Optical module

Abstract

An optical module (A1) comprises a substrate (10), a waveguide (20), an optical fiber (30), and a fixing member (40). The substrate (10) has a first groove (11) and a second groove (12). The first groove (11) extends along a first direction. The second groove (12) is connected to the first groove (11). The waveguide (20) is disposed in the first groove (11) and extends along the first direction. The optical fiber (30) is disposed in the second groove (12). The fixing member (40) includes a first fixing member (41) and a second fixing member (42), and the first fixing member (41) and the second fixing member (42) are disposed in the second groove (12). The optical fiber (30) is disposed between the first fixing member (41) and the second fixing member (42). One end of the optical fiber (30) faces one end of the waveguide (20). The substrate (10) further has a third groove (13). The third groove (13) is positioned in the first direction when viewed from the first fixing member (41), and is connected to the second groove (12).

Description

Optical module

[0001] The present disclosure generally relates to optical modules, and more particularly to an optical module including a waveguide.

[0002] An example is the optical module described in Patent Document 1. The optical module includes a substrate, an internal waveguide, an optical fiber, and two optical fiber positioning members. The substrate has a first groove and a second groove connected to the first groove. The internal waveguide is disposed in the first groove. The two optical fiber positioning members are disposed in the second groove. The optical fiber is sandwiched between the two optical fiber positioning members in the second groove.

[0003] In the above optical module, a pressing block is disposed at the tip of the optical fiber, and the space between the pressing block and the second groove is filled with an optical adhesive. Further, in the above optical module, with the tip of the optical fiber pressed against the second groove by the pressing block, the tip is fixed to the substrate together with the pressing block by the optical adhesive.

[0004] Japanese Unexamined Patent Publication No. 2013-057721

[0005] In the optical module described in Patent Document 1, the second groove is filled with the optical adhesive; however, if an air layer (for example, an air bubble in the optical adhesive) is present in the optical path between the optical fiber and the internal waveguide, communication performance may deteriorate.

[0006] An optical module according to one aspect of the present disclosure comprises a substrate, a waveguide, an optical fiber, and a fixing member. The substrate has a first groove and a second groove. The first groove extends along a first direction. The second groove is connected to the first groove. The waveguide is located in the first groove. The waveguide extends along the first direction. The optical fiber is located in the second groove. The optical fiber is optically coupled to the waveguide. The fixing member sandwiches the optical fiber. The depth of the second groove is greater than the depth of the first groove. The fixing member includes a first fixing member and a second fixing member. The first fixing member is located in the second groove. The second fixing member is located in the second groove. The optical fiber is located between the first fixing member and the second fixing member. One end of the optical fiber faces one end of the waveguide. The substrate further has a third groove. The third groove is located in the first direction when viewed from the first fixing member. The third groove is connected to the second groove.

[0007] An optical module according to one aspect of the present disclosure comprises a substrate, a waveguide, and a first fixing member. The substrate has a first groove and a second groove. The first groove extends along a first direction. The second groove is connected to the first groove. The waveguide is positioned in the first groove. The waveguide extends along the first direction. The first fixing member is positioned in the second groove. The first fixing member is positioned in a direction intersecting the first direction as viewed from the waveguide. The depth of the second groove is greater than the depth of the first groove. The substrate further has a third groove. The third groove is positioned in the first direction as viewed from the first fixing member. The third groove is connected to the second groove.

[0008] According to one aspect of this disclosure, the degradation of communication performance can be reduced.

[0009] Figure 1 is a plan view of an optical module according to Embodiment 1. Figure 2 is a cross-sectional view of the same optical module, broken along the line X1-X1 in Figure 1. Figure 3 is a side view of the same optical module, partially broken along the line Y1-Y1 in Figure 1. Figure 4 is a side view of the same optical module, partially broken along the line Z1-Z1 in Figure 1. Figure 5 is a plan view of an optical module according to a modified example of Embodiment 1. Figure 6 is a side view of the same optical module, partially broken along the line Z2-Z2 in Figure 5. Figure 7 is a plan view of an optical module according to another modified example of Embodiment 1. Figure 8 is a side view of the same optical module, partially broken along the line Z3-Z3 in Figure 7. Figure 9 is a plan view of an optical module according to Embodiment 2. Figure 10 is a cross-sectional view of the same optical module, broken along the line X2-X2 in Figure 9. Figure 11 is a side view of the same optical module, partially broken along the line Y2-Y2 in Figure 9. Figure 12 is a partially broken side view of an optical module according to a modified example of Embodiment 2. Figure 13 is a partially broken side view of an optical module according to another modified example of Embodiment 2.

[0010] The optical modules according to Embodiments 1 and 2 will be described below with reference to the drawings. The figures described in each embodiment below are schematic diagrams, and the ratios of the size and thickness of each component do not necessarily reflect the actual dimensional ratios. Furthermore, the configurations described in each embodiment are merely examples of the present disclosure. The present disclosure is not limited to each embodiment, and various modifications are possible depending on the design, etc., as long as the effects of the present disclosure can be achieved. Furthermore, the present disclosure can also be applied by appropriately combining at least some of the configurations of each embodiment and each modified example below.

