JP6325941B2 - Optical circuit - Google Patents

Description

  The present invention relates to an optical circuit having an optical waveguide through which an optical signal propagates, and more particularly, to an optical circuit including a grating coupler for inputting and outputting light.

  2. Description of the Related Art Planar lightwave circuits using Si as an optical waveguide core (Si optical circuit) are attracting attention as a platform capable of integrating various optical functions in a small size and at low cost. One of the problems in the Si optical circuit is realization of high-efficiency optical coupling efficiency with external optical elements such as an optical fiber, a photodiode (PD), or a laser diode (LD) in the optical input / output unit.

  In a conventional Si optical circuit, a method of arranging a grating coupler in the optical circuit and inputting / outputting in a direction perpendicular to the substrate surface is widely used as a form of light input / output. For high-efficiency optical coupling efficiency, Non-Patent Document 1 discloses that high-efficiency coupling with an optical fiber coupling loss of about 0.6 dB can be obtained by optimizing the grating shape. Non-Patent Document 2 proposes a configuration that combines the functions of input / output and polarization separation / combination by actively utilizing the polarization dependence of the coupling characteristics.

  Since the above-described grating coupler radiates light on both the upper and lower sides, it is difficult to make the optical coupling with an external element highly efficient. For this reason, a configuration is known in which a reflective film is provided on either one of the upper and lower sides of the grating coupler to collect the emitted light in one direction. Non-Patent Document 3 proposes a structure in which a Si optical circuit is bonded to a wafer on which gold (Au) is deposited.

  Patent Document 1 proposes a configuration in which a reflective film is deposited on a window formed from the back surface of a Si substrate. Further, Patent Document 2 proposes a configuration in which a reflective film is deposited on the upper surface of the Si optical circuit and a light extraction window is formed from the rear surface of the Si substrate. In addition, about the nonpatent literature 1, the structure similar to the said structure of the patent document 1 is employ | adopted.

JP2011-203604A JP 2012-208371 A

W.S.Zaoui et al., “CMOS-Compatible Nonuniform Grating Coupler with 86% Coupling Efficiency,” in Proc. ECOC2013, paper Mo.3.B.3. C.R.Doerr et al., “Monolithic Silicon Coherent Receiver,” Proc. OFC / NFOEC2009, paper PDPB2. F.V.Laere et al., “Compact and Highly Efficient Grating Couplers Between Optical Fiber and Nanophotonic Waveguides”, Jounal of Lightwave Technology Vol.25, No.1, January 2007, pp.151-156

  In the case of Non-Patent Document 2, although the grating coupler is manufactured by a simple process that does not use a complicated process such as wafer bonding or window formation on the back surface, there is a problem that the optical coupling efficiency is lowered.

  In the case of Non-Patent Document 3, there is a problem that the manufacturing process becomes complicated. That is, in addition to a normal Si optical circuit manufacturing process, a wafer bonding process and a supporting silicon layer removing process on the optical circuit side are required.

  Also, in the case of Patent Documents 1 and 2, there is a problem that a window forming process from the back surface of the Si substrate is required, and the manufacturing process becomes complicated.

  The present invention has been made in such a situation, and an object thereof is to provide an optical circuit having an optical input / output structure with high efficiency and a simple manufacturing process.

The present invention for solving the above problems, a support substrate having an inclined structure, an under cladding layer formed on the support substrate, a core layer formed on the under cladding layer and having a grating coupler, An over clad layer formed on the core layer, the under clad layer is not in contact with the support substrate below the grating coupler, and the inclined structure is formed on the support substrate below the grating coupler. The inclined structure reflects light emitted from the grating coupler .

  Here, a reflective film may be formed on the over clad layer above the grating coupler.

A matching material having a refractive index comparable to that of the under cladding layer may be filled between the under cladding layer below the grating coupler and the inclined structure.

  The material of the support substrate and the core layer may be Si, and the material of the under cladding layer may be SiO2.

The inclined structure may be formed by anisotropic etching with respect to the support substrate.

Further, the present invention for solving the above problems is a method for manufacturing an optical circuit, wherein an under cladding layer, a core layer having a grating coupler, and an over cladding layer are stacked in this order on a support substrate. A step of forming an optical waveguide; a step of removing the overcladding layer and the undercladding layer in a peripheral portion of the grating coupler to form a groove; and a masking of the overcladding layer and the undercladding layer of the grating coupler. And forming an inclined structure for reflecting light emitted from the grating coupler on the support substrate below the grating coupler by anisotropically etching the groove .

