Optical waveguide device

Abstract

To provide an optical waveguide device allowing an optical waveguide to be inspected before a silicon photonics chip is mounted.SOLUTION: The optical waveguide device comprises: a first cladding layer; a plurality of core layers formed on the first cladding layer; and a second cladding layer formed on the first cladding layer and selectively covering the core layer. A first region not covered by the second cladding layer is provided on the first cladding layer. The plurality of core layer includes a plurality of signal core layers having one end arranged on the first region and inputting and outputting signal light, and an inspection core layer having one end and the other end exposed to an outer peripheral surface and inputting and outputting inspection light. The inspection core layer is formed of the same material as the signal core layer and has a cross-sectional shape in a short direction same as a cross-sectional shape of the signal core layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical waveguide device. [Background technology]

[0002] An optical waveguide device having an optical waveguide including a core layer and a clad layer is known. Such an optical waveguide device is equipped with a silicon photonics chip and is optically coupled to the optical waveguide, and is used in data centers and the like where various computers, data communication devices, and the like are installed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 2011-237504 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned optical waveguide device, it may be difficult to perform non-destructive inspection of the optical waveguide when the silicon photonics chip is not mounted. However, if the optical waveguide can be inspected only after the silicon photonics chip is mounted, defects in the optical waveguide cannot be found in advance. As a result, the optical waveguide device mounted with the silicon photonics chip becomes a defective product, leading to a decrease in yield.

[0005] The present invention has been made in consideration of the above-mentioned points, and has an object to provide an optical waveguide device that allows inspection of an optical waveguide before a silicon photonics chip is mounted. [Means for solving the problem]

[0006] This optical waveguide device has a first clad layer, a plurality of core layers formed on the first clad layer, and a second clad layer formed on the first clad layer and selectively covering the core layers, wherein a first region not covered by the second clad layer is provided on the first clad layer, and the plurality of core layers include a plurality of signal core layers having one end disposed in the first region and inputting and outputting signal light, and an inspection core layer having one end and the other end exposed to the outer circumferential surface and inputting and outputting inspection light, wherein the inspection core layer is formed from the same material as the signal core layer, and the cross-sectional shape in the short side direction of the inspection core layer is the same as the cross-sectional shape in the short side direction of the signal core layer. Effect of the Invention

[0007] According to the disclosed technique, it is possible to provide an optical waveguide device that allows inspection of an optical waveguide before mounting a silicon photonics chip. [Brief description of the drawings]

[0008] [Figure 1] 1A and 1B are diagrams illustrating an optical waveguide device according to a first embodiment. [Diagram 2] 1A to 1C are schematic diagrams illustrating a method for inspecting a core layer for inspection. [Diagram 3] 1 is a plan view illustrating an optical waveguide device according to a first modified example of the first embodiment. FIG. [Figure 4] 11 is a plan view illustrating an optical waveguide device according to a second modified example of the first embodiment. FIG. [Diagram 5] 11 is a plan view illustrating an optical waveguide device according to a third modified example of the first embodiment. FIG. [Figure 6] FIG. 11 is a plan view illustrating an optical waveguide device according to a fourth modified example of the first embodiment. [Figure 7] 13 is a plan view illustrating an optical waveguide device according to a fifth modified example of the first embodiment. FIG. [Figure 8] 13 is a partial cross-sectional view illustrating an optical waveguide device according to a sixth modified example of the first embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and duplicated explanations may be omitted.

[0010] First embodiment [Optical waveguide device] 1A and 1B are diagrams illustrating an optical waveguide device according to a first embodiment, where FIG. 1A is a plan view, FIG. 1B is a cross-sectional view along line AA in FIG. 1A, and FIG. 1C is a cross-sectional view along line BB in FIG. 1A.

[0011] With reference to FIG. 1, the optical waveguide device 1 has a first cladding layer 21, signal core layers 22a to 22d, an inspection core layer 22t, and a second cladding layer .

[0012] The first cladding layer 21 is located at the bottom. The thickness of the first cladding layer 21 may be, for example, about 10 μm to 30 μm. The refractive index of the first cladding layer 21 may be, for example, about 1.5. The first cladding layer 21 may be formed from a photosensitive resin such as a polyimide resin, an acrylic resin, an epoxy resin, a polyolefin resin, or a polynorbornene resin.