[0011] In the following explanation, unless otherwise specified, the first direction D1, second direction D2, and third direction D3 indicated by arrows in the drawings are defined as the front-to-back, left-to-right, and up-and-down directions of the optical module. However, the front-to-back, left-to-right, and up-and-down directions of the optical module do not necessarily correspond to the directions in which the optical module is used. Also, the arrows indicating "D1," "D2," and "D3" in the drawings are for illustrative purposes only and do not represent actual objects.

[0012] (Embodiment 1) The optical module according to Embodiment 1 will be described below with reference to Figures 1 to 4.

[0013] (1) Optical module Embodiment 1's optical module A1 is used, for example, as a transmitting optical module that transmits optical signals.

[0014] The optical module A1 comprises a substrate 10, a plurality of waveguides 20 (two in the example in Figure 1), a plurality of optical fibers 30 (two in the example in Figure 1), and a plurality of fixing members 40 (three in the example in Figure 1).

[0015] Since the configuration and function of each of the multiple waveguides 20 are common, unless otherwise specified, one waveguide 20 will be described below. Similarly, since the configuration and function of each of the multiple optical fibers 30 are common, unless otherwise specified, one optical fiber 30 will be described below. Similarly, since the configuration and function of each of the multiple fixing members 40 are common, unless otherwise specified, one fixing member 40 will be described below.

[0016] (2) Components of the optical module (2.1) Substrate The substrate 10 is a plate-shaped (rectangular plate-shaped in the example of Figure 1) silicon substrate. The substrate 10 has a plurality of (two in the example of Figure 1) first grooves 11, 14 and a second groove 12. Since the configuration of each of the plurality of first grooves 11, 14 is the same, unless otherwise specified below, the first groove 11 will be described and the description of the first groove 14 may be omitted. Also, below, in order to distinguish it from the first groove 11, the first groove 14 will be referred to as the "fourth groove 14".

[0017] The first groove 11 is formed in the substrate 10 along a first direction (front-to-back direction) D1 of the substrate 10. More specifically, the first groove 11 is formed along the front-to-back direction D1 of the substrate 10 on the surface 10a side of the substrate 10. That is, the first groove 11 extends along the front-to-back direction D1. As shown in Figure 2, the cross-sectional shape of the first groove 11 from the front-to-back direction D1 is trapezoidal.

[0018] As shown in Figure 1, the fourth groove 14 is parallel to the first groove 11. That is, the fourth groove 14 is formed in the substrate 10 along the front-to-back direction D1 of the substrate 10.

[0019] In the following, in the front-to-back direction D1 of the optical module A1 shown in Figure 1, the side of the second groove 12 as viewed from the first groove 11 is defined as "front," and the opposite side is defined as "rear." Also, in the second direction (left-to-right direction) D2 of the optical module A1, the side of the first groove 11 as viewed from the fourth groove 14 is defined as "left," and the opposite side is defined as "right." Furthermore, in the third direction (up-down direction) D3 of the optical module A1 shown in Figure 2, the surface 10a of the substrate 10 is defined as "up," and the back surface opposite to the surface 10a is defined as "down." However, the front, rear, left, right, up, and down of the optical module A1 do not necessarily refer to the orientation when the optical module A1 is used.

[0020] The second groove 12 is formed in the substrate 10 along the front-to-back direction D1 so as to connect with the multiple first grooves 11 and 14. In other words, the second groove 12 is formed in the substrate 10 in a continuous manner with the multiple first grooves 11 and 14. As shown in Figure 3, the cross-sectional shape of the second groove 12 in the front-to-back direction D1 is rectangular.

[0021] The depth d2 of the second groove 12 in the vertical direction D3 is deeper than the depth d1 of the first groove 11 in the vertical direction D3 (see Figure 2). The width W2 of the second groove 12 in the horizontal direction D2 is greater than the width W1 of the first groove 11 in the horizontal direction D2 (see Figure 2). Furthermore, the width W2 of the second groove 12 is greater than the sum of the width W1 of the first groove 11 and the width W5 of the fourth groove 14 in the horizontal direction D2 (see Figure 2).

[0022] (2.2) Waveguide The waveguide 20 shown in Figure 1 is through which light propagates. The material of the waveguide 20 is a light-transmitting material (for example, resin, glass, etc.). As shown in Figure 2, the waveguide 20 has a core 1 and a cladding 2.

[0023] Light propagates through core 1. Core 1 has a rectangular parallelepiped shape. The cross-sectional shape of core 1 in the front-to-back direction D1 is square.

[0024] Core 1 is positioned at the bottom of the first groove 11 along the front-to-back direction D1 of the waveguide 20, and also at the center of the first groove 11 in the left-to-right direction D2. The height of core 1 in the vertical direction D3 is the same as the depth d1 of the first groove 11. The width of core 1 in the left-to-right direction D2 is smaller than the width W1 of the first groove 11. More specifically, the width of core 1 in the left-to-right direction D2 is smaller than the width of the bottom of the first groove 11 in the left-to-right direction D2.

