB in Figure 8(c). Figure 2(c) schematically shows the cross-sectional view along line CC in Figure 8(b) and the cross-sectional view along line CC in Figure 8(c). Figure 2(d) schematically shows the cross-sectional view along line DD in Figure 8(b) and the cross-sectional view along line DD in Figure 8(c).

[0059] As shown in Figure 8(a), the optical deflection element 1B has a plurality (for example, 8) optical waveguides 10 on a substrate 31, each having an optical modulation section 4B for modulating incident light and an optical emission section 5 for emitting the modulated light. Each core of the optical waveguide 10 of the optical deflection element 1B includes a first core 11 located in the optical emission section 5 and the introduction section 6, and a second core 12 located in the optical modulation section 4B. Furthermore, each core of the optical waveguide 10 is discontinuous between the introduction section 6 and the optical modulation section 4 (core connection peripheral section 21B), and also discontinuous between the optical modulation section 4 and the optical emission section 5 (core connection peripheral section 22B). Figure 8(b) is an enlarged view of the core connection peripheral section 21B, and Figure 8(c) is an enlarged view of the core connection peripheral section 22B.

[0060] As shown in Figures 8(b) and 8(c), the first core 11 is positioned so as to overlap with the second core 12 in the longitudinal direction in a plan view, and as shown in Figure 2(b), it is offset from the second core 12 in the thickness direction. Furthermore, at the core connection portions 8 and 9, the first core 11 and the second core 12 are in contact with or in close proximity to each other in the thickness direction.

[0061] As shown in Figures 8(b) and 8(c), the optical deflection element 1B has a first core 11 with end faces 11e at the core connection portions 8 and 9, and the width of the first core 11 in plan view is minimum and constant at the core connection portions 8 and 9. In addition, in the adjacent regions 78 and 79 adjacent to the core connection portions 8 and 9, the first core 11 is formed in a tapered shape, with the core width in plan view narrowing towards the core connection portions 8 and 9.

[0062] Here, the adjacent region 78 is adjacent to the core connection portion 8 in the core connection peripheral portion 21B. The shape of the core connection portion 8 in plan view is rectangular, not tapered. That is, the area where the second core 12 covers the first core 11 (core connection portion 8) is a straight waveguide only. Also, the adjacent region 79 is adjacent to the core connection portion 9 in the core connection peripheral portion 22B. The shape of the core connection portion 9 in plan view is rectangular, not tapered. That is, the area where the second core 12 covers the first core 11 (core connection portion 9) is a straight waveguide only.

[0063] As shown in Figures 1(b) and 1(c), when the second core 12 covers the upper part of the tapered structure of the first core 11, the resulting beats are non-periodic, requiring numerical analysis to calculate the appropriate taper length at the covered portion. On the other hand, in the structures shown in Figures 8(b) and 8(c), the portions where the second core 12 covers the first core 11 (core connection portions 8 and 9) are straight waveguides, so the resulting beats are periodic. That is, in the optical deflection element 1B, when designing the optical waveguide, the beat length at the core connection portions 8 and 9 can be easily calculated by considering only two effective refractive indices with respect to the optical propagation direction. The lengths of the core connection portions 8 and 9 (length of the straight waveguide) should be designed to correspond to this beat length.

[0064] The beat length L at wavelength λ is given by equation (2) below, where n1 and n2 are the two effective refractive indices related to the first core 11 and the second core 12. K is the coupling coefficient between the waveguides.

[0065]

number

[0066] According to this embodiment, the lengths of the core connection portions 8 and 9 can be easily determined compared to the case where the second core 12 covers the upper part of the tapered structure of the first core 11. The manufacturing method of the optical deflection element according to the second embodiment is the same as the manufacturing method according to the first embodiment, except that the shape pattern of the end of the first core 11 is changed.

