Wavelength combiner / splitter, method for manufacturing wavelength combiner / splitter, design device, computer readable storage medium, and demultiplexer

Abstract

The invention provides a multiplexer / demultiplexer, a method of manufacturing the multiplexer / demultiplexer, a design device, a computer-readable storage medium, and a demultiplexer, which can obtain desired characteristics. A method for manufacturing a multiplexer / demultiplexer having a substrate, and a first port for inputting light and a second port for outputting light, the first port and the second port being provided on the substrate, the manufacturing method comprises the following steps: designing the positions of the plurality of holes in a manner that three adjacent holes are arranged in a triangular lattice shape; and forming the plurality of holes in one surface of the substrate.

Description

Technical Field

[0001] The invention relates to a wavelength combiner and demultiplexer and a manufacturing method thereof, a design device, a computer-readable storage medium and a demultiplexer. Background Art

[0002] Mosaic-shaped optical passive components are being developed. By arranging a plurality of holes in a plane, light is branched at a predetermined intensity ratio and a compact wavelength multiplexing / demultiplexing device is formed (Non-Patent Document 1, etc.).

[0003] Prior art literature Non-patent literature Non-patent document 1: "Compact Power Splitters with Mosaic-based StructureDesigned by Bayesian Direct-binary-search Method" Takuya Mitarai et. al. inProc. OECC / PSS 2022, Toyama, Japan, Aug. 2022, TuE2-4 Summary of the invention Problems to be solved by the invention In the manufacturing process, the hole configuration is designed and the holes are formed by dry etching in the silicon layer. Sometimes the walls between the holes become thinner due to manufacturing errors, etc. Sometimes the walls disappear and the holes are coupled to each other as one. In this case, there is a risk of deterioration of characteristics. Therefore, the purpose of the present invention is to provide a wavelength combiner / demultiplexer that can obtain desired characteristics, and a manufacturing method, design device, computer-readable storage medium, and demultiplexer.

[0004] Means used to solve problems The manufacturing method of the wavelength combiner / demultiplexer involved in the present invention is a manufacturing method of the wavelength combiner / demultiplexer having a substrate, a first port for inputting light, and a second port for outputting light, which are arranged on the substrate. The manufacturing method of the wavelength combiner / demultiplexer has the following steps: designing the positions of the multiple holes in such a way that three adjacent holes are arranged in a triangular lattice; and forming the multiple holes on one surface of the substrate.

[0005] Effects of the Invention According to the present invention, a wavelength multiplexer / demultiplexer capable of obtaining desired characteristics, a manufacturing method thereof, a design device, a computer-readable storage medium, and a demultiplexer can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1A It is a top view showing an example of the wavelength multiplexing / demultiplexing device according to the first embodiment.

[0007] Figure 1B This is an enlarged top view of the hole.

[0008] Figure 2A 1 is a cross-sectional view showing an example of a wavelength multiplexing / demultiplexing device.

[0009] Figure 2B 1 is a cross-sectional view showing an example of a wavelength multiplexing / demultiplexing device.

[0010] Figure 3A This is a block diagram showing an example of a design device for a wavelength multiplexer / demultiplexer.

[0011] Figure 3B This is a block diagram showing the hardware configuration of the control unit.

[0012] Figure 3C The flowchart exemplifies a method for manufacturing a wavelength multiplexer / demultiplexer.

[0013] Figure 3D The flowchart exemplifies a method for manufacturing a wavelength multiplexer / demultiplexer.

[0014] Figure 4 The diagram is a plan view showing an example of a method for manufacturing a wavelength multiplexing / demultiplexing device.

[0015] Figure 5A The cross-sectional view exemplifies a method for manufacturing a wavelength multiplexing / demultiplexing device.

[0016] Figure 5B The cross-sectional view exemplifies a method for manufacturing a wavelength multiplexing / demultiplexing device.

[0017] Figure 5C The cross-sectional view exemplifies a method for manufacturing a wavelength multiplexing / demultiplexing device.

[0018] Figure 6 2 is a diagram showing an example of a branching ratio.

[0019] Fig. 7A This is an enlarged plan view of a hole in a wavelength multiplexing / demultiplexing device according to a comparative example.

[0020] Figure 7B This is an enlarged plan view of a hole in a wavelength multiplexing / demultiplexing device according to a modified example.

[0021] Figure 8 It is a top view showing an example of the wavelength multiplexing / demultiplexing device according to the second embodiment.

[0022] Fig. 9 It is a top view showing an example of a wavelength multiplexing / demultiplexing device according to the third embodiment.

[0023] Fig.10 It is a top view showing an example of the wavelength multiplexing / demultiplexing device according to the fourth embodiment.

[0024] Fig.11 2 is a diagram showing an example of a branching ratio.

[0025] Fig.12 It is a top view showing an example of a demultiplexer according to the fifth embodiment.

[0026] Fig.13 It is a graph which shows transmittance as an example.

[0027] Description of Reference Numerals 1: incident port; 2: output port; 10, 12: substrate; 14: buried oxide layer; 15: waveguide core; 16: Silicon layer; 17: Platform; 20, 20a, 20b, 20c, 22, 22a, 22b, 22c, 24, 24a, 24b, 24v: port; 30: hole; 32, 32a, 32b: area; 34: wall; 40: resist; 42: opening; 50: Control department; 51: First Design Department; 52: Second Design Department; 54: CPU; 56: RAM; 58: ROM; 60: storage device; 62: interface; 100, 200, 300, 400, 510, 520, 530: wavelength combiner and splitter; 110: Design device; 500: Demultiplexer. DETAILED DESCRIPTION

[0028] [Description of Embodiments of the Invention] First, the contents of the embodiments of the present invention will be listed and described.

[0029] One aspect of the present invention is to provide (1) a method for manufacturing a wavelength combiner / demultiplexer, which comprises a substrate, a first port for inputting light, and a second port for outputting light, which is arranged on the substrate, wherein the manufacturing method comprises the following steps: designing the positions of the plurality of holes in such a way that three adjacent holes among the plurality of holes are arranged in a triangular lattice; and forming the plurality of holes on one surface of the substrate. The walls between adjacent holes become thicker and less prone to damage. Adjacent holes are less prone to coupling and are separated from each other. By setting the designed number and layout of holes, the desired characteristics can be obtained.

