Optical connection structure

Abstract

An optical connection structure (1) according to one embodiment of the present invention comprises: a substrate (21) having a plurality of grooves (21c, 21d, 21j, 21k) on which a plurality of optical fibers (12b, 12c) are placed; a first lid (22); and a second lid (23) disposed at a position separated from the first lid in the first direction (D1). The plurality of grooves include first grooves (21c, 21j) and second grooves (21d, 21k) shallower than the first grooves. The substrate has a first portion (21X) facing the first lid along a third direction (D3) intersecting both the first direction and a second direction (D2) intersecting the first direction, and a second portion (21Y) facing the second lid along the third direction. In the first portion, some (12c) of the plurality of optical fibers are placed in the first grooves (21c), and the optical fibers (12b) not placed in the first groove are placed in the second groove (21d). In the second portion, the plurality of optical fibers (12b, 12c) are placed on the first grooves (21j).

Description

Optical connection structure

[0001] This disclosure relates to an optical connection structure. This application claims priority based on Japanese Application No. 2024-171225 filed on September 30, 2024, and incorporates all the descriptions described in the said Japanese application.

[0002] Patent Document 1 describes an optical wiring component and an electronic device. The optical wiring component has an optical waveguide that optically connects a multi-core fiber and a plurality of single-core fibers to each other. The optical waveguide includes a first waveguide core portion, a second waveguide core portion, a third waveguide core portion, and a fourth waveguide core portion. The first waveguide core portion and the second waveguide core portion are provided in a layer different from the third waveguide core portion and the fourth waveguide core portion. The plurality of single-core fibers are optically connected to the multi-core fiber via the first waveguide core portion, the second waveguide core portion, the third waveguide core portion, and the fourth waveguide core portion.

[0003] Patent Document 2 describes an optical component for fiber optic coupling that optically couples a multi-core fiber to a plurality of single-core fibers. The optical component for fiber optic coupling includes a laminated portion formed by laminating two optical waveguide layers each having two cores and an overclad. On one side surface of the laminated portion, one end surfaces of the cores are two-dimensionally arranged according to the core arrangement of the multi-core fiber.

[0004] Patent Document 3 describes an optical component for mounting an optical fiber. The optical component for mounting an optical fiber includes a substrate having a plurality of guide grooves on which the optical fiber is placed, and a pressing plate that presses the optical fiber disposed in the guide grooves of the substrate. The plurality of guide grooves are in a V-shaped form with the same V-angle for each other. At least any one of the plurality of guide grooves is formed with a different groove depth.

[0005] Japanese Unexamined Patent Application Publication No. 2021-113843, Japanese Unexamined Patent Application Publication No. 2011-237573, Japanese Unexamined Patent Application Publication No. 2017-3726

[0006] The optical connection structure according to this disclosure comprises a substrate having a plurality of grooves on which each of a plurality of optical fibers can be placed, each of the plurality of grooves extending along a first direction, and the plurality of grooves arranged along a second direction intersecting the first direction; a first cover that holds down a portion of the plurality of optical fibers placed in the plurality of grooves; and a second cover positioned away from the first cover in the first direction and holding down portions of the plurality of optical fibers placed in the plurality of grooves that are different from those held down by the first cover. The plurality of grooves include a first groove and a second groove that is shallower than the first groove. The substrate has a first portion facing the first cover along a third direction intersecting both the first and second directions, and a second portion facing the second cover along the third direction. In the first portion, a portion of the plurality of optical fibers is placed in the first groove, and optical fibers not placed in the first groove are placed in the second groove. In the second portion, a plurality of optical fibers are placed in the first groove.

[0007] Figure 1 is a perspective view showing an optical connection structure according to an embodiment. Figure 2 is a plan view showing an optical connection structure according to an embodiment. Figure 3 is a side view showing an optical connection structure according to an embodiment. Figure 4 is a side view of the optical connection structure according to an embodiment viewed along the first direction. Figure 5 is a side view of the optical connection structure according to an embodiment viewed from the opposite direction to that of Figure 4. Figure 6 is a perspective view showing the substrate before completion. Figure 7 is a perspective view, side view, and plan view showing the optical waveguide substrate of the optical connection structure according to an embodiment. Figure 8 is a diagram showing an example of a cross-sectional view of a multicore fiber. Figure 9 is a perspective view showing a fiber holder of the optical connection structure according to an embodiment. Figure 10 is a plan view showing an optical connection structure according to another embodiment. Figure 11 is a side view of the optical connection structure of Figure 10 viewed along the first direction. Figure 12 is a side view of the optical connection structure of Figure 10 viewed from the opposite direction to that of Figure 11. Figure 13 is a perspective view showing an optical connection structure according to yet another embodiment.