[0013] The signal core layers 22a to 22d are formed on the first cladding layer 21. In the illustrated example, each of the signal core layers 22a to 22d includes four signal core layers arranged side by side at a predetermined interval. Each of the signal core layers 22a to 22d may include any number of signal core layers, which may be one or more. The optical waveguide device 1 may include a plurality of signal core layers. For example, the optical waveguide device 1 may include the signal core layer 22a including one signal core layer and the signal core layer 22b including one signal core layer, and may not include the signal core layers 22c and 22d.

[0014] The signal core layers 22a to 22d are core layers through which signal light is input and output. In the signal core layers 22a to 22d, the cross-sectional shape in the short side direction of each of the signal core layers is, for example, rectangular. In the signal core layers 22a to 22d, the width of each of the signal core layers can be, for example, about 5 μm to 10 μm. In the signal core layers 22a to 22d, the thickness of each of the signal core layers can be, for example, about 5 μm to 10 μm. In the signal core layers 22a to 22d, the refractive index of each of the signal core layers is higher than the refractive index of the first cladding layer 21 and the second cladding layer 23, and can be, for example, about 1.6. The signal core layers 22a to 22d can be formed of, for example, a material appropriately selected from the materials exemplified as the material of the first cladding layer 21.

[0015] The inspection core layer 22t is formed on the first clad layer 21. In the illustrated example, the inspection core layer 22t includes three inspection core layers arranged side by side at a predetermined interval. The inspection core layer 22t may include any number of inspection core layers, which may be one or more.

[0016] The inspection core layer 22t is a core layer for inputting and outputting inspection light. In the inspection core layer 22t, the cross-sectional shape in the short-side direction of each of the inspection core layers is, for example, rectangular. The inspection core layer 22t is formed with the same specifications as the signal core layers 22a to 22d. That is, the inspection core layer 22t is formed of the same material as the signal core layers 22a to 22d. Furthermore, the cross-sectional shape in the short-side direction of each of the inspection core layers in the inspection core layer 22t is the same as the cross-sectional shape in the short-side direction of each of the signal core layers in the signal core layers 22a to 22d. In other words, the width of each of the inspection core layers in the inspection core layer 22t is the same as the width of each of the signal core layers in the signal core layers 22a to 22d. Furthermore, the thickness of each of the inspection core layers in the inspection core layer 22t is the same as the thickness of each of the signal core layers in the signal core layers 22a to 22d.

[0017] The inspection core layer 22t and the signal core layers 22a to 22d are simultaneously formed by photolithography using a film-like material. Therefore, even if there is an error in the width of both due to the manufacturing variation in the photolithography method, it is within the same range. Also, even if there is an error in the thickness of both due to the inherent error of the film-like material, it is within the same range.

[0018] The second cladding layer 23 is formed on the first cladding layer 21, and selectively covers the signal core layers 22a to 22d and the inspection core layer 22t. If necessary, a part of the inspection core layer 22t may be exposed from the second cladding layer 23. The thickness of the second cladding layer 23 may be, for example, about 10 μm to 30 μm. The refractive index of the second cladding layer 23 may be, for example, about 1.5. The second cladding layer 23 is a cured photosensitive resin. The second cladding layer 23 may be formed, for example, from a material appropriately selected from the materials exemplified for the first cladding layer 21.

[0019] In the optical waveguide device 1, a single mode signal optical waveguide 20 is configured by the first cladding layer 21, the signal core layers 22a to 22d, and the second cladding layer 23. In the signal core layers 22a to 22d, each of the signal core layers does not have to be formed in a straight line and may include a curved portion. In the signal core layers 22a to 22d, the interval between adjacent signal core layers may or may not be constant.

[0020] In the optical waveguide device 1, the first cladding layer 21, the inspection core layer 22t, and the second cladding layer 23 constitute a single-mode inspection optical waveguide 20T. In the inspection core layers 22t, each inspection core layer does not have to be formed in a straight line, and may include a curved portion. In the inspection core layers 22t, the interval between adjacent inspection core layers may be constant or may not be constant.

[0021] The optical waveguide device 1 has a first region E, which is not covered by the second cladding layer 23, provided on the first cladding layer 21. The first region E is a region where a silicon photonics chip can be mounted. One ends of the signal core layers 22a to 22d are disposed in the first region E. That is, one ends of the signal core layers 22a to 22d are exposed from the second cladding layer 23 in a plan view.