  According to the present invention, the manufacturing process is highly efficient and simple.

It is a figure for demonstrating the outline | summary structure of the optical circuit in 1st Embodiment. It is a figure which shows an example of the manufacturing process of the slope structure of an optical circuit. It is the schematic which shows the structural example of the optical circuit of 2nd Embodiment. It is the schematic which shows the structural example of the optical circuit of 3rd Embodiment. In the optical circuit of 3rd Embodiment, it is a schematic diagram which shows a mode that light propagates by an inclined structure. It is a schematic diagram which shows the modification of the optical circuit of 1st Embodiment.

<First Embodiment>
The optical circuit 10 according to the first embodiment of the present invention will be described below.

[Configuration of optical circuit]
First, the configuration of the optical circuit 10 of the present embodiment will be described with reference to FIG. 1A and 1B are schematic diagrams illustrating a configuration example of an optical circuit 10 according to the present embodiment, in which FIG. 1A is a top view of the optical circuit 10, and FIG. 1B is a cross-sectional view taken along line AA ′ illustrated in FIG. Indicates.

The optical circuit 10 includes a support substrate 100 made of, for example, Si. As shown in FIG. 1B, in the optical circuit 10, an under clad layer 101, a core layer 102, and an over clad layer 103 are laminated on the support substrate 100 from the support substrate 100 side. In the optical circuit 10, two cladding layers 101 and 103 are formed, for example, SiO _2, the core layer 102 is formed, for example, Si.

  Note that the support substrate 100 shown in FIG. 1 may be formed of, for example, quartz.

  In FIG. 1, the core layer 102 includes a grating coupler 111 and an input / output optical waveguide 112 optically connected to the grating coupler 111.

  On the over clad layer 103 above the grating coupler 111, a reflective film 113 made of, for example, Al is formed. Further, the support substrate 100 has an inclined surface structure 121 below the grating coupler 111.

  The under cladding layer 101 is not in contact with the support substrate 100 under the grating coupler 111.

  In the present embodiment, the plane orientation of the Si support substrate 100 is (100). The slope structure 121 is a Si (111) surface formed by anisotropic wet etching, as will be described later. The angle θs of the slope of the slope structure 121 with respect to the horizontal plane is 54.7 °.

A matching material having a refractive index close to that of SiO ₂ that is the material of the under cladding layer 101 is provided between the under cladding layer 101 below the grating coupler 111 and the slope structure 121 in order to prevent light reflection on the lower surface of the under cladding layer 101. 141 is filled. As the matching material 141, an adhesive or the like used for connecting the optical circuit 10 and the optical fiber 142 can be used.

  The light emitted downward from the grating coupler 111 is reflected by the inclined surface structure 121, emitted in the surface direction on the support substrate 100 side, and coupled to the optical fiber 142.

  In this optical circuit 10, since the reflective film 113 is formed, almost all of the light emitted from the grating coupler 111 is emitted below the grating coupler 111 as shown by the arrow in FIG. The The light emitted downward changes its optical path direction in a substantially horizontal direction (positive z-axis direction) due to reflection by the slope structure 121, and then couples to the optical fiber 142.

  When the light emission angle θb (that is, the angle of light emitted from the grating coupler 111 with respect to the −y-axis direction) shown in FIG. 1B is θb = 2θs−90 °, the light reflection by the inclined surface structure 121 is performed. The later outgoing optical axis can be set in the horizontal direction (z-axis direction) with respect to the substrate surface of the support substrate 100.

  In the example of FIG. 1B, θb for obtaining horizontal emission is θb = 19.5 °. Since the value of θb depends on the grating pitch, it can be adjusted at the time of design.

[Optical circuit fabrication process]
Next, the overall manufacturing process of the optical circuit 10 of this embodiment will be described again with reference to FIG.

  In this manufacturing process, first, a Si optical circuit having an optical waveguide and a grating coupler is manufactured.

For example, first, an SOI (Silicon on Insulator) substrate is prepared in which an Si (100) substrate as the support substrate 100, an SiO ₂ layer as the under cladding layer 101, and an Si layer as the core layer 102 are stacked in this order. In this case, the thickness of the support substrate 100 is, for example, 500 μm, the thickness of the under cladding layer 101 is, for example, about 2 μm, and the thickness of the core layer 102 is, for example, about 250 nm.