[0030] (2) In the above (1), the designing step may include the following steps: dividing the surface of the substrate into a plurality of regions arranged in a triangular lattice; and arranging the holes in a portion of the plurality of regions and not arranging the holes in another portion of the plurality of regions. The wall becomes thicker and the plurality of holes are separated. The desired characteristics can be obtained.

[0031] (3) In the above (2), the planar shape of the region may be a regular hexagon, and the step of dividing the surface of the substrate into a plurality of regions includes the step of arranging the plurality of regions in a closest packing structure. The wall becomes thicker and the plurality of holes are separated. The desired characteristics can be obtained.

[0032] (4) In any one of (1) to (3) above, the designing step may be a step of designing the positions of the plurality of holes based on the characteristics of the multiplexer / demultiplexer. A multiplexer / demultiplexer having a triangular lattice arrangement and desired characteristics can be manufactured.

[0033] (5) In any one of (1) to (4) above, the step of forming the plurality of holes may include forming the holes by dry etching the silicon layer of the substrate. The plurality of holes are separated due to the wall thickness, and the desired characteristics can be obtained.

[0034] (6) In any one of (1) to (5) above, the method for manufacturing a wavelength multiplexing / demultiplexing device may include, after the step of forming the plurality of holes, a step of forming a cladding layer on the one surface of the substrate, thereby reducing light loss.

[0035] (7) In the above (4), the wavelength multiplexing / demultiplexing device may have a plurality of second ports for outputting light, and the characteristics of the wavelength multiplexing / demultiplexing device may include a branching ratio of light to the plurality of second ports. Thus, the branching ratio can be set to a desired value.

[0036] (8) A wavelength combiner / demultiplexer, wherein the wavelength combiner / demultiplexer comprises a substrate, and a first port and a second port provided on the substrate, light is input to the first port and output from the second port, a plurality of holes are provided on one surface of the substrate, and three adjacent holes among the plurality of holes are arranged in a triangular lattice shape. Due to the thickness of the wall between adjacent holes, it is not easy to be damaged. Adjacent holes are not easy to couple with each other and are separated from each other. By providing the designed number and layout of holes, the desired characteristics can be obtained.

[0037] (9) In the above (8), the substrate may include a silicon layer, and the plurality of holes may be provided on one surface of the silicon layer. The plurality of holes are separated due to the wall thickness. The desired characteristics can be obtained.

[0038] (10) In the above (8) or (9), the three adjacent holes may be arranged in a triangular lattice. The plurality of holes are separated due to the wall thickness. The desired characteristics can be obtained.

[0039] (11) In any one of (8) to (10) above, the first port may include one port, and the second port may include a plurality of ports. The branching ratio can be set to a desired size.

[0040] (12) In any one of (8) to (11) above, the wavelength multiplexing / demultiplexing device may include a cladding layer provided on the one surface of the substrate, thereby reducing light loss.

[0041] (13) In any one of the above (8) to (12), the substrate may have a wall between adjacent holes, and the thickness of the wall may be 30 nm or more. Adjacent holes are not easily connected and are separated from each other. The desired characteristics can be obtained.

[0042] (14) In the above (9), the substrate may include the silicon layer and a buried oxide layer, and the buried oxide layer may be provided on a surface of the silicon layer opposite to the one surface. Thus, light loss is reduced.

[0043] (15) A demultiplexer, wherein the demultiplexer comprises a first multiplexer, a second multiplexer, and a third multiplexer, wherein the first multiplexer, the second multiplexer, and the third multiplexer respectively comprise a substrate and a first port and at least one second port provided on the substrate, wherein a plurality of holes are provided on one surface of the substrate, wherein three adjacent holes among the plurality of holes are arranged in a triangular lattice shape, wherein the at least one second port of the first multiplexer is two second ports, wherein one of the two second ports of the first multiplexer is coupled to the first port of the second multiplexer, and the other of the two second ports of the first multiplexer is coupled to the first port of the third multiplexer. The desired characteristics can be obtained.

[0044] (16) Based on the above (15), the substrate of each of the first multiplexer / demultiplexer, the second multiplexer / demultiplexer, and the third multiplexer / demultiplexer may have a silicon layer, and the plurality of holes are provided on one surface of the silicon layer. Due to the wall thickness, the plurality of holes are separated, and the desired characteristics can be obtained.

[0045] (17) Based on the above (15) or (16), in the first multiplexer / demultiplexer, the second multiplexer / demultiplexer, and the third multiplexer / demultiplexer, the three adjacent holes are configured in a regular triangle shape. Due to the wall thickness, the multiple holes are separated. The desired characteristics can be obtained.

[0046] (18) A design device for a wavelength combiner / demultiplexer, comprising a substrate, a first port for inputting light and a second port for outputting light disposed on the substrate, and a plurality of holes disposed on a surface of the substrate, wherein the design device comprises a control unit for designing the positions of the plurality of holes in such a manner that three adjacent holes among the plurality of holes are arranged in a triangular lattice. The walls between adjacent holes become thicker and are less susceptible to damage. Adjacent holes are less susceptible to coupling and are separated from each other. By setting the designed number and layout of holes, the desired characteristics can be obtained.

[0047] (19) In the above (18), the control unit may include a first design unit and a second design unit, wherein the first design unit performs a design for dividing the surface of the substrate into a plurality of regions arranged in a triangular lattice, and the second design unit performs a design for arranging the plurality of holes in a portion of the plurality of regions and not arranging holes in another portion of the plurality of regions. The wall becomes thicker and the plurality of holes are separated. The desired characteristics can be obtained.

[0048] (20) In the above (19), the planar shape of the region may be a regular hexagon, and the first design portion may arrange a plurality of the regions on the surface of the substrate in a closest-packed structure. The wall becomes thicker and the plurality of holes are separated. The desired characteristics can be obtained.