[0008] Incidentally, in optical connection structures, it is sometimes necessary to align multiple optical paths in one direction. However, if the multiple optical paths are not aligned in one direction on the first end face of the optical component, it can be difficult to align them in one direction on the second end face opposite the first end face of the optical component. This may require highly difficult machining.

[0009] The present disclosure aims to provide an optical connection structure that allows multiple optical paths to be easily aligned in one direction and that facilitates processing.

[0010] According to this disclosure, multiple optical paths can be easily aligned in one direction, and processing can be facilitated.

[0011] The embodiments of the present disclosure are described below. (1) An optical connection structure according to one embodiment comprises a substrate having a plurality of grooves on which each of a plurality of optical fibers is placed, each of the plurality of grooves extending along a first direction and the plurality of grooves arranged along a second direction intersecting the first direction; a first cover that holds down a portion of the plurality of optical fibers placed in the plurality of grooves; and a second cover positioned at a location away from the first cover in the first direction and holding down a portion of the plurality of optical fibers placed in the plurality of grooves that is different from the first cover. The plurality of grooves include a first groove and a second groove that is shallower than the first groove. The substrate has a first portion facing the first cover along a third direction intersecting both the first and second directions, and a second portion facing the second cover along the third direction. In the first portion, a portion of the plurality of optical fibers is placed in the first groove, and optical fibers not placed in the first groove are placed in the second groove. In the second portion, a plurality of optical fibers are placed in the first groove.

[0012] This optical connection structure comprises a substrate having multiple grooves, a first cover that holds down a portion of multiple optical fibers placed in the multiple grooves, and a second cover that holds down portions of the multiple optical fibers that are different from the first cover. The substrate has a first portion facing the first cover and a second portion facing the second cover. In the first portion, a portion of the multiple optical fibers is placed in the first groove, and optical fibers not placed in the first groove are placed in the second groove, which is shallower than the first groove. In the second portion, multiple optical fibers are placed in the first groove. Therefore, even if the multiple optical fibers are not aligned in one direction in the first portion of the substrate, they can be aligned in one direction in the second portion of the substrate. In the first portion, the multiple optical fibers are not aligned in a straight line because optical fibers are placed in both the first and second grooves, whereas in the second portion, the multiple optical fibers can be aligned in a straight line because each optical fiber is placed in the first groove. By forming the first and second grooves on the substrate, multiple optical fibers can be aligned in a straight line. Therefore, the optical connection structure with the substrate can be easily processed.

[0013] (2) In (1) above, the shape of the multiple grooves in the first part may be the same as the shape of the multiple grooves in the second part. In this case, the shape of the multiple grooves in the first part is the same as the shape of the multiple grooves in the second part. This makes it easy to process the substrate having the first part and the second part.

[0014] (3) In (1) or (2) above, the cross-section of the groove when cut along a plane perpendicular to the first direction may be V-shaped. The angle formed by the sides of the second groove when cut along a plane perpendicular to the first direction may be greater than the angle formed by the sides of the first groove when cut along a plane perpendicular to the first direction. In this case, the angle of the second groove, which is shallower than the first groove, is greater than the angle of the first groove. This reduces wear of the optical fiber due to the corners of the grooves contacting the outer surface of the optical fiber.

[0015] (4) In any of (1) to (3) above, the substrate may have portions in which the first groove and the second groove are arranged alternately along the second direction. In this case, the length of the substrate in the second direction, which is the direction in which the grooves are arranged, can be reduced compared to the case in which the first groove or the second groove is arranged continuously along the second direction. Since the length of the optical connection structure in the second direction can be reduced, it contributes to miniaturization of the optical connection structure.

[0016] (5) In any of (1) to (4) above, the first cover may have a contact surface into which the optical fiber placed in the first groove makes contact, and a third groove that is recessed from the contact surface and into which the optical fiber placed in the second groove enters. In this case, the first cover has a third groove into which the optical fiber placed in the second groove, which is shallower than the first groove, enters, and by having the optical fiber enter the second groove and the third groove, the length of the optical connection structure in the third direction can be reduced. Therefore, this contributes to miniaturization of the optical connection structure.