[0025] Furthermore, the statement "the height D3 of core 1 is the same as the depth d1 of the first groove 11" is not limited to the case where the difference (absolute value of the difference) between the height D3 of core 1 and the depth d1 of the first groove 11 is 0, but also includes, for example, the case where the difference between the height D3 of core 1 and the depth d1 of the first groove 11 is 10% or less of the depth d1 of the first groove 11.

[0026] Cladding 2 covers the core 1 and the first groove 11. In other words, cladding 2 covers the core 1 located in the first groove 11 and also covers the opening of the first groove 11. The height D3 of cladding 2 in the vertical direction is greater than the depth d1 of the first groove 11. The maximum width D2 of cladding 2 in the horizontal direction is the same as the width W1 of the first groove 11. The refractive index of cladding 2 is lower than that of core 1.

[0027] Furthermore, the statement "the maximum width D2 of the cladding 2 is the same as the width W1 of the first groove 11" is not limited to the case where the difference (absolute value of the difference) between the maximum width of the cladding 2 and the width W1 of the first groove 11 is 0, but also includes, for example, the case where the difference between the maximum width of the cladding 2 and the width W1 of the first groove 11 is 10% or less of the width W1 of the first groove 11.

[0028] As shown in Figure 1, the plurality of waveguides 20 include a first waveguide 21 and a second waveguide 22. The first waveguide 21 is located in a first groove 11 along the front-to-back direction D1 of the substrate 10. That is, the first waveguide 21 extends along the front-to-back direction D1. The second waveguide 22 is located in a fourth groove 14 along the front-to-back direction D1 of the substrate 10. That is, the second waveguide 22 extends along the front-to-back direction D1.

[0029] (2.3) Optical Fiber The optical fiber 30 is optically coupled to the waveguide 20. As shown in Figure 3, the optical fiber 30 is placed in the second groove 12. The optical fiber 30 also has a core 3 and a cladding 4. Light propagates through the core 3. The refractive index of the cladding 4 is lower than that of the core 3.

[0030] As shown in Figure 1, the optical fiber 30 is positioned between a plurality of (two in the example of Figure 1) fixing members 40 such that one end (rear end) 30a of the optical fiber 30 faces one end (front end) 20a of the waveguide 20 in the front-to-back direction D1.

[0031] Furthermore, the optical fiber 30 is arranged between a plurality of fixing members 40 such that the optical fiber 30 is aligned in the front-to-back direction D1.

[0032] The multiple optical fibers 30 include a first optical fiber 31 and a second optical fiber 32.

[0033] (2.4) Fixing Member The fixing member 40 shown in Figure 1 is a member for positioning the optical fiber 30 on the substrate 10. The material of the fixing member 40 is, for example, resin. The fixing member 40 is located in the second groove 12. For example, the fixing member 40 is located in the second groove 12 along the front-rear direction D1 of the substrate 10. That is, the fixing member 40 is separate from the substrate 10 and is attached to the second groove 12 of the substrate 10.

[0034] The multiple fixing members 40 include a first fixing member 41, a second fixing member 42, and a third fixing member 43.

[0035] The first fixing member 41 and the second fixing member 42 are positioned in a direction that intersects the front-rear direction D1 (in the example of Figure 1, the left-right direction D2) when viewed from the first waveguide 21. For example, the second fixing member 42 faces the first fixing member 41 in the left-right direction D2 of the substrate 10. Note that the "direction that intersects the front-rear direction D1" is not limited to the left-right direction D2 which is perpendicular to the front-rear direction D1.

[0036] The second fixing member 42 and the third fixing member 43 are positioned in a direction intersecting the front-rear direction D1 (in the example of Figure 1, the left-right direction D2) when viewed from the second waveguide 22. For example, the third fixing member 43 faces the second fixing member 42 in the left-right direction D2 of the substrate 10.

[0037] The first fixing member 41 and the second fixing member 42 sandwich the first optical fiber 31 from both sides in the left-right direction D2 of the substrate 10. The second fixing member 42 and the third fixing member 43 sandwich the second optical fiber 32 from both sides in the left-right direction D2 of the substrate 10. In other words, the first optical fiber 31 is positioned between the first fixing member 41 and the second fixing member 42. The second optical fiber 32 is positioned between the second fixing member 42 and the third fixing member 43.

[0038] Incidentally, the substrate 10 further has multiple (three in the example shown in Figure 1) third grooves 13. Since the configuration and function of each of the multiple third grooves 13 are the same, unless otherwise specified, only one third groove 13 will be described below.

[0039] The third groove 13 is formed in the substrate 10 so as to connect with the second groove 12. In other words, the third groove 13 is formed in the substrate 10 in a continuous manner with the second groove 12. As shown in Figure 2, the cross-sectional shape of the third groove 13 from the front-to-back direction D1 is V-shaped. That is, the third groove 13 opens upward.