[0049] (21) In any one of (18) to (20) above, the control unit may design the positions of the plurality of holes based on the characteristics of the multiplexer / demultiplexer. A multiplexer / demultiplexer having a triangular lattice arrangement and desired characteristics can be manufactured.

[0050] (22) A computer-readable storage medium storing a design program for a wavelength combiner / demultiplexer having a substrate, a first port disposed on the substrate for inputting light, a second port for outputting light, and a plurality of holes disposed on a surface of the substrate, wherein the design program causes a computer to function as a design unit that designs the positions of the plurality of holes in the surface of the substrate so that three adjacent holes among the plurality of holes are arranged in a triangular lattice. The walls between adjacent holes become thicker and are less susceptible to damage. Adjacent holes are less susceptible to coupling and are separated from each other. By setting the number and layout of holes as designed, the desired characteristics can be obtained.

[0051] (23) Based on the above (22), the first design unit may divide the surface of the substrate into a plurality of regions arranged in a triangular lattice, or may arrange the plurality of holes in a portion of the plurality of regions and not arrange holes in another portion of the plurality of regions. The wall becomes thicker and the plurality of holes are separated. The desired characteristics can be obtained.

[0052] (24) In the above (23), the planar shape of the region may be a regular hexagon, and a plurality of the regions may be arranged on the surface of the substrate in a closest-packed structure. The wall becomes thicker and the plurality of holes are separated. The desired characteristics can be obtained.

[0053] (25) In any one of (22) to (24) above, the positions of the plurality of holes may be designed based on the characteristics of the wavelength combiner / demultiplexer. A wavelength combiner / demultiplexer having a triangular lattice arrangement and desired characteristics can be manufactured.

[0054] [Details of the embodiments of the present invention] Hereinafter, specific examples of the wavelength combiner / demultiplexer and its manufacturing method, design device, computer-readable storage medium and demultiplexer involved in the embodiments of the present invention are described with reference to the accompanying drawings. It should be noted that the present invention is not limited to these examples, but is represented by the scope of the claims, and is intended to include the meaning equivalent to the scope of the claims and all changes within the scope.

[0055] <First Embodiment> (Wavelength Combiner / Demultiplexer) Figure 1A 1 is a top view showing an example of a wavelength multiplexing / demultiplexing device 100 according to the first embodiment. The wavelength multiplexing / demultiplexing device is a mosaic-shaped passive optical element. The mosaic-shaped structure refers to a structure in which a plurality of holes 30 are arranged two-dimensionally in a plane as described later. The wavelength multiplexing / demultiplexing device 100 branches the incident light and emits it, or multiplexes a plurality of incident lights and emits them.

[0056] The wavelength multiplexer / demultiplexer 100 is formed on a substrate 10. The substrate 10 is, for example, a SOI (Silicon on Insulator) substrate. Two sides of the substrate 10 are parallel to the X-axis direction. The other two sides are parallel to the Y-axis direction. The upper surface of the substrate 10 is parallel to the XY plane. The Z-axis direction is the normal direction of the substrate 10. The X-axis direction, the Y-axis direction, and the Z-axis direction are orthogonal to each other. The H1 axis and the H2 axis are parallel to the XY plane and are inclined from the X-axis and the Y-axis. The inclination angle of the H1 axis from the X-axis is, for example, 30°. The inclination angle of the H2 axis from the X-axis is, for example, -30°.

[0057] The planar shape of the substrate 10 is a rectangle. The length L1 of the side in the X-axis direction of the substrate 10 is, for example, 2.4 μm. The length L2 of the side in the Y-axis direction is, for example, 2.4 μm.

[0058] The wavelength multiplexing / demultiplexing device 100 has a port 20, a port 22, and a port 24. These ports are silicon waveguides formed by a silicon layer 16 described later. The width of the port is, for example, 0.48 μm. The port 20 (first port) functions as, for example, an incident port. The port 22 and the port 24 (second port) function as, for example, an emission port. The port 20 is provided on one side of the substrate 10. The port 22 and the port 24 are provided on the other side of the substrate 10.

[0059] The wavelength multiplexing / demultiplexing device 100 has a plurality of holes 30. The plurality of holes 30 are two-dimensionally arranged in the plane of the substrate 10.

[0060] Figure 1B This is an enlarged top view of the hole 30. A plurality of holes 30 and a plurality of regions 32 (pixels) are arranged on the surface of the substrate 10. The regions 32 (pixels) are set in the design of the wavelength multiplexing / demultiplexing device 100, and the regions 32 may not actually be manufactured on the substrate 10. The hole 30 is manufactured on the substrate 10. Figure 1B The dotted line in is an imaginary line connecting the centers of the regions 32 .

[0061] The planar shape of the hole 30 is, for example, a circle. The planar shape of the region 32 is, for example, a regular hexagon. A portion of the plurality of regions 32 is provided with the hole 30, and another portion is not provided with the hole 30. The portion of the region 32 provided with the hole 30 is referred to as region 32a. The portion of the region 32 not provided with the hole 30 is referred to as region 32b. One hole 30 is located at the center of the region 32a. The center of the hole 30 coincides with the center of the region 32.

[0062] The plurality of holes 30 and the plurality of regions 32 are periodically arranged in the directions of the Y axis, the H1 axis, and the H2 axis. The plurality of regions 32 are arranged in a closest packing structure. One region 32 is surrounded by six regions 32. Two adjacent regions 32 share one edge and two vertices located at both ends of the edge.

[0063] The triangle 33 is a virtual equilateral triangle formed by connecting the centers of three mutually adjacent regions 32. The centers of the three regions 32a form the triangle 33. The triangle 33 is an equilateral triangle. That is, the adjacent holes 30 are arranged in a triangular lattice shape.