[0017] (6) In any of (1) to (5) above, the substrate may have an exposed portion between the first portion and the second portion, which is a portion in which multiple optical fibers are exposed. The exposed portion may be located in a third direction further than the end of the optical fiber in the third direction placed in the first groove. In this case, the exposed portion is located in a third direction further than the end of the optical fiber in the third direction placed in the first groove which is deeper than the second groove. Since the optical fiber does not come into contact with the exposed portion, wear of the optical fiber due to contact can be reduced.

[0018] (7) In any of (1) to (6) above, the surface located at the end of the substrate in the first direction and the surface located at the end of the second lid in the first direction may be inclined with respect to both the first and third directions.

[0019] (8) In any of (1) to (7) above, the optical connection structure may further include an optical waveguide substrate having a plurality of optical waveguides fixed to the end of the substrate in the direction opposite to the first direction and the end of the first cover in the direction opposite to the first direction, and each of the plurality of optical fibers being optically connected.

[0020] (9) In the above (8), the optical connection structure may further include a fiber holder fixed to the opposite end of the optical waveguide substrate and holding a multicore fiber having multiple cores that optically connect to each of the multiple optical waveguides.

[0021] Specific examples of optical connection structures according to the embodiments of this disclosure will be described below with reference to the drawings. This disclosure is not limited to the following examples, but is as indicated by the claims and is intended to include all modifications within the scope equivalent to the claims. In the description of the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant descriptions are omitted where appropriate. The drawings may be simplified or exaggerated in part for ease of understanding, and dimensional ratios, etc., are not limited to those indicated in the drawings.

[0022] (First Embodiment) Figure 1 is a perspective view showing an optical connection structure 1 according to the first embodiment. As shown in Figure 1, the optical connection structure 1 comprises an optical fiber array 20, an optical waveguide substrate 30, and a fiber holder 40. The fiber holder 40, the optical waveguide substrate 30, and the optical fiber array 20 are arranged in this order along the first direction D1. The optical fiber array 20 and the fiber holder 40 are each fixed to the optical waveguide substrate 30 by adhesive.

[0023] The optical connection structure 1 optically connects, for example, a multicore fiber 11 and a plurality of optical fibers 12 to each other. The multicore fiber 11 and the optical fibers 12 extend along a first direction D1. The plurality of optical fibers 12 are aligned along a second direction D2 that intersects the first direction D1. The optical fibers 12 are, for example, single-core fibers. The first direction D1 coincides with the longitudinal direction of the optical connection structure 1, and the second direction D2 coincides with the width direction of the optical connection structure 1.

[0024] The optical fiber array 20 comprises a substrate 21 having a plurality of grooves on which each of the plurality of optical fibers 12 is placed, a first cover 22 that holds down a portion of the plurality of optical fibers 12 placed in the plurality of grooves, and a second cover 23 that holds down portions of the plurality of optical fibers 12 that are different from the first cover 22. The second cover 23 is positioned away from the first cover 22 in a first direction D1. The substrate 21 has a first portion 21X that faces the first cover 22 along a third direction D3 that intersects both the first direction D1 and the second direction D2, and a second portion 21Y that faces the second cover 23 along the third direction D3.

[0025] In the following, the direction in which the substrate 21 is positioned relative to the first lid 22 (second lid 23) (third direction D3) may be referred to as down, lower, or downward, and the direction in which the first lid 22 (second lid 23) is positioned relative to the substrate 21 (opposite direction D3) may be referred to as up, upper, or upward. However, these directions are for the sake of explanation and do not limit the position or orientation of the objects. In the substrate 21, each of the multiple grooves extends along the first direction D1, and the multiple grooves are arranged along the second direction D2. The multiple grooves of the substrate 21 will be described in detail later.

[0026] Figure 2 is a plan view of the optical fiber array 20 as seen along the third direction D3. Figure 3 is a side view of the optical fiber array 20 as seen along the second direction D2. As shown in Figures 1, 2, and 3, the substrate 21 has an exposed portion 21b between the first portion 21X and the second portion 21Y, which is the portion where a plurality of optical fibers 12 are exposed. The exposed portion 21b extends in the first direction D1 and the second direction D2. The exposed portion 21b is, for example, a flat surface. However, the exposed portion 21b may also be a curved surface, and the shape of the exposed portion 21b is not particularly limited. The plurality of optical fibers 12 are separated from the exposed portion 21b. The plurality of optical fibers 12 are (slightly) bent in the direction opposite to the second direction D2 in the exposed portion 21b.