[0040] Furthermore, as shown in Figure 1, the third groove 13 is located in the front-rear direction D1 when viewed from one of the multiple fixing members 40 (for example, the first fixing member 41). Also, the third groove 13 is formed near the first fixing member 41, the second fixing member 42, or the third fixing member 43. For example, the third groove 13 is formed near one of the multiple fixing members 40 (for example, the first fixing member 41) such that the distance between the third groove 13 and one of the multiple fixing members 40 is less than or equal to a predetermined distance (for example, the width W4 of the gap 50 described later). In other words, "near the fixing member 40" means when the distance between the third groove 13 and the fixing member 40 is less than or equal to the predetermined distance.

[0041] The third groove 13 is formed in the substrate 10 along the front-rear direction D1 of the substrate 10. In other words, the third groove 13 is formed in the substrate 10 so as to be parallel to at least one of the first groove 11 and the fourth groove 14.

[0042] Further, the third groove 13 is formed in the substrate 10 such that one end (front end) 13a of the third groove 13 in the front-rear direction D1 faces the first fixing member 41, the second fixing member 42, or the third fixing member 43 in the front-rear direction D1. For example, the third groove 13 is formed in the substrate 10 such that the front end 13a of the third groove 13 faces one end (rear end) 40a of the fixing member 40 (e.g., the first fixing member 41) in the front-rear direction D1. That is, the front end 13a of the third groove 13 is aligned with the first fixing member 41, the second fixing member 42, or the third fixing member 43 in the front-rear direction D1.

[0043] Here, in the second groove 12 of the substrate 10, a gap 50 is provided between the front end 13a of the third groove 13 and the rear end 40a of the fixing member 40. The gap 50 is formed when the fixing member 40 is attached to the second groove 12 of the substrate 10.

[0044] A depth d3 of the third groove 13 in the up-down direction D3 (see FIG. 4) is shallower than a depth d2 of the second groove 12 (see FIG. 3). More specifically, the depth d3 at the deepest position in the third groove 13 is shallower than the depth d2 of the second groove 12.

[0045] Further, the depth d3 of the third groove 13 is shallower than a depth d1 of the first groove 11 (see FIG. 2). More specifically, the depth d3 at the deepest position in the third groove 13 is shallower than the depth d1 of the first groove 11.

[0046] As shown in FIG. 1, the plurality of third grooves 13 include a third groove 131, a third groove 132, and a third groove 133. One third groove 132 among the plurality of third grooves 131 to 133 is disposed between the plurality of first grooves 11 and 14.

[0047] (3) Assembly Procedure of Optical Module Next, the assembly procedure of optical module A1 will be described. In the following description, a case where a plurality of first grooves 11 and 14, a second groove 12, and a plurality of third grooves 13 are pre-formed on the substrate 10, the first waveguide 21 is disposed in the first groove 11, the second waveguide 22 is disposed in the fourth groove 14, and a plurality of fixing members 40 are attached to the second groove 12 will be described.

[0048] First, an operator performing assembly work applies an adhesive (for example, UV adhesive) into the second groove 12 of the substrate 10. The adhesive is used to fix the plurality of optical fibers 30 to the substrate 10, and has light transmittance and high viscosity. In FIGS. 1, 3 and 4, the illustration of said adhesive is omitted.

[0049] Then, the operator presses the first optical fiber 31 between the first fixing member 41 and the second fixing member 42, and disposes the first optical fiber 31 between the first fixing member 41 and the second fixing member 42. In addition, the operator presses the second optical fiber 32 between the second fixing member 42 and the third fixing member 43, and disposes the second optical fiber 32 between the second fixing member 42 and the third fixing member 43.

[0050] In addition, the operator further applies said adhesive to the second groove 12 in which the first optical fiber 31 and the second optical fiber 32 are disposed.

[0051] Finally, the operator presses a pressing member (for example, pressing glass, etc.) against the first optical fiber 31 and the second optical fiber 32 from above the second groove 12 of the substrate 10, and cures said adhesive in this state. In FIGS. 1, 3 and 4, the illustration of the pressing member is omitted.

[0052] The assembly of the optical module A1 is completed through the above procedure. It should be noted that the above assembly procedure is an example, and several additional procedures may be added without any problem.

[0053] (4) Effects In the optical module A1 of Embodiment 1, when the adhesive is applied to the second groove 12 of the substrate 10, the adhesive may not penetrate into the gap 50 of the second groove 12, and air bubbles (air layers) may remain in the gap 50. For this reason, in the optical module A1, a third groove 13 is formed in the substrate 10 to allow the air bubbles to escape from the gap 50 when the pressing member is pressed against the first optical fiber 31 and the second optical fiber 32.

[0054] In other words, the substrate 10 of the optical module A1 of Embodiment 1 has a third groove 13, the third groove 13 is located in the front-to-back direction D1 when viewed from the first fixing member 41, the second fixing member 42, or the third fixing member 43, and is connected to the second groove 12. As a result, in the optical module A1, after fixing the multiple optical fibers 30 to the substrate 10 with the adhesive, it is possible to reduce the amount of air bubbles remaining in the optical path between the front end 20a of the waveguide 20 and the rear end 30a of the optical fiber 30. Therefore, in the optical module A1, the reflection of light transmitted from the front end 20a of the waveguide 20 to the rear end 30a of the optical fiber 30 by the air bubbles can be reduced, thus reducing the degradation of communication performance.