[0067] Although the optical deflection elements according to each embodiment of the present invention have been described above, the spirit of the present invention is not limited to these descriptions and must be interpreted broadly based on the claims. Furthermore, it goes without saying that various modifications and alterations based on these descriptions are also included in the spirit of the present invention. For example, the optical deflection element 1 has a tapered structure on the incident and exit sides as viewed from the optical modulation unit 4 at the connection between the first core 11 and the second core 12, but it may also have a tapered structure only on the exit side. The optical deflection element 1 has a connection between the first core 11 and the second core 12 on the incident and exit sides as viewed from the optical modulation unit 4, but it may also have a connection between the second core 12 and the first core 11 only on the exit side. Even in such a configuration, since the refractive index of the waveguide core of the optical exit unit 5 is greater than the refractive index of the waveguide core of the optical modulation unit 4, it is possible to narrow the pitch in the optical exit unit 5.

[0068] In each of the above embodiments, the first electrode 41 was directly laminated on the substrate 31 in the optical modulation section 4, 4B as shown in Figure 2(d). However, from the viewpoint of insulation, an insulating material such as SiO2 of about 100 to 200 nm may be laminated between the substrate 31 and the first electrode 41.

[0069] In the embodiments described above, the first electrode 41 in the optical modulation section 4, 4B was formed on the substrate 31 spaced apart from the second core 12, but the first electrode 41C shown in Figure 9(a) may also be used. The first electrode 41C is bonded to the lower surface of the second core 12. When manufacturing an optical deflection element of this form, for example, the first electrode 41C can be formed on the second laminate 63 before bonding the first laminate 50 and the second laminate 63 shown in Figure 5(a). In this case, the second laminate 63 shown in Figure 5(a) can be formed, then a cladding layer can be laminated around the planar core 62, and the first electrode 41C can be formed so as to cover the cladding layer and the upper surface of the planar core 62.

[0070] In the embodiments described above, the optical modulation section 4, 4B is configured to sandwich the second core 12 from above and below using two electrodes (first electrode 41, second electrode 42), but the configuration is not limited to sandwiching from above and below. For example, as shown in Figure 9(b), the first electrode 41 may be patterned and placed below each second core 12, and the second electrode 42D may be placed between two adjacent second cores 12 at the same height as the first electrode 41. In this case, the first electrode 41 applies an individual voltage to each second core 12. The second electrode 42D is a common electrode for the two second cores 12 on either side of it and is grounded.

[0071] Similarly, for example, as shown in Figure 9(c), the second electrode 42 may be patterned and positioned above each second core 12, and the first electrode 41E may be positioned between two adjacent second cores 12 at the same height as the second electrode 42. In this case, the second electrode 42 applies a separate voltage to each second core 12. The first electrode 41E is a common electrode for the two second cores 12 on either side of it and is grounded.

[0072] In the embodiments described above, the second core 12 arranged in the optical modulation sections 4 and 4B is assumed to be a refractive index changing material that exhibits the EO effect, but thermo-optic effect (TO effect) or carrier plasma effect material may also be used. When using the TO effect or carrier plasma effect, the second core 12 is formed from one material selected from the group consisting of Si, SiN, and InP. For example, when the TO effect is used as the operating principle, the phase shifter is composed of a heater (resistor) that generates Joule heat by the flowing current, and a current as a control signal is injected. When the second core 12 is formed from a refractive index changing material that exhibits the TO effect, the refractive index changes due to Joule heat, and contributes to optical modulation by changing the phase of light. It is preferable that the first core 11 has a higher refractive index than the second core 12 and is made of a material that does not contribute to optical modulation.

[0073] Furthermore, in the manufacturing method of the optical deflection element, the size of the second substrate 61 shown in Figure 5(a) may differ from the size of the substrate 31 shown in Figure 4(a). However, it is preferable that the substrates be the same size, as this eliminates the need for alignment.

[0074] [simulation] The inventors of this application confirmed the effect of the optical deflection element 1 by performing the following simulations. The optical deflection element 1 is equipped with eight optical waveguides, and assuming that the wavelength range of the light used is from visible light to infrared, the following two experiments (optical output simulation and phase control simulation) were performed.

[0075] (Light output simulation) First, the calculation conditions will be explained with reference to Figure 10 (and other drawings such as Figure 1 as appropriate). Figure 10(a) shows the longitudinal cross-sectional structure corresponding to the optical output simulation calculation range. This calculation range mainly includes the optical modulation section 4. Figure 10(b) shows an enlarged view of the core connection peripheral section 81 shown in Figure 10(a), viewed from above through the cladding.