  Subsequently, a resist pattern for defining the optical waveguide shape is formed on the core layer 102 by photolithography, and etching is performed by an RIE (Reactive Ion Etching) method or the like. In this case, in order to form the grating coupler 111, the etching process is performed in two or more stages.

  For example, about 80 nm is dug while leaving the convex portion of the grating coupler 111 by the first etching, and the core layer 102 is removed leaving all the optical waveguide portions including the grating coupler 111 by the second etching.

  The length of the grating coupler 111 in the light propagation axis direction is, for example, about 20 μm.

Finally, an overcladding layer 103 made of SiO ₂ is deposited by plasma CVD (Chemical Vapor Deposition) or the like, and the upper surface thereof is flattened by CMP (Chemical Mechanical Polishing) or the like. The thickness of the over clad layer 103 is about 2 μm, for example. In this manner, a Si optical circuit having the optical waveguide 112 and the grating coupler 111 is manufactured.

  Further, in the optical circuit 10 of this embodiment, a reflective film 113 is formed. As the material of the reflective film 113, for example, Al is used. For the pattern formation of the reflective film 113, for example, photolithography and plasma CVD can be employed as in the case of optical waveguide formation.

The thickness of the Al film of the reflective film 113 is about 500 nm, for example. After the formation of the reflective film 113, a protective film such as SiO ₂ is formed on the reflective film 113 as necessary.

  When it is necessary to form an electrical wiring in the Si optical circuit, Al is often used as the material of the electrical wiring. Therefore, it is preferable to use the above-described Al as the material of the reflective film 113. This is because the formation of the wiring and the formation of the reflective film can be performed at the same time, and as a result, the production efficiency is good.

  As a case where it is necessary to form an electrical wiring in the Si optical circuit, for example, in an optical circuit including a phase shifter using a thermo-optic effect or a carrier effect, a wiring for extracting an electrode is required. .

  In each of the above steps, the thickness of each layer, the number of steps in the etching step, the depth of digging, and the like can be appropriately changed according to desired characteristics.

  Further, when a finer pattern is required in forming a resist pattern, electron beam lithography can be used.

  As the material of the over clad layer 103, SiON, polymer, or the like may be used. For example, Au may be used as the material of the reflective film 113. Further, vacuum deposition may be applied for the deposition of the reflective film 113, and a lift-off method may be applied for patterning.

[Slope structure manufacturing process]
Next, a manufacturing process of the slope structure 121 described above will be described with reference to FIG. 2A and 2B are diagrams illustrating an example of a manufacturing process of the slope structure 121 of the optical circuit 10, where (1) is a process of forming the groove 231 around the grating coupler 211 and the reflective film 213, and (2) is the groove 231. A step of forming the inclined structure 221 by dicing the substrate.

  First, a U-shaped groove 231 is formed in the peripheral portion of the grating coupler 111 and the reflective film 113 (FIG. 2 (1)). Specifically, the over-cladding layer 103 and the under-cladding layer 101 are etched away by photolithography and RIE using the support substrate 100 as an etch stopper, thereby forming a groove 131 as shown in FIG.

  The outer shape of the groove 131 is, for example, 70 μm (x-axis direction) × 80 μm (z-axis direction) (see the top view of FIG. 2A). The size of each U-shaped overhang (projection) of the groove 131 is, for example, 30 μm (x-axis direction) × 40 μm (z-axis direction) (see the top view of FIG. 2A). ).

  The step of forming the groove 231 can be performed simultaneously with the formation of the heat insulation groove, for example, when it is necessary to form the heat insulation groove for improving the power efficiency of the thermo-optic phase shifter.

Next, etch pits are formed by performing anisotropic wet etching with a KOH aqueous solution using the SiO ₂ film as the over clad layer 103 and the under clad layer 101 as a mask. Due to the dependency of the etching rate on the Si plane orientation, the lower part of the overhang is undercut to form a frustum-shaped etch pit along the outer diameter of the groove 131 (for example, KEPetersen, Silicon as a Mechanical Material, Proc IEEE, vol. 70, no. 5, May. 1982, pp. 420-457 (see FIG. 5 (d)).

  In the present embodiment, the slope structure 121 corresponding to the Si (111) plane can be obtained below the grating coupler 111. In this case, the angle of the slope of the slope structure 121 is, for example, 54.7 °.