[0064] The length L3 between two opposite sides of the region 32 is, for example, 160 nm. The diameter D1 of the hole 30 is smaller than the length L3, and is, for example, 120 nm. The distance L4 between the centers of two adjacent holes 30 is, for example, 160 nm. The wall 34 is located between two adjacent holes 30. The wall 34 is thinnest on the line connecting the centers of two adjacent holes 30. The thickness T1 of the wall 34 at the thinnest part is, for example, 40 nm.

[0065] Figure 2A as well as Figure 2B 1 is a cross-sectional view showing an example of the wavelength multiplexing / demultiplexing device 100 . Figure 2A A cross section including the port 20 is shown. Figure 2B A cross section including the hole 30 is shown.

[0066] like Figure 2A as well as Figure 2B As shown, the substrate 10 includes a substrate 12, a buried oxide layer 14, and a silicon layer 16. The buried oxide layer 14 is stacked on one surface of the substrate 12. The silicon layer 16 is stacked on the surface of the buried oxide layer 14 opposite to the substrate 12. A cladding layer 18 is stacked on the surface of the silicon layer 16 opposite to the buried oxide layer 14. The substrate 12 and the silicon layer 16 are formed of silicon (Si). The buried oxide layer 14 and the cladding layer 18 are formed of an insulator such as silicon oxide (SiO2). The thickness of the buried oxide layer 14 is, for example, 3 μm. The thickness of the silicon layer 16 is, for example, 220 nm.

[0067] like Figure 2AAs shown, the silicon layer 16 has a waveguide core 15 and a platform 17. The waveguide core 15 functions as a port 20. The platform 17 is located on both sides of the waveguide core 15, and the waveguide core 15 is separated from the platform. In the platform 17, the silicon layer 16 forms a plane. A cladding layer 18 is buried between the waveguide core 15 and the platform 17. The port 22 and the port 24 have the same structure as the port 20.

[0068] exist Figure 2B In the figure, three holes 30 are provided in the silicon layer 16. The holes 30 penetrate the silicon layer 16 in the Z-axis direction, but they may not penetrate the silicon layer 16. The depth of the holes 30 can be controlled by etching time, etc. The inside of the holes 30 is filled with a cladding layer 18. The refractive index of the holes 30 is different from the refractive index of the silicon layer 16. Since the refractive index changes periodically within the plane of the substrate 10, the substrate 10 functions as a photonic crystal. Alternatively, the holes 30 are hollow and air is sealed inside. No holes 30 are provided in the region 32b in the silicon layer 16.

[0069] Figure 1A The arrows represent the input and output of light. The wavelength combiner / demultiplexer 100 functions as a demultiplexer with one input and two outputs. Light is input to the wavelength combiner / demultiplexer 100 from port 20. The light propagates within the plane of the substrate 10 and is emitted from ports 22 and 24. The branching ratio of light is determined by the layout of the holes 30. If the branching ratio is X:Y, X% of the light input from port 20 is output from port 22, and Y (=100-X)% is output from port 24. The configuration of the holes 30 is designed according to the desired branching ratio.

[0070] (Design device) Figure 3A 1 is a block diagram showing an example of a design device 110 for the wavelength multiplexing / demultiplexing device 100. The design device 110 designs the layout of the plurality of holes 30 in the wavelength multiplexing / demultiplexing device 100.

[0071] The design device 110 includes a control unit 50. The control unit 50 is a computer or the like, and functions as a first design unit 51 and a second design unit 52. The first design unit 51 performs a design for dividing the surface of the substrate 10 into a plurality of regions 32. The second design unit 52 designs the positions of the plurality of holes 30 by determining a region 32a and a region 32b from the plurality of regions 32.

[0072] Figure 3B is a block diagram showing the hardware structure of the control unit 50. Figure 3BAs shown, the control unit 50 includes a CPU (Central Processing Unit) 54, a RAM (Random Access Memory) 56, a ROM (Read Only Memory) 58, a storage device 60, and an interface 62. The CPU 54, the RAM 56, the ROM 58, the storage device 60, and the interface 62 are connected to each other via a bus or the like. The RAM 56 is a volatile memory that temporarily stores programs and data. The storage device 60 is a solid state drive (SSD) such as a flash memory, a hard disk drive (HDD) or the like. The storage device 60 stores programs and the like.

[0073] The control unit 50 realizes the first design unit 51 and the second design unit 52 by the CPU 54 executing the program stored in the RAM 56. Each unit of the control unit 50 may be hardware such as a circuit.

[0074] (Manufacturing method) Figure 3C as well as Figure 3D FIG. 1 is a flow chart showing an example of a method for manufacturing the wavelength multiplexing / demultiplexing device 100. Figure 3C As shown, the characteristics required for the wavelength multiplexing / demultiplexing device 100 are determined (step S10 ). The characteristics refer to the light branching ratio, etc. In addition, the size of the wavelength multiplexing / demultiplexing device 100 is also determined. The characteristics and the conditions such as the size of the components are input to the design device 110 .

[0075] Based on the characteristics determined in step S10, the wavelength multiplexing / demultiplexing device 100 is designed (step S12). The design is performed by performing inverse problem analysis using machine learning with the desired characteristics as input and the element structure as output. Specifically, the configuration of the plurality of holes 30 is set using Bayesian direct-binary-search (DBS).

[0076] Figure 3D 2 is a flowchart showing an example of the design process. The first design unit 51 divides the surface of the substrate 10 into a plurality of regions 32 (step S20). The regular hexagonal regions 32 are arranged in a closest-packed structure. The second design unit 52 determines the arrangement of the plurality of holes 30 (step S22).

[0077] like Figure 3CAs shown, the substrate 10 is exposed using an electron beam or the like to pattern the resist (step S14). The silicon layer 16 is dry-etched to form the waveguide core 15 and the plurality of holes 30 (step S16). After etching, the cladding layer 18 is formed (step S18). The wafer is cut to form the wavelength multiplexing / demultiplexing device 100.