[0076] In the structure shown in Figure 10(a), the core of the optical waveguide 10 is discontinuous between the introduction section 6 and the optical modulation section 4, and also discontinuous between the optical modulation section 4 and the optical emission section 5. The first core 11 is located in the optical emission section 5 and the introduction section 6, and the second core 12 is located in the optical modulation section 4. The optical modulation section 4 has a first electrode 41 and a second electrode 42. The second core 12 has a portion sandwiched between the first electrode 41 and the second electrode 42, but the first core 11 does not have a portion sandwiched between the first electrode 41 and the second electrode 42. Therefore, the optical modulation section 4 does not have a first core 11. The structure shown in Figures 10(a) and 10(b) is referred to as Example 1. The materials, refractive indices, and scales of each part of Example 1 are as follows. Note that in each drawing, the length, width, and thickness are exaggerated to make the characteristics of the components easier to understand.

[0077] <Second Core 12> Second core material: EO polymer (refractive index 1.66) Width of the second core: 1.5 μm Thickness of the second core: 1.5 μm

[0078] <1st Core 11> Material of the first core: SiN (refractive index 1.965) Width of the first core: 1.0 μm (excluding the core connection area) Thickness of the first core: 0.5 μm

[0079] <Core connection sections 8, 9 (however, size of the first core)> Width of the proximal end of the core connection: 1.0 μm Width of the tip of the core connection: 0.5 μm Core connection length: 130 μm Distance between the top surface of the first core and the bottom surface of the second core at the core connection point: 0.3 μm

[0080] <Cladding 32, lower cladding 32a, intermediate layer 32b, upper cladding 32c> Cladding material (common): SiO2 (refractive index 1.48) Lower cladding thickness (cladding thickness from the top surface of the substrate to the bottom surface of the first core): 3 μm Interlayer thickness: 0.8 μm Upper cladding thickness (cladding thickness from the bottom surface of the second core to the bottom surface of the second electrode): 4.5 μm Cladding thickness from the top surface of the second core to the bottom surface of the second electrode: 3 μm Cladding thickness from the top surface of the first electrode to the bottom surface of the second core: 3.6 μm Cladding thickness from the top surface of the substrate to the bottom surface of the second core: 3.8 μm

[0081] <Substrate 31, first electrode 41, second electrode 42, waveguide pitch, waveguide length> Substrate material: Si substrate Thickness of the first electrode: 0.2 μm Thickness of the second electrode: 0.2 μm Width of the second electrode: 1.5 μm The second core 12 and the second electrode 42 were arranged in parallel in eight configurations with a 20 μm pitch. The waveguide pitch at the output end of the light output section 5 was set to a 2.5 μm pitch. Waveguide length within the optical output simulation calculation range: 2000 μm This waveguide length corresponds to the length in the Z-axis direction in the cross-sectional view of Figure 10(a).

[0082] Figure 10(c) shows the optical output simulation results for Example 1. The simulation was performed using OptiBPM from Optiwave. The horizontal axis of the graph in Figure 10(c) represents the length in the Z-axis direction of the cross-sectional view in Figure 10(a). In Figure 10(a), the left end of the first core 11 on the incident side is at Z=0μm, and the right end of the first core 11 on the exit side is at Z=2000μm. The vertical axis of the graph in Figure 10(c) represents the optical intensity in arbitrary units (au). This optical intensity is a one-dimensional distribution of optical intensity along the dashed line (Z-axis) in Figure 10(a). Therefore, the optical intensity in the range where no cores exist on the dashed line (Z-axis) (Z=approximately 300~1300nm) is 0. As shown in the figure, when the input optical intensity is 1, the output obtained at the output end is 0.8, and the output ratio to input (output / input) is 80%. In the optical modulation section, a structure in which two cores—one that does not cause a change in refractive index and another that does—coexist in close proximity reduces the optical modulation efficiency. However, the structure of Example 1 was able to significantly suppress the decrease in optical modulation efficiency. Example 1 showed that by applying a tapered structure to the core connection sections 8 and 9, a high-efficiency output with a coupling efficiency of 80% could be obtained.