[0027] The substrate 21 has an end face 21f extending in the second direction D2 and the third direction D3 at the end opposite to the first direction D1, and an end face 21h extending in the second direction D2 and the third direction D3 at the end in the first direction D1. The first cover 22 has an end face 22b extending in the second direction D2 and the third direction D3 at the end opposite to the first direction D1, and an end face 22d extending in the second direction D2 and the third direction D3 at the end in the first direction D1.

[0028] The second cover 23 has an end face 23b extending in the second direction D2 and the third direction D3 at the end in the first direction D1, and an end face 23d extending in the second direction D2 and the third direction D3 at the end opposite to the first direction D1. The end face 21f of the substrate 21 and the end face 22b of the first cover 22 are fixed to the optical waveguide substrate 30. When viewed along the third direction D3, an exposed portion 21b is formed between the end face 22d of the first cover 22 and the end face 23d of the second cover 23. The tip surfaces of multiple optical fibers 12 are exposed on the end face 21h of the substrate 21 and the end face 23b of the second cover 23.

[0029] Figure 4 is a side view showing the end face 21f of the substrate 21 and the end face 22b of the first lid 22. As shown in Figures 1, 3, and 4, the substrate 21 has multiple grooves, including a first groove 21c and a second groove 21d that is shallower than the first groove 21c. In the first portion 21X of the substrate 21, some of the multiple optical fibers 12 are placed in the first groove 21c, and the optical fibers 12 not placed in the first groove 21c are placed in the second groove 21d. The exposed portion 21b is located further in the third direction D3 than the end of the optical fiber 12 placed in the first groove 21c. The exposed portion 21b is located below the lower end of the optical fiber 12 placed in the first groove 21c. As a result, the optical fiber 12 is in a floating state in the exposed portion 21b.

[0030] For example, among multiple optical fibers 12, the optical fiber 12 located in the second direction D2 is placed in the first groove 21c, and the optical fiber 12 located in the direction opposite to the second direction D2 is placed in the second groove 21d. In this embodiment, two of the four optical fibers 12 are placed in the first groove 21c, and the two optical fibers 12 not placed in the first groove 21c are placed in the second groove 21d.

[0031] When the substrate 21 is cut along a plane perpendicular to the first direction D1, the cross-section of the groove is V-shaped. The shape of this cross-section is constant along the first direction D1. For example, the angle formed by the sides of the first groove 21c when cut along a plane perpendicular to the first direction D1 is the same as the angle formed by the sides of the second groove 21d when cut along the same plane. This angle is, for example, 90°.

[0032] The substrate 21 has multiple grooves, for example, grooves on which optical fibers 12 can be placed and grooves on which optical fibers 12 cannot be placed. The grooves on which optical fibers 12 can be placed and the grooves on which optical fibers 12 cannot be placed are arranged alternately along the second direction D2. The substrate 21 has multiple first grooves 21c and multiple second grooves 21d. For example, the number of first grooves 21c is greater than the number of second grooves 21d. As an example, the number of first grooves 21c is 6 and the number of second grooves 21d is 2. For example, the multiple first grooves 21c include first grooves 21c on which optical fibers 12 can be placed and first grooves 21c on which optical fibers 12 cannot be placed.

[0033] The substrate 21 has a portion P1 in which first grooves 21c and second grooves 21d are arranged alternately along the second direction D2. The substrate 21 also has a portion P2 in which only first grooves 21c are arranged along the second direction D2. In portion P1, first grooves 21c and second grooves 21d are arranged in this order along the second direction D2. The portion P1 in which first grooves 21c and second grooves 21d are arranged alternately is located in the opposite direction to the second direction D2 than the portion P2 in which only first grooves 21c are arranged. Along the second direction D2, a portion P2 in which multiple portions of only first grooves 21c are arranged is adjacent to the portion P1 in which first grooves 21c and second grooves 21d are arranged alternately. In portion P1, first grooves 21c, second grooves 21d, first grooves 21c, and second grooves 21d that cannot be mounted on the optical fiber 12 are arranged in this order along the second direction D2. In section P2, the first grooves 21c on which the optical fiber 12 cannot be placed, the first grooves 21c on which the optical fiber 12 can be placed, the first grooves 21c on which the optical fiber 12 cannot be placed, and the first grooves 21c on which the optical fiber 12 can be placed are arranged in this order along the second direction D2.