[0078] Figure 4 1 is a top view showing an example of a method for manufacturing the wavelength multiplexing / demultiplexing device 100. Figure 4 As shown, in the design process ( Figure 3C In step S12), the arrangement of the holes 30 and the regions 32 is determined in the surface of the substrate 10. The planar shape of the region 32 is a regular hexagon. For example, on a 2.4 μm square substrate 10, 255 regions 32 are filled in a closest packing structure.

[0079] exist Figure 4 In FIG. 1 , the region 32 marked with 0 is a region 32a, in which a hole 30 is provided. The region 32 marked with 1 is a region 32b, in which no hole 30 is provided. Such a layout of the holes 30 is determined to realize the characteristics determined in step S10.

[0080] FIG. 5A to FIG. 5C FIG. 1 is a cross-sectional view showing an example of a method for manufacturing the wavelength multiplexing / demultiplexing device 100, and shows a cross section including the hole 30. FIG. 5A to FIG. 5C In, it means Figure 3C The process is a process from step S14 to step S18.

[0081] like Figure 5A As shown, a resist 40 is formed on the surface of the silicon layer 16 of the substrate 10 opposite to the buried oxide layer 14. The resist 40 is patterned by electron beam or the like. An opening 42 is formed in the resist 40 at a portion corresponding to the hole 30. Figure 5B As shown, for example, the portion of the silicon layer 16 exposed from the opening 42 is removed by inductively coupled plasma etching (ICP-RIE), thereby forming the hole 30. After etching, the etchant 40 is removed. Figure 5C As shown, the coating layer 18 is provided by, for example, a plasma CVD method (Plasma-Ehanced Chemical Vapor Deposition: plasma enhanced chemical vapor deposition, PECVD).

[0082] The port is also connected to FIG. 5A to FIG. 5C The same steps are used to form the cladding layer 18 by removing the portions on both sides of the waveguide core 15 in the silicon layer 16 by ICP-RIE.

[0083] Figure 6is a diagram showing an example of the branching ratio. The horizontal axis represents the wavelength of light. The vertical axis represents the branching ratio of light. Figure 6 An example with a branching ratio of 80:20 and an example with a branching ratio of 60:40 are recorded. In any example, the dotted line represents the design value. The solid line represents the measured value. The design value is set to the desired branching ratio, and the wavelength combiner 100 is designed and manufactured. The branching ratio in the manufactured wavelength combiner 100 is measured. The design value of the diameter of the hole 30 is 120nm, but there are also holes 30 with a diameter of 140nm due to the accuracy of etching, etc.

[0084] like Figure 6 As shown in Figure 1, in a wavelength band wider than the C band (1530nm to 1565nm), the measured value is close to the designed value. The excess loss is about 0.5dB. Figure 3C As shown, by setting the design values ​​to desired characteristics and designing the arrangement of the holes 30 , the desired characteristics can be realized.

[0085] (Comparative Example) Fig. 7A The figure shows an enlarged top view of the hole 30 in the wavelength combiner / demultiplexer involved in the comparative example. In the comparative example, the region 32 is a square. The plurality of regions 32 are arranged in a square grid shape, and the holes 30 are also arranged in a square grid shape. The square grid shape arrangement refers to a periodic arrangement in the X-axis direction and the Y-axis direction. As in the embodiment, the plurality of holes 30 are arranged two-dimensionally in a 2.4 μm square wavelength combiner / demultiplexer.

[0086] The length L5 of one side of the region 32 is, for example, 150 nm. The diameter D2 of the hole 30 is, for example, 120 nm. The thickness T2 of the wall 34 between two holes 30 is 30 nm, which is smaller than the thickness T1 of the wall 34 in the first embodiment.

[0087] In the comparative example, the wall 34 is thin. The wall disappears, and the two holes 30 are coupled into one, thereby deteriorating the characteristics. By increasing the area 32, the wall 34 can be thickened. However, if the size of the combiner is limited to 2.4μm×2.4μm, etc., it is difficult to set a predetermined number of holes 30, and there is a risk that the desired characteristics cannot be obtained. If the number of holes 30 is maintained and the wall 34 is thickened, the combiner becomes large. By reducing the hole 30, the wall 34 can be thickened. However, there is a risk that the characteristics will change due to the change in the size of the hole 30.

[0088] According to the first embodiment, Figure 4 As shown in FIG. 1 , the holes 30 are formed in the substrate 10 in such a manner that a plurality of adjacent holes 30 are arranged in a triangular lattice. Figure 1AAs shown in FIG. 1B , multiple holes 30 are arranged in a triangular lattice in the plane of the multiplexer / demultiplexer 100. The wall 34 between adjacent holes 30 becomes thicker. Since the wall 34 is thick and not easily damaged, the adjacent holes 30 are not easily coupled to each other and are separated from each other. Figure 6 As shown, by providing the designed number and layout of the holes 30, the desired characteristics can be obtained.

[0089] By configuring the region 32 in a triangular lattice shape, the wall 34 can be thickened without increasing the region 32. The number of holes 30 does not need to be reduced, and can be maintained at 255, for example. The desired number and layout of holes 30 can be provided in the wavelength multiplexing / demultiplexing device 100, for example, of 2.4 μm square. A wavelength multiplexing / demultiplexing device 100 that is small, such as several μm square, and has desired characteristics can be obtained.

[0090] like Figure 4 As shown, in the design process, the surface of the substrate 10 is divided into a plurality of regions 32. In the plurality of regions 32, regions 32a where holes 30 are provided and regions 32b where holes 30 are not provided are determined. By arranging the regions 32 two-dimensionally in a triangular lattice shape, the holes 30 are also arranged in a triangular lattice shape. By manufacturing the holes 30 based on the design, the wall 34 becomes thicker and the plurality of holes 30 are separated. The desired characteristics can be obtained.

[0091] like Figure 1B as well as Figure 4 As shown, the planar shape of the region 32 is set to a regular hexagon, and a plurality of regions 32 are arranged in a closest-packed structure. A plurality of holes 30 are arranged in a regular triangle lattice. The wall 34 is thickened, and the plurality of holes 30 are separated. The desired characteristics can be obtained.