[0022] In the illustrated example, one end of the signal core layer 22a faces one end of the signal core layer 22b with a gap therebetween. Also, one end of the signal core layer 22c faces one end of the signal core layer 22d with a gap therebetween. The other ends of the signal core layers 22a to 22d are exposed to the outer circumferential surface (side surface) of the optical waveguide device 1. Meanwhile, one and the other ends of the inspection core layer 22t are exposed to the outer circumferential surface of the optical waveguide device 1.

[0023] Since one ends of the signal core layers 22a to 22d are not exposed on the outer peripheral surface of the optical waveguide device 1, it is difficult to input and output light without a silicon photonics chip mounted thereon. That is, it is difficult to non-destructively inspect the signal optical waveguide 20 without a silicon photonics chip mounted thereon.

[0024] Therefore, in the optical waveguide device 1, an inspection optical waveguide 20T is provided in addition to the signal optical waveguide 20. Since one end and the other end of the inspection core layer 22t are exposed to the outer circumferential surface of the optical waveguide device 1, the inspection optical waveguide 20T can easily input and output light. That is, the inspection optical waveguide 20T can be inspected before mounting the silicon photonics chip. By inspecting the inspection optical waveguide 20T, the quality of the inspection core layer 22t can be judged. As a result, the quality of the signal core layers 22a to 22d formed to the same specifications as the inspection core layer 22t can be estimated with high accuracy.

[0025] Fig. 2 is a schematic diagram for explaining a method for inspecting a core layer for inspection. In Fig. 2, light emitted from a light emitting unit 110 is incident on one end of the core layer for inspection 22t, and light emitted from the other end of the core layer for inspection 22t is received by a light receiving unit 120. The light received by the light receiving unit 120 is converted into an electrical signal and analyzed, thereby making it possible to inspect the core layer for inspection 22t. The light emitting unit 110 is, for example, an optical fiber. The light receiving unit 120 is, for example, a camera capable of detecting a near field pattern (NFP).

[0026] Specifically, for example, it is inspected whether the light guided through the inspection core layer 22t is in a single mode. Whether the light is in a single mode or not is determined by the formation accuracy of the inspection core layer 22t, that is, whether the width and thickness of the inspection core layer 22t are within the range of the allowable error. Therefore, if the inspection result is in a single mode, it can be confirmed that there is no problem with the formation accuracy of the inspection core layer 22t. As a result, it can be estimated with high accuracy that there is no problem with the formation accuracy of the signal core layers 22a to 22d formed to the same specifications as the inspection core layer 22t. As a result, it is possible to improve the yield of the optical waveguide device 1 after the silicon photonics chip is mounted.

[0027] In order to improve the degree of freedom in designing the signal core layers 22a to 22d, the inspection core layer 22t is preferably disposed near the outer periphery of the first cladding layer 21 in a plan view, and more preferably disposed at a corner. In the optical waveguide device 1, the inspection core layer 22t is disposed at the lower right corner of the first cladding layer 21 in a plan view.

[0028] That is, in the optical waveguide device 1, the first cladding layer 21 has four sides in a plan view, and the side on which one end of the inspection core layer 22t is located is different from the side on which the other ends of the signal core layers 22a to 22d are located in a plan view. Also, the side on which the other end of the inspection core layer 22t is located is the same as the side on which the other ends of the signal core layers 22b and 22d are located in a plan view.

[0029] In addition, in the optical waveguide device 1, the inspection core layer 22t includes a portion that is not parallel to the signal core layers 22a to 22d in a plan view. Specifically, in the optical waveguide device 1, the inspection core layer 22t is linear in a plan view, and is disposed at an inclination angle of about 45 degrees with respect to the linear signal core layers 22a to 22d. This configuration makes it easier to dispose the inspection core layer 22t at a corner of the second cladding layer 23 in a plan view. Note that the inspection core layer 22t may be disposed at an inclination angle other than 45 degrees with respect to the linear signal core layers 22a to 22d.

[0030] Modification of the First Embodiment In the modified example of the first embodiment, examples are shown in which the shape of the testing core layer is different, and examples in which a silicon photonics chip is mounted, etc. Note that in the modified example of the first embodiment, the description of the same components as those in the embodiment already described may be omitted.