[0055] The third groove 13 is formed in the substrate 10 so as to follow the front-to-back direction D1 of the substrate 10. The front end 13a of the third groove 13 is aligned with the first fixing member 41, the second fixing member 42, or the third fixing member 43 in the front-to-back direction D1. As a result, in the optical module A1, when the pressing member is pressed against the first optical fiber 31 and the second optical fiber 32, the air bubbles can easily enter the third groove 13 from the gap 50 of the second groove 12. Therefore, in the optical module A1, the amount of air bubbles remaining in the optical path between the front end 20a of the waveguide 20 and the rear end 30a of the optical fiber 30 can be further reduced, thereby further reducing the degradation of communication performance.

[0056] The third groove 13 is located between the first groove 11 and the fourth groove 14. This makes it easier for bubbles generated in the optical module A1 to escape into the third groove 13 when the first waveguide 21 located in the first groove 11 and the first optical fiber 31 are optically coupled with the adhesive, and when the second waveguide 22 located in the fourth groove 14 and the second optical fiber 32 are optically coupled with the adhesive. Therefore, in the optical module A1, the amount of bubbles remaining in both the optical path between the first waveguide 21 and the first optical fiber 31 and the optical path between the second waveguide 22 and the second optical fiber 32 can be reduced, thereby further reducing the degradation of communication performance.

[0057] The depth d3 of the third groove 13 is shallower than the depth d2 of the second groove 12. This makes it easier to form the third groove 13 between the first groove 11 and the fourth groove 14 in the optical module A1, even when the space between the first groove 11 and the fourth groove 14 is narrow.

[0058] (5) Modified example The depth d3 of the third groove 13 is shallower than the depth d1 of the first groove 11, but may be deeper than the depth d1 of the first groove 11, or it may be the same as the depth d1 of the first groove 11. "The depth d3 of the third groove 13 is the same as the depth d1 of the first groove 11" is not limited to the case where the difference (absolute value of the difference) between the depth d3 of the third groove 13 and the depth d1 of the first groove 11 is 0, but also includes, for example, the case where the difference between the depth d3 of the third groove 13 and the depth d1 of the first groove 11 is 10% or less of the depth d1 of the first groove 11.

[0059] As shown in Figure 5, the width W3 of the third groove 13 along the left-right direction D2 of the substrate 10 may gradually decrease from the front end 13a to the rear end 13b in the front-rear direction D1 of the third groove 13. In other words, the width W3 of the third groove 13 may gradually increase from the rear end 13b to the front end 13a of the third groove 13. This makes it easier for the air bubbles to enter the third groove 13 from the gap 50 of the second groove 12 when the pressing member is pressed against the first optical fiber 31 and the second optical fiber 32 in the optical module A1. Therefore, the degradation of communication performance can be further reduced in the optical module A1.

[0060] Furthermore, as shown in Figure 6, the depth d3 of the third groove 13 may gradually become shallower from the front end 13a to the rear end 13b of the third groove 13. In other words, the depth d3 of the third groove 13 may gradually become deeper from the rear end 13b to the front end 13a of the third groove 13. This makes it easier for the air bubbles to enter the third groove 13 from the gap 50 in the second groove 12 when the pressing member is pressed against the first optical fiber 31 and the second optical fiber 32 in the optical module A1. Therefore, the degradation of communication performance can be further reduced in the optical module A1.

[0061] As shown in Figure 7, the width W3 of the third groove 13 may gradually increase from the front end 13a to the rear end 13b. In other words, the width W3 of the third groove 13 may gradually decrease from the rear end 13b to the front end 13a. This makes it possible to prevent air bubbles that have entered the third groove 13 from returning to the gap 50 of the second groove 12 when fixing the optical fiber 30 to the substrate 10 with the adhesive in the optical module A1 (especially when curing the adhesive). Therefore, the degradation of communication performance can be further reduced in the optical module A1.

[0062] Furthermore, as shown in Figure 8, the depth d3 of the third groove 13 may gradually increase from the front end 13a to the rear end 13b of the third groove 13. In other words, the depth d3 of the third groove 13 may gradually decrease from the rear end 13b to the front end 13a of the third groove 13. This makes it possible to further suppress the return of air bubbles that have entered the third groove 13 to the gap 50 of the second groove 12 when the optical fiber 30 is fixed to the substrate 10 with the adhesive in the optical module A1. Therefore, the degradation of communication performance can be further reduced in the optical module A1.

[0063] The width W3 of the third groove 13 in the left-right direction D2, as shown in Figure 2, is preferably greater than the width W4 of the gap 50 in the front-rear direction D1 (see Figure 1). More specifically, the width D2 of the front end 13a of the third groove 13 is preferably greater than the width W4 of the gap 50. This makes it easier for the air bubbles to enter the third groove 13 from the gap 50 of the second groove 12 when the pressing member is pressed against the first optical fiber 31 and the second optical fiber 32 in the optical module A1. Therefore, in the optical module A1, the degradation of communication performance can be reduced compared to when the width W3 of the third groove 13 is smaller than or the same as the width W4 of the gap 50.