[0092] like Figure 3C As shown, first, the characteristics are determined, and then the triangular lattice arrangement is designed based on the characteristics. It is possible to manufacture the multiplexing / demultiplexing device 100 having the triangular lattice arrangement and the desired characteristics.

[0093] For example, the hole 30 is formed in the silicon layer 16 of the substrate 10 by dry etching. There is a risk that the diameter D1 of the hole 30 is larger than the design value due to errors in the position of the resist pattern, side etching, etc. According to the first embodiment, since the wall 34 is thick, the tolerance is improved. Adjacent holes 30 are not easily connected and are easily separated from each other. Even in the case of errors, the desired characteristics can be obtained. The thickness T1 of the wall 34 is greater than 30nm, greater than 35nm, greater than 45nm, greater than 50nm, etc.

[0094] like Figure 1AAs shown, the substrate 10 is provided with a port 20, a port 22, and a port 24. Light is input from the port 20 and output from the port 22 and the port 24. The wavelength multiplexing / demultiplexing device 100 functions as a power distributor for branching light into two beams. By providing a plurality of holes 30, the branching ratio can be set to a desired size, and can be set as follows: Figure 6 The ratio of 80:20 as in the example of FIG. 1 can also be set to 60:40. The branch ratio can also be set to a desired size as in the example described later.

[0095] The number of output ports may be two or more, three or more, or four or more. The wavelength multiplexing / demultiplexing device 100 may multiplex light input from a plurality of ports. The wavelength multiplexing / demultiplexing device 100 may multiplex light input from two or more ports and output the multiplexed light.

[0096] The planar shape of the hole 30 may be a circle or a polygon, etc. The planar shape of the region 32 may be a polygon such as a hexagon, a quadrilateral, or a triangle, or may be a shape including a curve such as a circle.

[0097] The wavelength combiner / demultiplexer may be formed on the SOI substrate or may be formed on a component other than the SOI substrate. The waveguide may include a waveguide core 15 of Si or may be formed of other materials.

[0098] (Variation) Figure 7B This is an enlarged top view of the hole 30 in the wavelength multiplexing / demultiplexing device involved in the modified example. The area 32 is a square. Two adjacent areas 32 are arranged at a distance L6 from the square grid. If the distance L6 is set to 40nm, the thickness T3 of the wall 34 between the two holes 30 is 35nm, which becomes larger than the thickness T2 in the comparative example.

[0099] By shifting the holes 30 and the regions 32 from the square grid, a triangular grid arrangement can be achieved. If the distance L6 is set to half the length L5 of one side of the square grid, the arrangement can be as follows: Figure 1B The equilateral triangle grid arrangement shown.

[0100] <Second Embodiment> Figure 8 FIG. 1 is a top view of a wavelength multiplexing / demultiplexing device 200 according to the second embodiment. The same structure as the first embodiment is omitted. In the second embodiment, the light intensity branching ratio is set to 90:10. The branching ratio of 90:10 is the desired characteristic. Figure 3C The arrangement of the holes 30 is determined according to the branching ratio, so as to form a Figure 8 The hole 30 is shown.

[0101] The wavelength multiplexing / demultiplexing device 200 splits the light input from the port 20 into two beams and outputs the two beams. The ratio of the intensity of the light output from the port 22 to the intensity of the light output from the port 24 is 90:10.

[0102] <Third Embodiment> Fig. 9 1 is a top view of a wavelength multiplexing / demultiplexing device 300 according to the third embodiment. The description of the same structure as the first embodiment or the second embodiment is omitted. In the third embodiment, the branching ratio of light is set to 70:30. The ratio of the intensity of the light output from the port 22 to the intensity of the light output from the port 24 is 70:30.

[0103] <Fourth Embodiment> Fig.10 1 is a top view of a wavelength multiplexing / demultiplexing device 400 according to the fourth embodiment. The description of the same structure as the first to third embodiments is omitted. In the fourth embodiment, the branching ratio of light is set to 50:50. The ratio of the intensity of the light output from the port 22 to the intensity of the light output from the port 24 is 50:50.

[0104] like Figure 8 as well as Fig. 9 As shown, more holes 30 are provided between port 20 and port 24 than between port 20 and port 22. In other words, more holes 30 are provided near port 24, which has a lower output, than port 22, which has a higher output, of the two ports. Fig.10 As shown, in the example where the branching ratio is 50:50, the arrangement of the holes 30 is symmetrical about the X axis.

[0105] Fig.11 : is a diagram showing branching ratios by example. The dashed line represents an example of 90:10 (second embodiment). The solid line represents an example of 70:30 (third embodiment). The dotted line represents an example of 50:50 (fourth embodiment). In each example, the branching ratio is near the design value. By setting the configuration of the holes 30 based on the desired branching ratio, a wavelength combiner / demultiplexer corresponding to the branching ratio can be manufactured. The excess loss is about 0.5 dB. Since damage to the wall 34 is suppressed, multiple holes 30 are separated, thereby reducing light loss.

[0106] <Fifth Embodiment> Fig.12 1 is a plan view showing an example of a demultiplexer 500 according to the fifth embodiment. The description of the same structures as those of the first to fourth embodiments will be omitted.

[0107] The demultiplexer 500 includes three wavelength multiplexing / demultiplexing devices: a wavelength multiplexing / demultiplexing device 510, a wavelength multiplexing / demultiplexing device 520, and a wavelength multiplexing / demultiplexing device 530. For example, the length L7 of a wavelength multiplexing / demultiplexing device in the X-axis direction is 17.2 μm. The length L8 in the Y-axis direction is 7.5 μm. The wavelength multiplexing / demultiplexing device 510 (the first wavelength multiplexing / demultiplexing device) includes a port 20a, a port 22a, and a port 24a. The wavelength multiplexing / demultiplexing device 520 (the second wavelength multiplexing / demultiplexing device) includes a port 20b, a port 22b, and a port 24b. The wavelength multiplexing / demultiplexing device 530 (the third wavelength multiplexing / demultiplexing device) includes a port 20c, a port 22c, and a port 24c.