[0031] 3 is a plan view illustrating an optical waveguide device according to Modification 1 of the first embodiment. An optical waveguide device 1A shown in FIG.

[0032] In the optical waveguide device 1A, the first cladding layer 21 has four or more sides in a plan view. In addition, in a plan view, a side on which one end of the inspection core layer 22t is located is different from a side on which the other ends of the signal core layers 22a to 22d are located. In addition, in a plan view, a side on which the other end of the inspection core layer 22t is located is different from a side on which the other ends of the signal core layers 22a to 22d are located.

[0033] In the optical waveguide device 1A, the inspection core layer 22t is formed in the protrusion 10. The protrusion 10 can be formed, for example, by providing a cutout having a right-angled isosceles triangle shape in plan view from two sides forming the lower right corner of the optical waveguide device 1 having the shape shown in FIG.

[0034] The protrusion 10 has a first side 11 and a second side 12 parallel to the first side 11 in a plan view. In addition, in a plan view, one end of the inspection core layer 22t is located on the first side 11, and the other end is located on the second side 12. In a plan view, the longitudinal direction of the inspection core layer 22t is perpendicular to the first side 11 and the second side 12. Note that the parallel and perpendicular directions here allow an error of ±5 degrees.

[0035] With this configuration, one end and the other end of the inspection core layer 22t are perpendicular to the first side 11 and the second side 12. This allows one end of the inspection core layer 22t to be closer to the light-emitting section 110 and the other end to be closer to the light-receiving section 120 than in the case where one end and the other end of the inspection core layer 22t are inclined with respect to the side of the first cladding layer 21 as in the optical waveguide device 1. As a result, the inspection of the inspection core layer 22t can be performed easily and with high accuracy.

[0036] FIG. 4 is a plan view illustrating an optical waveguide device according to a second modified example of the first embodiment. The optical waveguide device 1B shown in FIG. 4 differs from the optical waveguide device 1 in that the inspection core layer 22t is curved. FIG. 5 is a plan view illustrating an optical waveguide device according to a third modified example of the first embodiment. The optical waveguide device 1C shown in FIG. 5 differs from the optical waveguide device 1 in that the inspection core layer 22t includes a curved portion and a straight portion. In the optical waveguide device 1C, the inspection core layer 22t is disposed near the outer periphery, not at the corner of the first cladding layer 21, in a plan view. In this way, the shape of the inspection core layer 22t is not limited to a straight line, and can be any shape.

[0037] Fig. 6 is a plan view illustrating an optical waveguide device according to a fourth modified example of the first embodiment. The optical waveguide device 1D shown in Fig. 6 differs from the optical waveguide device 1 in that the inspection core layer 22t is parallel to the signal core layers 22a to 22d. In the optical waveguide device 1D, the inspection core layer 22t is disposed near the outer periphery, not at the corner of the first cladding layer 21, in a plan view. In this way, the inspection core layer 22t is not limited to a form including a portion not parallel to the signal core layers 22a to 22d as in the optical waveguide devices 1, 1A, 1B, and 1C, and may be parallel to the signal core layers 22a to 22d.

[0038] Fig. 7 is a plan view illustrating an optical waveguide device according to Modification 5 of the first embodiment. The optical waveguide device 1E shown in Fig. 7 differs from the optical waveguide device 1 in that it has a silicon photonics chip 30. The optical waveguide device 1E has connectors 40 connected to the signal core layers 22a to 22d at both ends of the signal optical waveguide 20, but may not have the connectors 40.

[0039] The silicon photonics chip 30 includes, for example, a silicon substrate and a silicon waveguide provided on one surface of the silicon substrate. The silicon waveguide is a fine optical waveguide built into the silicon chip, and is used in silicon photonics technology for integrating optical circuits and the like on the silicon chip.

[0040] The silicon substrate has a thickness of, for example, about 100 μm to 800 μm. The silicon waveguide can be provided on, for example, a protective film provided on the silicon substrate. The protective film can be, for example, SiO 2 Or SiO X The protective film may be formed from, for example, about 2 μm to 6 μm. The silicon waveguide may be embedded in the silicon substrate.