[0064] The cross-sectional shape of the third groove 13 is not limited to a V-shape; for example, it may be trapezoidal, rectangular, or other shapes. The depth d3 of the third groove 13 is shallower than the depth d2 of the second groove 12, but may be the same as the depth d2 of the second groove 12. Note that "the depth d3 of the third groove 13 is the same as the depth d2 of the second groove 12" does not only mean that the difference (absolute value of the difference) between the depth d3 of the third groove 13 and the depth d2 of the second groove 12 is 0, but also includes, for example, the case where the difference between the depth d3 of the third groove 13 and the depth d2 of the second groove 12 is 10% or less of the depth d2 of the second groove 12.

[0065] One of the multiple third grooves 13 is positioned between the multiple first grooves 11 and 14, but it does not have to be positioned between the multiple first grooves 11 and 14.

[0066] The number of third grooves 13 is not limited to three; it may be one, two, or four or more. The number of waveguides 20 is not limited to two; it may be three or more, or one. The number of optical fibers 30 is not limited to two; it may be three or more, or one. The number of fixing members 40 is not limited to three; it may be four or more, or two or fewer.

[0067] The optical module A1 includes multiple optical fibers 30, but it does not have to include multiple optical fibers 30. In other words, the optical module A1 only needs to include a substrate 10, multiple waveguides 20, and multiple fixing members 40. Even with this configuration, the degradation of communication performance can be reduced in the optical module A1.

[0068] Furthermore, the optical module A1 may further comprise the adhesive and a retaining member. The optical module A1 may further comprise one or more optical devices (e.g., light-emitting elements) and one or more mirror portions. In this case, the optical device is positioned at the rear end of the waveguide 20 opposite the front end 20a, with one side of the optical device (e.g., the light-emitting surface) facing the substrate 10. The mirror portion is positioned at the rear end of the waveguide 20, for example, so as to bend the optical path of light from the optical device by 90 degrees. That is, the mirror portion is positioned directly below the aforementioned one side of the optical device.

[0069] Optical module A1 is used as a transmitting optical module, but it may also be used as a receiving optical module. In other words, the optical device may be a photodetector.

[0070] (Embodiment 2) The optical module A2 according to Embodiment 2 differs from the optical module A1 according to Embodiment 1 (see Figure 1) in that the substrate 10 has a third groove 15, as shown in Figure 9.

[0071] With respect to the optical module A2 according to Embodiment 2, components similar to those in the optical module A1 according to Embodiment 1 are denoted by the same reference numerals and their descriptions are omitted.

[0072] The optical module A2 according to Embodiment 2 will be described below with reference to Figures 9 to 11.

[0073] (1) The optical module A2 of the optical module embodiment 2 comprises a substrate 10, a plurality of waveguides 20 (two in the example of Figure 9), a plurality of optical fibers 30 (two in the example of Figure 9), and a plurality of fixing members 40 (three in the example of Figure 9). The optical module A2 of embodiment 2 is used, for example, as a transmitting optical module that transmits optical signals.

[0074] (2) Each component substrate 10 of the optical module further has a plurality (three in the example of Figure 9) of third grooves 15. Since the configuration of each of the plurality of third grooves 15 is common, unless otherwise specified, one third groove 15 will be described below.

[0075] As shown in Figure 11, the third groove 15 is formed in the substrate 10 so as to connect with the second groove 12. That is, the third groove 13 is formed in the substrate 10 in a continuous manner with the second groove 12. Also, as shown in Figure 11, the third groove 15 is connected to the second groove 12 such that the bottom surface 15a of the third groove 15 is located below the bottom surface 12a of the second groove 12. The cross-sectional shape of the third groove 15 from the front-to-back direction D1 is a quadrilateral (for example, a rectangle). The third groove 15 opens upwards. Note that the cross-sectional shape of the third groove 15 from the front-to-back direction D1 is not limited to a quadrilateral, but may also be a triangular (for example, an equilateral triangle).

[0076] Furthermore, as shown in Figures 9 and 11, the third groove 15 is formed on the bottom surface 12a of the second groove 12 between the boundary 60 between the plurality of first grooves 11, 14 and the second groove 12, and the first fixing member 41, the second fixing member 42, or the third fixing member 43. In other words, the third groove 15 is formed near the first fixing member 41, the second fixing member 42, or the third fixing member 43, and is located between the boundary 60 and the first fixing member 41, the second fixing member 42, or the third fixing member 43.

[0077] In this embodiment, the boundary 60 is the inner surface of the second groove 12 located at the boundary between the plurality of first grooves 11, 14 and the second groove 12. Also in this embodiment, the distance between the boundary (the inner surface of the second groove 12) 60 and the rear end 40a of the fixing member 40 (i.e., the width W4 of the gap 50) is greater than or equal to the distance between the boundary 60 and the rear end 30a of the optical fiber 30 (for example, 60 μm).