[0108] Port 22a of the wavelength multiplexer / demultiplexer 510 is optically coupled to port 20b of the wavelength multiplexer / demultiplexer 520. Port 24a of the wavelength multiplexer / demultiplexer 510 is optically coupled to port 20c of the wavelength multiplexer / demultiplexer 530. The ports may be coupled, for example, via a silicon waveguide or a transmission line such as an optical fiber.

[0109] The three wavelength combiners and demultiplexers have a plurality of holes 30. The diameter of the hole 30 is 160 nm. The center-to-center distance between two holes 30 is 250 nm. In each wavelength combiner and demultiplexer, the plurality of holes 30 are arranged in a triangular lattice. The layout of the holes 30 is determined according to the characteristics required by the wavelength combiner and demultiplexer. The three wavelength combiners and demultiplexers branch each wavelength of light into two beams. The demultiplexer 500 is a device with one input and four outputs, which branches each wavelength of light into four beams.

[0110] The wavelength multiplexing / demultiplexing device 510 splits the light input from the port 20a into two beams according to the wavelength and outputs them. The light with a wavelength of 1590nm and the light with a wavelength of 1570nm are output from the port 22a and input from the port 20b to the wavelength multiplexing / demultiplexing device 520. The light with a wavelength of 1550nm and the light with a wavelength of 1530nm are output from the port 24a and input from the port 20c to the wavelength multiplexing / demultiplexing device 530.

[0111] The wavelength multiplexing / demultiplexing device 520 emits light with a wavelength of 1590 nm from the port 22b and emits light with a wavelength of 1570 nm from the port 24b. The wavelength multiplexing / demultiplexing device 530 emits light with a wavelength of 1550 nm from the port 22c and emits light with a wavelength of 1530 nm from the port 24c.

[0112] Fig.13 2 is a graph showing transmittance by example. The horizontal axis represents the wavelength of light. The vertical axis represents transmittance. The ratio of the intensity of light output from each port to the intensity of light input to the port 20a of the demultiplexer 500 is measured. Fig.13 The dashed line in FIG. 1 represents the transmittance of port 24c. The dashed line represents the transmittance of port 22c. The dotted line represents the transmittance of port 24b. The solid line represents the transmittance of port 22b.

[0113] The transmittance of port 24c has a peak near 1525nm. The transmittance of port 22c has a peak near 1545nm. The transmittance of port 24b has a peak near 1565nm. The transmittance of port 22b has a peak near 1585nm. The insertion loss of the demultiplexer 500 as a whole is about 7dB. The extinction ratio is above 3dB.

[0114] According to the fifth embodiment, the port 22a of the wavelength multiplexing / demultiplexing device 510 is coupled to the port 20b of the wavelength multiplexing / demultiplexing device 520. The port 24a of the wavelength multiplexing / demultiplexing device 510 is coupled to the port 20c of the wavelength multiplexing / demultiplexing device 530. The wavelength multiplexing / demultiplexing device 520 branches the light input to the port 20b into two beams, and outputs them from the port 22b and the port 24b. The wavelength multiplexing / demultiplexing device 530 branches the light input to the port 20c into two beams, and outputs them from the port 22c and the port 24c. The demultiplexer 500 branches the light into four beams according to the wavelength. In the three wavelength multiplexing / demultiplexing devices, the plurality of holes 30 are arranged in a triangular lattice shape. The wall 34 becomes thicker, and adjacent holes 30 are not easily connected. The deterioration of the characteristics of each wavelength multiplexing / demultiplexing device can be suppressed, and the desired characteristics can be obtained in the demultiplexer 500.

[0115] It is also possible to connect more than three wavelength multiplexing / demultiplexing devices to form a demultiplexer. For example, four wavelength multiplexing / demultiplexing devices are coupled to the output port of a wavelength multiplexing / demultiplexing device with one input and four outputs. The four wavelength multiplexing / demultiplexing devices each branch the light into two beams. The demultiplexer branches the light into eight beams according to the wavelength.

[0116] The above-mentioned functions of the design can be realized by a computer. In this case, a program describing the processing content of the functions that the processing device should have is provided. By executing the program using a computer, the above-mentioned processing functions are realized on the computer. The program describing the processing content can be stored in a computer-readable storage medium (which does not include a carrier wave).

[0117] When distributing the program, for example, it is sold in the form of a portable storage medium such as a DVD (Digital Versatile Disc) or a CD-ROM (Compact Disc Read Only Memory) storing the program. Alternatively, the program may be stored in a storage device of a server computer and transferred from the server computer to other computers via a network.

[0118] The computer executing the program, for example, stores the program stored in a mobile storage medium or the program transmitted from a server computer in its own storage device. Then, the computer reads the program from its own storage device and executes the processing according to the program. It should be noted that the computer can also directly read the program from the mobile storage medium and execute the processing according to the program. In addition, it can also be that each time a program is transmitted from a server computer, the computer sequentially executes the processing according to the received program.

[0119] As mentioned above, although embodiment of this invention is described in detail, this invention is not limited to the said specific embodiment, Various deformation|transformation and change are possible within the range of the summary of this invention described in a claim.

Claims

1. A method for manufacturing a wavelength multiplexer / demultiplexer, comprising a substrate, a first port for inputting light, and a second port for outputting light, which is provided on the substrate, wherein: The manufacturing method of the wavelength combiner / demultiplexer comprises the following steps: Designing positions of the plurality of holes in such a manner that three adjacent holes among the plurality of holes are arranged in a triangular lattice; and The plurality of holes are formed on one surface of the substrate.

2. The method for manufacturing a wavelength combiner / demultiplexer according to claim 1, wherein: The step of designing the positions of the plurality of holes includes the steps of: dividing the surface of the substrate into a plurality of regions arranged in a triangular lattice; And the holes are arranged in a part of the plurality of regions, and the holes are not arranged in another part of the plurality of regions.

3. The method for manufacturing a wavelength combiner / demultiplexer according to claim 2, wherein: The plane shape of the region is a regular hexagon, The step of dividing the surface of the substrate into the plurality of regions includes the step of arranging the plurality of regions in a closest-packed structure.