  Next, as shown in FIG. 2 (2), the slope structure 121 having θ shown in FIG. 2 (2) is obtained by cutting it off by dicing or the like on the left side from the center of the groove 131 (below the grating coupler 111). Can be obtained.

  The structure of the optical circuit 10 of the present embodiment does not require special processes (wafer bonding, processing from the back surface) as in the conventional case, and general processing (film formation, photolithography, etching) from the top surface of the wafer. ) Only. For this reason, the optical circuit 10 is easier to manufacture than the conventional circuit.

  Further, in the optical circuit 10, since the reflective film 113 is formed on one side of the grating coupler 111, highly efficient optical coupling with an external element (in this embodiment, the optical fiber 142) can be realized.

Second Embodiment
Hereinafter, an optical circuit 10A according to the second embodiment will be described.

  In the optical circuit 10 of the first embodiment, the orientation of the grating coupler 111 may be changed and arranged. That is, in the optical circuit 10 of the first embodiment, the grating coupler 111 is arranged in parallel (z-axis direction) to the final emission direction reflected by the inclined surface structure 121, but the optical circuit of the present embodiment. In 10A, the grating coupler 311 is arranged so as to be orthogonal to the emission direction (x-axis direction).

  The direction of the grating coupler 111 described above means the light propagation direction in the grating coupler.

  The configuration of the optical circuit 10A other than the above is almost the same as that shown in FIGS. In the following description of the present embodiment, the terms used in the description of the first embodiment are used as they are unless otherwise specified.

  3A and 3B are schematic diagrams illustrating a configuration example of the optical circuit 10A according to the present embodiment, in which FIG. 3A is a top view of the optical circuit 10A, and FIG. 3B is a cross-sectional view taken along line AA ′ illustrated in FIG. Indicates.

  As shown in FIG. 3, in the optical circuit 10A, similarly to the one shown in FIG. 1, an under cladding layer 301, a core layer 302, and an over cladding layer 303 are stacked on a support substrate 300. A grating coupler 311 and an input / output optical waveguide 312 are included. A reflective film 313 is formed on the over clad layer 303 above the grating coupler 311, and a slope structure 321 is provided below the grating coupler 311.

The matching material 341 is an adhesive having a refractive index close to that of SiO ₂ that is a material of the under cladding layer 301 in order to prevent light reflection between the under cladding layer 301 and the inclined structure 321 on the lower surface of the under cladding layer 301. Etc. are formed.

  On the other hand, unlike the one shown in FIG. 1, in this optical circuit 10A, the grating coupler 311 is arranged so that the light propagation direction in the grating coupler 311 is in the x-axis direction. In this case, the angle θs of the slope structure 321 is 45 °, and therefore the outgoing beam tilt angle θb in the yz plane from the grating coupler 311 is 0 °.

  Note that the 45 ° slope of the inclined structure 321 can be formed using a Si (110) substrate and an Si (100) plane as the slope.

  The light emitted downward from the grating coupler 311 is reflected by the slope structure 321 and emitted in the surface direction on the support substrate 300 side. As a result, a waveguide type SSC (Spot (Spot)) serving as an input / output unit of the planar optical waveguide element 343 is obtained. -Size Converter) coupled to optical fiber 344.

  In general, in the waveguide type SSC, it is easy to control the mode shape in the horizontal direction with respect to the substrate of the planar optical waveguide device, but it is difficult to control the mode shape in the substrate vertical direction. This is because the mode shape in the horizontal direction can be controlled by the mask pattern shape, for example, the width of the SSC, but the mode shape in the vertical direction is basically defined by the film forming conditions such as the core film thickness. This is because the degree of freedom in design is not high due to restrictions such as circuit elements.

  On the other hand, with respect to the mode shape of the input / output beams of the grating coupler, mode control in the direction orthogonal to the light propagation axis direction in the grating (x-axis direction in FIG. 1 and z-axis direction in FIG. 3) is easy and parallel Control of the mode shape in the z-axis direction in FIG. 1 and the x-axis direction in FIG. 3 becomes difficult. This is because the mode shape in the orthogonal direction can be controlled by a mask pattern shape, for example, the lateral width of the grating coupler section, and further, it can be condensed by using a curved grating (for example, FVLaere et al., “Compact Focusing Grating Couplers for Silicon-on-Insulator Integrated Circuits,” Photon. Technol. Lett., Vol.19, no.23, December 2007, pp. 1919-1921), but the parallel mode shape is Because it is defined by the scattering intensity of each irregularity of the grating, and the scattering intensity is basically determined by the depth of each irregularity, it is difficult to control the mode shape unless special and complicated processes such as multi-step etching are used. is there.