[0041] The silicon photonics chip 30 is disposed in the first region E with the silicon waveguide facing one end side of the signal core layers 22a-22d, and the silicon waveguide is optically coupled to one end of the signal core layers 22a-22d. The silicon waveguide is, for example, adiabatically coupled to one end of the signal core layers 22a-22d. When the silicon waveguide protrudes from the silicon substrate to one end side of the signal core layers 22a-22d, a part or the whole of the silicon waveguide may be embedded in the signal core layers 22a-22d. In the silicon waveguide, the part optically coupled to one end of the signal core layers 22a-22d may be tapered.

[0042] Fig. 8 is a partial cross-sectional view illustrating an optical waveguide device according to Modification 6 of Embodiment 1. An optical waveguide device 1F shown in Fig. 8 differs from optical waveguide device 1E in that it has a wiring board.

[0043] In the optical waveguide device 1F, the first cladding layer 21, the signal core layers 22a to 22d, the inspection core layer 22t, the second cladding layer 23, and the silicon photonics chip 30 are mounted on a wiring substrate 50. The optical waveguide device 1F may or may not include a connector 40.

[0044] The wiring board 50 is formed of an insulating resin material such as an epoxy resin or a polyimide resin. The wiring board 50 may have a reinforcing member such as a glass cloth. The wiring board 50 may have a laminated structure of one or more insulating layers and one or more wiring layers. The wiring board 50 may be a rigid board having high rigidity, or a flexible board having low rigidity. The wiring board 50 is, for example, a build-up board, a silicon board, a ceramic board, or the like.

[0045] A semiconductor chip may be mounted on the wiring board 50. The mounted semiconductor chip may be, for example, an ASIC or a logic IC. Also, a PHY chip may be mounted. The PHY chip is a chip that forms a physical interface and can, for example, encode and decode data.

[0046] In this way, the optical waveguide device may be mounted on a wiring board. In this manner, various functions can be realized. Note that even an optical waveguide device that does not have a silicon photonics chip, such as the optical waveguide device 1, may be mounted on a wiring board.

[0047] Although the preferred embodiments have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims. [Explanation of symbols]

[0048] 1,1A,1B,1C,1D,1E,1F Optical waveguide device 10 Protrusion 11 Side 1 12 Side 2 20 Signal optical waveguide 20T Inspection optical waveguide 21 First cladding layer 22a, 22b, 22c, 22d Signal core layer 22t Inspection core layer 23 Second cladding layer 30 Silicon Photonics Chip 40 Connectors 50 Wiring board 110 Light emitting part 120 Light receiving section

Claims

1. A first cladding layer; a plurality of core layers formed on the first clad layer; a second clad layer formed on the first clad layer and selectively covering the core layer; a first region not covered by the second clad layer is provided on the first clad layer; The plurality of core layers include a plurality of signal core layers, one end of which is disposed in the first region and which input and output signal light; an inspection core layer having one end and the other end exposed to an outer peripheral surface and adapted to input and output inspection light; the inspection core layer is formed of the same material as the signal core layer, An optical waveguide device, wherein a cross-sectional shape in the short side direction of the inspection core layer is the same as a cross-sectional shape in the short side direction of the signal core layer.

2. the first cladding layer has four or more sides in a plan view, 2 . The optical waveguide device according to claim 1 , wherein a side on which at least one end of the inspection core layer is located is different from a side on which the other end of the signal core layer is located in a plan view.

3. 3. The optical waveguide device according to claim 2, wherein, in a plan view, a side on which the other end of the inspection core layer is located is the same as a side on which the other end of the signal core layer is located.

4. A protrusion portion having a first side and a second side parallel to the first side in a plan view, In a plan view, one end of the inspection core layer is located on the first side and the other end is located on the second side, The optical waveguide device according to claim 1 , wherein a longitudinal direction of the inspection core layer is perpendicular to the first side and the second side in a plan view.

5. The optical waveguide device according to claim 1 , wherein the inspection core layer is disposed at a corner of the first cladding layer in a plan view.

6. The optical waveguide device according to claim 1 , wherein the inspection core layer includes a portion that is non-parallel to the signal core layer in a plan view.

7. A silicon photonics chip is disposed in the first region; The optical waveguide device according to claim 1 , wherein the silicon photonics chip is optically coupled to the one ends of the plurality of signal core layers.

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