[0034] The first lid 22 has a contact surface 22f into which the optical fiber 12 placed in the first groove 21c makes contact, and a third groove 22c that is recessed from the contact surface 22f and into which the optical fiber 12 placed in the second groove 21d enters. The contact surface 22f extends in the first direction D1 and the second direction D2. When cut along a plane perpendicular to the first direction D1, the cross-section of the third groove 22c is V-shaped. The shape of this cross-section is constant along the first direction D1. For example, the angle formed by the sides of the third groove 22c when cut along a plane perpendicular to the first direction D1 is smaller than the angle formed by the sides of the second groove 21d. This angle of the third groove 22c is, as an example, 60°. By having the third groove 22c, the height of the first lid 22 (the position of the top surface of the first lid 22) can be lowered compared to the case where the third groove 22c is not present.

[0035] Figure 5 is a side view showing the end face 21h of the substrate 21 and the end face 23b of the second lid 23. As shown in Figures 1 and 5, the substrate 21 has multiple grooves, including a first groove 21j and a second groove 21k that is shallower than the first groove 21j. In the second portion 21Y of the substrate 21, multiple optical fibers 12 are placed in the first groove 21j. In the second portion 21Y, no optical fibers 12 are placed in the second groove 21k.

[0036] As shown in Figures 2, 4, and 5, of the multiple optical fibers 12, the optical fiber 12c that is placed in the first groove 21c in the first portion 21X is bent in the opposite direction to the second direction D2 at the exposed portion 21b and is placed in the first groove 21j located one groove width in the opposite direction in the second portion 21Y. The optical fiber 12b that is placed in the second groove 21d in the first portion 21X is bent in the opposite direction at the exposed portion 21b and is placed in the first groove 21j located one groove width in the opposite direction in the second portion 21Y.

[0037] In the first section 21X, the positions of the multiple optical fibers 12 in the third direction D3 are different from each other. In the second section 21Y, the positions of the multiple optical fibers 12 in the third direction D3 are the same from each other. In the first section 21X, the multiple optical fibers 12 are not aligned in a straight line, whereas in the second section 21Y, the multiple optical fibers 12 are aligned in a straight line. The shape of the multiple grooves in the first section 21X is the same as the shape of the multiple grooves in the second section 21Y when viewed along the first direction D1. The shape of the multiple grooves in the first section 21X when viewed along the first direction D1 is the same as the shape of the multiple grooves in the second section 21Y when viewed along the first direction D1.

[0038] Figure 6 is a perspective view showing the substrate 21 before the exposed portion 21b is formed. As shown in Figures 4, 5, and 6, before the exposed portion 21b is formed, the first groove 21c of the first portion 21X is aligned in a straight line with the first groove 21j of the second portion 21Y, and the second groove 21d of the first portion 21X is aligned in a straight line with the second groove 21k of the second portion 21Y. Before the exposed portion 21b is formed, the first grooves 21c, 21j and the second grooves 21d, 21k are formed, extending in a straight line. Therefore, the grooves of the substrate 21 can be easily processed. By grinding or polishing the central portion of the substrate 21 in the first direction D1 to form the exposed portion 21b, the first groove and the second groove are separated, and the first groove 21c, the second groove 21d of the first portion 21X, and the first groove 21j, the second groove 21k of the second portion 21Y are formed.

[0039] Figure 7(1) is a perspective view showing the optical waveguide substrate 30. Figure 7(2) is a side view of the optical waveguide substrate 30 viewed along the direction opposite to the first direction D1. Figure 7(3) is a side view of the optical waveguide substrate 30 viewed along the first direction D1. As shown in Figures 1, 4 and 7, the optical waveguide substrate 30 has connecting surfaces 31b and 32b that are connected to the end face 21f of the substrate 21 and the end face 22b of the first cover 22.

[0040] For example, the optical waveguide substrate 30 includes a first optical waveguide substrate 31 and a second optical waveguide substrate 32. The first optical waveguide substrate 31 has a connection surface 31b that connects to the end face 22b of the first cover 22 and the optical fiber 12, and a connection surface 31c that connects to the fiber holder 40. The connection surface 31b extends in the second direction D2 and the third direction D3 at the end of the first optical waveguide substrate 31 in the first direction D1. The connection surface 31c extends in the second direction D2 and the third direction D3 at the end of the first optical waveguide substrate 31 in the direction opposite to the first direction D1.