[0083] (Phase control simulation) In the phase control simulation, the phase control in the structure of Example 1 was calculated. As a comparative example, the phase control in the structure shown in Figure 11 was also calculated. The optical deflection element 101 of the comparative example shown in Figure 11 comprises a first core 11 and a second core 12 as the core of the optical waveguide, and the materials, refractive index, and scale of each part of the comparative example are the same as those of Example 1. However, the comparative example has a structure in which the first core 11 is arranged continuously from the incident side to the exit side. Therefore, in the comparative example, the first core 11 is located in the portion sandwiched between the first electrode 41 and the second electrode 42, meaning that the optical modulation section has a SiN core (first core 11) that does not contribute to optical modulation. Furthermore, the comparative example does not have a tapered structure in the first core 11.

[0084] Figure 12 shows the phase control simulation results for the structure of Example 1. The horizontal axis of the graph in Figure 12 is the x-axis, which represents the applied voltage x [V] applied to the second electrode 42. The vertical axis of the graph in Figure 12 is the y-axis, which represents the phase difference y [radians] with respect to the initial phase. The first electrode 41 was grounded, and the voltage applied to the second electrode 42 was varied from 0V to 125V. The phase at the output end was measured, and the phase difference from the phase obtained when no voltage was applied was determined. Measurement points for Example 1 are shown as black circles, and measurement points for the comparative example are shown as white circles.

[0085] The approximate phase control formula obtained from the comparative example was y = 0.0143x. On the other hand, the approximate phase control formula obtained from the results of Example 1 was y = 0.0216x. Therefore, the optical modulation efficiency of Example 1 was 1.5 times that of the comparative example. According to these simulation results, it is considered that the optical modulation efficiency of Example 1 was improved because the structure has a tapered structure at the end of the first core 11 where different cores are connected, and the optical modulation section 4 does not use a SiN core (first core 11) that does not contribute to optical modulation.

[0086] Furthermore, the inventors of this application confirmed the effect of the optical deflection element 1B by optical output simulation, and will explain this with reference to Figure 13 (and other drawings such as Figures 8 and 10 as appropriate). The structure shown in Figure 13(a) is designated as Example 2. Note that the same conditions as those in Example 1 will not be explained, and the differences from Example 1 will be explained mainly. The structure shown in Figure 13(a) is almost the same as the structure shown in Figure 10(a), however, the core connection peripheral portion 82 shown in Figure 13(a) differs from the core connection peripheral portion 81 shown in Figure 10(a). Figure 13(b) shows an enlarged view of the core connection periphery 82 shown in Figure 13(a), viewed from above through the cladding. The differences in materials, refractive index, and scale of each part of Example 2 compared to Example 1 are as follows. Note that in each drawing, the length, width, and thickness are exaggerated to make the characteristics of the members easier to understand.

[0087] <Core connection sections 8, 9 (however, size of the first core)> Core connection width: 0.5 μm (constant) Core connection length: 16.68 μm Distance between the top surface of the first core and the bottom surface of the second core at the core connection point: 0.3 μm (same) <Adjacent regions 78, 79 (however, this is the size of the first core)> Width at the point where the taper of the adjacent region begins: 1.0 μm Width at the tapered tip position of the adjacent region: 0.5 μm Taper length (length of adjacent region): 130 μm

[0088] Figure 13(c) shows the optical output simulation results for Example 2. The simulation was performed using OptiBPM from Optiwave. As shown in the figure, when the input optical intensity is 1, the output obtained at the output terminal is 0.9, and the output ratio to input (output / input) is 90%. Example 2 shows that a high-efficiency output with a coupling efficiency of 90% can be obtained by applying a tapered structure and a straight waveguide to the core connection peripheral part 82. [Explanation of Symbols]

[0089] 1,1B Light deflection element 2 Light incidence part 3,3A optical distribution section 4,4B Optical Modulation Section 5. Light-emitting section 6. Introduction 8,9 Core connection section 10 Optical waveguide 11. First Core 11e End face 12 Second Core 21, 21B, 22, 22B Core connection peripheral area 31 Circuit board (First circuit board) 32 Clad 32a Lower cladding 32b Middle layer 32c upper clad 41,41C,41E 1st electrode 42,42D 2nd electrode 50. First layer 61 Second board 62 Planar core 63. Second layer 64,65 Core connection peripheral area 78,79 Adjacent regions 81,82 Core connection peripheral area