[0078] (3) Effect The third groove 15 is located between the boundary 60 between the multiple first grooves 11, 14 and the second groove 12, and the first fixing member 41, the second fixing member 42, or the third fixing member 43, and is formed on the bottom surface 12a of the second groove 12. As a result, in the optical module A2, when the pressing member is pressed against the first optical fiber 31 and the second optical fiber 32, the air bubbles can easily enter the third groove 15 from the gap 50 in the second groove 12. Therefore, in the optical module A2, the amount of air bubbles remaining in the optical path between the front end 20a of the waveguide 20 and the rear end 30a of the optical fiber 30 can be further reduced, and thus the degradation of communication performance can be further reduced.

[0079] (4) Modified Example The cross-sectional shape of the third groove 15 in the front-to-back direction D1 is rectangular, but it may also be trapezoidal or the like. For example, as shown in Figure 12, the width W6 of the third groove 15 in the left-to-right direction D2 may gradually increase from the bottom surface 15a of the third groove 15 upwards. This makes it easier for the air bubbles to enter the third groove 15 from the gap 50 of the second groove 12 when the pressing member is pressed against the first optical fiber 31 and the second optical fiber 32 in the optical module A2. Therefore, the degradation of communication performance can be further reduced in the optical module A2. Note that "width W6 of the third groove 15" means the distance between a pair of inner surfaces facing each other in the left-to-right direction D2 in the third groove 15. Also, "W6" in Figure 12 indicates the largest width of the width W6 of the third groove 15.

[0080] Furthermore, as shown in Figure 13, the width W6 of the third groove 15 may gradually decrease from the bottom surface 15a of the third groove 15 upwards. This prevents air bubbles that have entered the third groove 15 from returning to the gap 50 of the second groove 12 when fixing the optical fiber 30 to the substrate 10 with the adhesive (especially when curing the adhesive) in the optical module A2. Therefore, the degradation of communication performance can be further reduced in the optical module A2. Note that "W6" in Figure 13 indicates the largest width of the width W6 of the third groove 15.

[0081] (Aspects) The following aspects are disclosed in this specification.

[0082] An optical module (A1; A2) according to the first embodiment comprises a substrate (10), a waveguide (20), an optical fiber (30), and a fixing member (40). The substrate (10) has a first groove (11) and a second groove (12). The first groove (11) extends along a first direction (D1). The second groove (12) is connected to the first groove (11). The waveguide (20) is located in the first groove (11). The waveguide (20) extends along the first direction (D1). The optical fiber (30) is located in the second groove (12). The optical fiber (30) is optically coupled to the waveguide (20). The fixing member (40) sandwiches the optical fiber (30). The depth (d2) of the second groove (12) is greater than the depth (d1) of the first groove (11). The fixing member (40) includes a first fixing member (41) and a second fixing member (42). The first fixing member (41) is located within the second groove (12). The second fixing member (42) is located within the second groove (12). The optical fiber (30) is located between the first fixing member (41) and the second fixing member (42). One end (30a) of the optical fiber (30) faces one end (20a) of the waveguide (20). The substrate (10) further has a third groove (13;15). The third groove (13;15) is located in a first direction (D1) as viewed from the first fixing member (41). The third groove (13;15) is connected to the second groove (12).

[0083] This embodiment can reduce the degradation of communication performance.

[0084] An optical module (A1; A2) according to a second embodiment comprises a substrate (10), a waveguide (20), and a first fixing member (41). The substrate (10) has a first groove (11) and a second groove (12). The first groove (11) extends along a first direction (D1). The second groove (12) is connected to the first groove (11). The waveguide (20) is located in the first groove (11). The waveguide (20) extends along the first direction (D1). The first fixing member (41) is located in the second groove (12). The first fixing member (41) is located in a direction intersecting the first direction (D1) when viewed from the waveguide (20). The depth (d2) of the second groove (12) is greater than the depth (d1) of the first groove (11). The substrate (10) further has third grooves (13; 15). The third grooves (13; 15) are located in a first direction (D1) when viewed from the first fixing member (41). The third grooves (13; 15) are connected to the second groove (12).

[0085] This embodiment can reduce the degradation of communication performance.

[0086] In the third embodiment of the optical module (A1), in the first or second embodiment, the third groove (13) is aligned with the first direction (D1) of the substrate (10). One end (13a) of the third groove (13) is aligned with the first fixing member (41) in the first direction (D1).

[0087] This embodiment can further reduce the degradation of communication performance.

[0088] In the fourth embodiment, the optical module (A1) further has a substrate (10) having a fourth groove (14) in the third embodiment. The fourth groove (14) is parallel to the first groove (11). The third groove (13) is located between the first groove (11) and the fourth groove (14).

[0089] According to this embodiment, the degradation of communication performance can be further reduced.

[0090] In the fifth embodiment of the optical module (A1), in the third or fourth embodiment, the width (W3) of the third groove (13) along the second direction (D2) perpendicular to the first direction (D1) of the substrate (10) decreases from one end (13a) of the third groove (13) to the other end (13b) of the third groove (13).

[0091] According to this embodiment, the degradation of communication performance can be further reduced.

[0092] In the sixth embodiment of the optical module (A1), the depth (d3) of the third groove (13) that opens upward is shallower from one end (13a) to the other end (13b) of the third groove (13).