4. The method for manufacturing a wavelength combiner / demultiplexer according to claim 1, wherein: The step of designing the positions of the plurality of holes is a step of designing the positions of the plurality of holes based on the characteristics of the wavelength multiplexing / demultiplexing device.

5. The method for manufacturing a wavelength combiner / demultiplexer according to claim 1, wherein: The step of forming the plurality of holes includes forming the holes by dry etching the silicon layer of the substrate.

6. The method for manufacturing a wavelength combiner / demultiplexer according to claim 1, wherein: The method for manufacturing a wavelength multiplexing / demultiplexing device includes, after the step of forming the plurality of holes, a step of forming a cladding layer on the one surface of the substrate.

7. The method for manufacturing a wavelength combiner / demultiplexer according to claim 4, wherein: The wavelength multiplexing / demultiplexing device has a plurality of second ports for outputting light. The characteristics of the wavelength multiplexing / demultiplexing device include a branching ratio of light to the plurality of second ports.

8. A wavelength combiner / demultiplexer, wherein: The wavelength combiner / demultiplexer has: substrate; and The first port and the second port are arranged on the substrate, Light is input into the first port and output from the second port, A plurality of holes are provided on one surface of the substrate, Three adjacent holes among the plurality of holes are arranged in a triangular lattice.

9. The wavelength combiner / demultiplexer according to claim 8, wherein: The substrate has a silicon layer, The plurality of holes are provided on one surface of the silicon layer.

10. The wavelength combiner / demultiplexer according to claim 8, wherein: The three adjacent holes are arranged in a regular triangle shape.

11. The wavelength combiner / demultiplexer according to claim 8, wherein: The first port has one port, and the second port has a plurality of ports.

12. The wavelength multiplexing / demultiplexing device according to claim 8, wherein: The wavelength multiplexing / demultiplexing device includes a cladding layer provided on the one surface of the substrate.

13. The wavelength combiner / demultiplexer according to claim 8, wherein: The substrate has walls between adjacent holes. The wall has a thickness of 30 nm or more.

14. The wavelength combiner / demultiplexer according to claim 9, wherein: The substrate has the silicon layer and the buried oxide layer, The buried oxide layer is disposed on a surface of the silicon layer opposite to the one surface.

15. A demultiplexer, wherein: The demultiplexer has: The first wave combiner and splitter; A second wavelength multiplexer / demultiplexer; and The third multiplexer / demultiplexer, The first wavelength multiplexing / demultiplexing device, the second wavelength multiplexing / demultiplexing device, and the third wavelength multiplexing / demultiplexing device respectively include: substrate; as well as A first port and at least one second port are provided on the substrate, A plurality of holes are provided on one surface of the substrate, Three adjacent holes among the plurality of holes are arranged in a triangular lattice shape, The at least one second port of the first wavelength combiner / demultiplexer is two second ports, One of the two second ports of the first wavelength multiplexing / demultiplexing device is coupled to the first port of the second wavelength multiplexing / demultiplexing device, The other of the two second ports of the first wavelength multiplexer / demultiplexer is coupled to the first port of the third wavelength multiplexer / demultiplexer.

16. The demultiplexer according to claim 15, wherein: The substrate of each of the first wavelength multiplexing / demultiplexing device, the second wavelength multiplexing / demultiplexing device, and the third wavelength multiplexing / demultiplexing device has a silicon layer, The plurality of holes are provided on one surface of the silicon layer.

17. The demultiplexer according to claim 15, wherein: In the first wavelength multiplexing / demultiplexing device, the second wavelength multiplexing / demultiplexing device, and the third wavelength multiplexing / demultiplexing device, the three adjacent holes are arranged in a regular triangle shape.

18. A design device for a wavelength combiner / demultiplexer, comprising a substrate, a first port for inputting light and a second port for outputting light provided on the substrate, and a plurality of holes provided on a surface of the substrate, wherein: The wavelength multiplexing / demultiplexing device designing device includes a control unit that designs the positions of the plurality of holes so that three adjacent holes among the plurality of holes are arranged in a triangular lattice in the surface of the substrate.

19. The design device for a wavelength combiner / demultiplexer according to claim 18, wherein: The control unit includes a first design unit and a second design unit. The first design unit performs design for dividing the surface of the substrate into a plurality of regions arranged in a triangular lattice. The second designing unit performs designing such that the plurality of holes are arranged in a part of the plurality of regions, respectively, and no holes are arranged in another part of the plurality of regions.

20. The design device for a wavelength combiner / demultiplexer according to claim 19, wherein: The plane shape of the region is a regular hexagon, The first design section arranges the plurality of regions on the surface of the substrate in a closest-packed structure.

21. The design device for a wavelength combiner / demultiplexer according to claim 18, wherein: The control unit designs the positions of the plurality of holes based on the characteristics of the wavelength multiplexing / demultiplexing device.

22. A computer-readable storage medium storing a design program for a wavelength combiner / demultiplexer having a substrate, a first port disposed on the substrate for inputting light, a second port disposed on the substrate for outputting light, and a plurality of holes disposed on a surface of the substrate, wherein: The design program causes a computer to function as a design unit that designs the positions of the plurality of holes so that three adjacent holes among the plurality of holes are arranged in a triangular lattice in the surface of the substrate.

23. The computer-readable storage medium of claim 22, wherein: The design unit performs design for dividing the surface of the substrate into a plurality of regions arranged in a triangular lattice. The designing unit performs designing so that the plurality of holes are arranged in a part of the plurality of regions, respectively, and no holes are arranged in another part of the plurality of regions.

24. The computer-readable storage medium of claim 23, wherein: The plane shape of the region is a regular hexagon, The plurality of regions are arranged on the surface of the substrate in a closest-packed structure.

25. The computer-readable storage medium of claim 22, wherein: Designing the positions of the plurality of holes is performed based on the characteristics of the wavelength multiplexing / demultiplexing device.

Images