Claims

1. An optical deflection element comprising a plurality of optical waveguides on a substrate, each having an optical modulation section for modulating incident light and an optical emission section for emitting the modulated light, Each core of the optical waveguide comprises a first core located in the light emission section and a second core located in the optical modulation section, which is made of a refractive index changing material having a refractive index smaller than that of the first core. The first core and the second core are discontinuous at least between the light modulation section and the light emission section, and the first core and the second core have a core connection section that overlaps in a plan view in the longitudinal direction of the core. The optical deflection element is characterized in that, in the core connection portion, the first core and the second core are stacked vertically in the thickness direction of the substrate and are in contact with or in close proximity to each other.

2. Each core of the optical waveguide is discontinuous between the introduction section that introduces incident light to the optical modulation section and the optical modulation section. The optical deflection element according to claim 1, characterized in that the first core is arranged in the light emission section and the light introduction section.

3. The optical deflection element according to claim 1 or 2, characterized in that the first core is formed of an inorganic material and the second core is formed of an organic material.

4. The first core is Si 3 N 4 , Si, LiNbO 3 , and Nb 2 O 5 It is made of one material selected from the group consisting of, The second core is made of one material selected from the group consisting of an EO polymer, LiNbO 3 , LiTaO 2 , and Al 2 O 3 The optical deflection element according to claim 1 or claim 2, characterized in that it is formed of one material selected from the group consisting of.

5. The optical deflection element according to claim 4, characterized in that the optical modulation section does not have the first core.

6. The second core is Si, Si 3 N 4 The optical deflection element according to claim 1 or 2, characterized in that it is formed of one material selected from the group consisting of , and InP.

7. The optical deflection element according to any one of claims 1 to 6, characterized in that the first core has an end face at the core connection portion, and at the core connection portion, the first core is formed in a tapered shape with the core width in a plan view tapering toward the end face.

8. The optical deflection element according to any one of claims 1 to 6, characterized in that the first core has an end face at the core connection portion, the width of the first core is minimum and constant at the core connection portion, and in an adjacent region adjacent to the core connection portion, the first core is formed in a tapered shape in plan view, with the core width tapering toward the core connection portion.

9. A method for manufacturing an optical deflection element comprising a plurality of optical waveguides on a substrate, each having an optical modulation section for modulating incident light and an optical emission section for emitting modulated light, wherein the core of each optical waveguide is discontinuous at least between the optical modulation section and the optical emission section, A step of forming a first laminate comprising a first substrate, a lower cladding on the first substrate, a plurality of first cores made of a material having a first refractive index and formed in parallel in a predetermined pattern in a region on the lower cladding that will become the light-emitting portion, and an intermediate layer that fills the gaps between the first cores, A second laminate formation step involves performing a polling process on a planar core made of a core material having a second refractive index smaller than the first refractive index, thereby forming a second laminate comprising a second substrate and a planar core that has been subjected to the polling process and is laminated in a predetermined region on the second substrate. A transfer step in which a planar core on the second laminate is bonded to the region of the first laminate that will become the optical modulation portion, and the planar core is transferred to the first laminate by peeling off the second substrate, The process includes a second core forming step of forming a plurality of second cores by dividing the planar core transferred to the first laminate according to the pattern of the plurality of first cores, The method for manufacturing an optical deflection element, characterized in that the transfer step is performed such that the plurality of first cores and the planar cores have core connection portions that overlap in a plan view in the longitudinal direction of the cores, and are in contact with or in close proximity to each other.

10. The method for manufacturing an optical deflection element according to claim 9, further comprising an upper cladding formation step of forming an upper cladding that covers the intermediate layer and the plurality of second cores.

11. A method for manufacturing an optical deflection element according to claim 9 or 10, further comprising a phase shifter formation step of forming a plurality of phase shifters made of a conductive material and aligned with the pattern of the first core at either the timing before or after the transfer step.

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