[0093] According to this embodiment, the degradation of communication performance can be further reduced.

[0094] In the optical module (A1) according to the seventh embodiment, in the third or fourth embodiment, the width (W3) of the third groove (13) along the second direction (D2) perpendicular to the first direction (D1) of the substrate (10) increases from one end (13a) of the third groove (13) to the other end (13b) of the third groove (13).

[0095] According to this embodiment, the degradation of communication performance can be further reduced.

[0096] In the optical module (A1) according to the eighth embodiment, in the seventh embodiment, the depth (d3) of the third groove (13) that opens upward is increased from one end (13a) of the third groove (13) to the other end (13b).

[0097] According to this embodiment, the degradation of communication performance can be further reduced.

[0098] In the optical module (A1) according to the ninth embodiment, in any one of the third to eighth embodiments, the depth (d3) of the third groove (13) that opens upward is shallower than the depth (d2) of the second groove (12).

[0099] According to this embodiment, for example, it becomes easier to form a third groove (13) between the first groove (11) and the first groove (14).

[0100] In the tenth embodiment of the optical module (A2), in the first or second embodiment, the third groove (15) is located between the boundary (60) of the first groove (11) and the second groove (12) and the first fixing member (41). The third groove (15) is formed on the bottom surface (12a) of the second groove (12).

[0101] This embodiment can further reduce the degradation of communication performance.

[0102] In the 11th embodiment, the optical module (A2) is such that, in the 10th embodiment, the width (W6) of the third groove (15) that opens upward in a second direction (D2) perpendicular to the first direction (D1) of the third groove (15) increases upward from the bottom surface (15a) of the third groove (15).

[0103] According to this embodiment, the degradation of communication performance can be further reduced.

[0104] In the optical module (A2) according to the twelfth embodiment, in the tenth embodiment, the width (W6) of the third groove (15) that opens upward in a second direction (D2) perpendicular to the first direction (D1) is smaller from the bottom surface (15a) of the third groove (15) upward.

[0105] According to this embodiment, the degradation of communication performance can be further reduced.

[0106] 10 Substrate 11 First groove 12 Second groove 12a Bottom surface 13 Third groove 13a One end 13b Rear end (other end) 14 First groove (fourth groove) 15 Third groove 15a Bottom surface 20 Waveguide 20a One end 30 Optical fiber 30a One end 40 Fixing member 41 First fixing member 42 Second fixing member 60 Boundary A1-A2 Optical module D1 First direction D2 Second direction d1 Depth d2 Depth d3 Depth W3 Width W6 Width

Claims

1. An optical module comprising: a substrate having a first groove extending in a first direction and a second groove connected to the first groove; a waveguide disposed in the first groove and extending in the first direction; an optical fiber disposed in the second groove and optically coupled to the waveguide; and a fixing member sandwiching the optical fiber, wherein the depth of the second groove is greater than the depth of the first groove; the fixing member includes a first fixing member disposed in the second groove and a second fixing member disposed in the second groove; the optical fiber is disposed between the first fixing member and the second fixing member; one end of the optical fiber faces one end of the waveguide; and the substrate further has a third groove located as seen from the first fixing member, the third groove being connected to the second groove.

2. An optical module comprising: a substrate having a first groove extending along a first direction and a second groove connected to the first groove; a waveguide disposed in the first groove and extending along the first direction; and a first fixing member disposed in the second groove and positioned in a direction intersecting the first direction as viewed from the waveguide, wherein the depth of the second groove is greater than the depth of the first groove; and the substrate has a third groove located in the first direction as viewed from the first fixing member, the third groove being connected to the second groove.

3. The optical module according to claim 1 or claim 2, wherein the third groove is aligned with the first direction of the substrate, and one end of the third groove is aligned with the first fixing member in the first direction.

4. The optical module according to claim 3, wherein the substrate further has a fourth groove parallel to the first groove, and the third groove is located between the first groove and the fourth groove.

5. The optical module according to claim 3 or claim 4, wherein the width of the third groove along the second direction perpendicular to the first direction of the substrate decreases from one end of the third groove to the other end of the third groove.

6. The optical module according to claim 5, wherein the depth of the third groove that opens upward is shallower from one end of the third groove to the other end.

7. The optical module according to claim 3 or claim 4, wherein the width of the third groove along the second direction perpendicular to the first direction of the substrate increases from one end of the third groove to the other end of the third groove.

8. The optical module according to claim 7, wherein the depth of the third groove, which opens upward, increases from one end of the third groove to the other end.

9. The optical module according to any one of claims 3 to 8, wherein the depth of the third groove that opens upward is shallower than the depth of the second groove.

10. The optical module according to claim 1 or claim 2, wherein the third groove is located between the boundary between the first groove and the second groove and the first fixing member, and is formed on the bottom surface of the second groove.

11. The optical module according to claim 10, wherein the width of the third groove that opens upward in a second direction perpendicular to the first direction increases from the bottom surface of the third groove upward.

12. The optical module according to claim 10, wherein the width of the third groove that opens upward in a second direction perpendicular to the first direction decreases from the bottom surface of the third groove upward.

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