  In addition to the effects of the first embodiment (highly efficient optical coupling can be achieved with a simple manufacturing process), the optical circuit 10A of the present embodiment also has the following effects. That is, depending on the orientation of the grating 311, the horizontal mode (x-axis direction) mode shape of the SSC 344 on the planar optical waveguide device side is designed to match the mode shape of the grating coupler 311 in the propagation axis parallel direction (x-axis direction). Furthermore, since the mode shape of the grating coupler 311 in the direction orthogonal to the propagation axis (z-axis direction) can be matched to the mode shape of the SSC 344 in the vertical direction (y-axis direction), high optical coupling efficiency can be realized.

<Third Embodiment>
The shape of the slope structure 141 shown in FIG. 1 can be changed. 4A and 4B are schematic diagrams illustrating a configuration example of the optical circuit 10B according to the present embodiment, in which FIG. 4A is a top view of the optical circuit 10B, and FIG. 4B is a cross-sectional view taken along the line AA ′ illustrated in FIG. Indicates.

  As shown in FIG. 4, in the optical circuit 10B, similarly to the one shown in FIG. 1, an under cladding layer 401, a core layer 402, and an over cladding layer 403 are stacked on a support substrate 400. A grating coupler 411 and an input / output optical waveguide 412 are provided. A reflective film 413 is formed on the over clad layer 403 above the grating coupler 411, and a slope structure 421 is provided below the grating coupler 411.

The matching material 441 is formed of an adhesive material having a refractive index close to that of SiO ₂ that is the material of the under cladding layer 301.

  On the other hand, unlike the one shown in FIG. 1, in this optical circuit 10B, the slope structure 421 uses a Si (111) surface. In the example of FIG. 4, θb is, for example, 54.7 °. The inclined structure 421 includes two inclined structures 421 and 422 as shown in FIG.

  In the optical circuit 10B of this embodiment, the light emitted from the grating coupler 411 is reflected by the inclined structure 421, then further reflected by the inclined structure 422, and emitted above the support substrate 400 (+ y-axis direction). In this case, if an external element (for example, an optical fiber, a photodiode, a laser diode, or the like) on which the emitted light is incident is disposed above the substrate 100, highly efficient optical coupling is realized.

  Although the external element is not shown in FIG. 4, the matching material 441 is preferably filled also between the external element to be bonded and the over clad layer 403.

  The manner in which light propagates through the inclined structures 421 and 422 will be described with reference to FIG. FIG. 5 is a schematic diagram illustrating how light propagates through the inclined structures 421 and 422.

  In FIG. 5, assuming that the outgoing beam tilt angle downward from the grating coupler 411 in the yz plane is θb and the tilt angles of the slope structures 421 and 422 are θs, the beam angle finally emitted from the optical circuit 10B is ( −θb + 4θs−180) °. From this equation, for example, when the beam angle finally emitted is 8 °, θb may be about 30.1 °.

  The optical circuit 10B of the present embodiment is useful when performing optical input / output in the vertical direction (y-axis direction). In the structure of the optical circuit 10B, since the beam propagation distance between the grating coupler 411 and the external element becomes longer than that shown in the first embodiment, the coupling loss due to beam spreading can be slightly increased. However, the reflection film 413 increases the collection efficiency of the emitted light from the grating coupler 411. In this respect, as in the case of the first embodiment, there is an effect that it can be realized by a highly efficient and simple manufacturing process.

  As mentioned above, although each said embodiment was explained in full detail, the structure of optical modulator 10, 10A, 10B can also be changed.

  For example, in the optical circuit 10 of the first embodiment, the coupling-destination external element is not limited to the optical fiber 142, and may be, for example, a laser diode, a photodiode, or another optical waveguide. The grating coupler 111 has a degree of design freedom, and various optimum designs are possible according to the waveguide mode shape of the external element.

  The final optical axis from which light is emitted by reflection by the slope structure 121 of the first embodiment does not necessarily have to be parallel to the z-axis. For example, in the case of using an optical fiber block whose end is polished obliquely, the outgoing optical axis may be inclined in the yz plane. In that case, it is not necessary to satisfy the above θb = 2θs−90 °.

  In the optical circuit 10 of the first embodiment, the case where the Si (100) substrate 100 is used and the Si (111) surface is the sloped structure 121 has been described, but Si (110) is used as the substrate 100 and Si (100). The surface may be a slope structure 121. In this case, a slope structure with an angle θs = 45 ° can be obtained (for example, Yamashita et al., Isotropic etching of n-Si (110) by voltage application using a KOH aqueous solution, Denso Technical Review, Vol. 6). , No. 2, 2001).

  In the optical circuit 10 of the first embodiment, the case where the reflective film 113 is formed has been described. However, the reflective film 113 may be omitted. FIG. 6 is a schematic diagram showing a configuration example of the optical circuit 10a.

  In the optical circuit 10 a shown in FIG. 6, no reflective film is formed above the grating coupler 111. In the example of FIG. 6, light emitted from the grating coupler 111 is extracted from both above (+ y-axis direction) and side (+ z-axis direction), and each direction component is used. That is, as shown in FIG. 6, the input / output fiber 142 is provided above the optical circuit 10a, and the monitoring photodetector 650 is provided on the side surface of the optical circuit 10a.

  If, in the conventional structure (Non-patent Document 3), as in the case shown in FIG. 6, it is attempted to use both outputs on both sides of the grating coupler, the upper (+ y-axis direction) and the lower (− The element must be arranged at the input / output destination with respect to the y-axis direction), and as a result, it is difficult to mount. However, as shown in FIG. 6, by forming the slope structure 121 below the grating coupler 111, light input / output can be performed from above and from the side, not from the top and bottom surfaces of the optical circuit.

  In the optical circuit 10A of the second embodiment, the case where the angle θs of the slope structure 321 is, for example, 45 ° has been described. However, the value of θs can be changed. For example, when θs is set to 54.7 °, the grating pattern of the grating coupler 311 is provided obliquely so that the tilt angle of the outgoing beam from the grating coupler 311 is set to 19.5 °. It is preferable to shift the in-plane arrangement direction by a predetermined angle from the x-axis direction instead of the x-axis direction.

  Further, in the optical circuit 10A of the second embodiment, assuming that the tilt angle of the outgoing beam in the xy plane from the grating coupler 311 is 0 °, the direction of the SSC 344 is made parallel to the z-axis direction. However, when the tilt angle of the outgoing beam is not 0 °, the SSC 344 is also preferably arranged so as to have a predetermined tilt with respect to the z-axis direction.

10
100, 300, 400 Support substrate 101, 301, 401 Under clad layer 102, 302, 402 Core layer 103, 303, 403 Over clad layer 111, 311, 411 Grating coupler 112, 312, 412 Optical waveguide 113, 313, 413 Reflection Films 121, 421, 422 Slope structure 141, 341, 441 Matching material 142 Optical fiber 343 Planar optical waveguide element 344 Waveguide SSC

Claims (6)

A support substrate having an inclined structure; an underclad layer formed on the support substrate;
A core layer formed on the under cladding layer and having a grating coupler;
An overcladding layer formed on the core layer,
The under cladding layer is not in contact with the support substrate under the grating coupler,
2. The optical circuit according to claim 1 , wherein the inclined structure is formed on the support substrate below the grating coupler, and has an inclined structure that reflects light emitted from the grating coupler .   The optical circuit according to claim 1, wherein a reflection film is formed on the over clad layer above the grating coupler. 3. A matching material having a refractive index comparable to that of the under cladding layer is filled between the under cladding layer and the inclined structure below the grating coupler. An optical circuit according to 1. The material of the support substrate and the core layer is Si,
Optical circuit according to any one of claims 1 to 3 material of the under-cladding layer is characterized by a SiO _2. The optical circuit according to claim 4, wherein the inclined structure is formed by anisotropic etching with respect to the support substrate. An optical circuit manufacturing method comprising:
On the support substrate, forming an optical waveguide laminated in the order of an under cladding layer, a core layer having a grating coupler, and an over cladding layer;
In the peripheral portion of the grating coupler, removing the over clad layer and the under clad layer to form a groove;
Using the over-cladding layer and under-cladding layer of the grating coupler as a mask, the groove is anisotropically etched to provide an inclined structure that reflects light emitted from the grating coupler on the support substrate under the grating coupler. And a forming method.

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