[0041] The second optical waveguide substrate 32 has a connection surface 32b that connects to the end face 21f of the substrate 21 and the optical fiber 12, and a connection surface 32c that connects to the fiber holder 40. The connection surface 32b extends in the second direction D2 and the third direction D3 at the end of the second optical waveguide substrate 32 in the first direction D1. The connection surface 32c extends in the second direction D2 and the third direction D3 at the end of the second optical waveguide substrate 32 in the direction opposite to the first direction D1.

[0042] The first optical waveguide substrate 31 has an optical waveguide 33b. The optical waveguide 33b extends from the connection surface 31b of the first optical waveguide substrate 31 through the interior of the first optical waveguide substrate 31 to the connection surface 31c. The first optical waveguide substrate 31 has a plurality of optical waveguides 33b. The spacing of the plurality of optical waveguides 33b on the connection surface 31b matches the spacing of the plurality of optical fibers 12. The spacing of the plurality of optical waveguides 33b on the connection surface 31c matches the spacing of the cores 11b (see Figure 8), which will be described later, of the multicore fiber 11. Each of the plurality of cores 11b of the multicore fiber 11 is optically connected to each of the plurality of optical fibers 12 via the optical waveguide 33b.

[0043] The second optical waveguide substrate 32 has optical waveguides 33c. For example, the configuration of the second optical waveguide substrate 32 is the same as the configuration of the first optical waveguide substrate 31 described above. In this case, since the optical waveguide substrate 30 is manufactured from the first optical waveguide substrate 31 and the second optical waveguide substrate 32, which have identical configurations, the optical waveguide substrate 30 can be manufactured easily. The spacing of the multiple optical waveguides 33c on the connection surface 32b matches the spacing of the multiple optical fibers 12, and the spacing of the multiple optical waveguides 33c on the connection surface 32c matches the spacing of the cores 11b of the multicore fiber 11. Each of the multiple cores 11b of the multicore fiber 11 is optically connected to each of the multiple optical fibers 12 via the optical waveguide 33c.

[0044] FIG. 8 is a diagram showing an example of the multi-core fiber 11. FIG. 9 is a perspective view showing a fiber holder 40 that holds the multi-core fiber 11. As shown in FIGS. 7, 8, and 9, the arrangement of the cores 11b at the tip surface 11c of the multi-core fiber 11 coincides with the arrangement of the optical waveguides 33b, 33c at the connection surfaces 31c, 32c of the optical waveguide substrate 30. For example, at the tip surface 11c, the plurality of cores 11b are arranged such that the lines connecting the centers of adjacent cores form a rectangular shape. The plurality of cores 11b of the multi-core fiber 11 are arranged side by side along the third direction D3. As an example, the number of cores 11b in the multi-core fiber 11 is 4. At the tip surface 11c, the centers of the four cores 11b may be arranged to form a square shape. However, the number of cores 11b of the multi-core fiber 11 may be 8 and is not particularly limited. At the tip surface 11c, the number of cores 11b may be arranged in two rows, such as 4 cores in a two-row and two-stage arrangement, 6 cores in a three-row and two-stage arrangement, 8 cores in a four-row and two-stage arrangement, etc.

[0045] For example, the fiber holder 40 includes a holder base 41 having a groove 41b on which the multi-core fiber 11 is placed, and a lid 42 that covers the portion of the multi-core fiber 11 placed in the groove 41b. For example, each of the holder base 41 and the lid 42 extends in the first direction D1 and the second direction D2 and has a thickness in the third direction D3. The groove 41b extends along the first direction D1 on the upper end surface of the holder base 41.

[0046] The holder base 41 has a connection surface 41c that connects to the optical waveguide substrate 30. The connection surface 41c extends in the second direction D2 and the third direction D3 from the end of the holder base 41 in the first direction D1. The lid 42 has a connection surface 42c that connects to the optical waveguide substrate 30. The connection surface 42c extends in the second direction D2 and the third direction D3 from the end of the lid 42 in the first direction D1. The connection surface 41c of the holder base 41 and the connection surface 42c of the lid 42 are aligned along the third direction D3. By connecting the connection surface 41c of the holder base 41 and the connection surface 42c of the lid 42 to the connection surfaces 31c and 32c of the optical waveguide substrate 30, each core 11b of the multicore fiber 11 is optically connected to each optical waveguide 33b and 33c of the optical waveguide substrate 30.

[0047] The effects obtained from the optical connection structure 1 according to this embodiment will now be described. The optical connection structure 1 has an optical fiber array 20, which comprises a substrate 21 having a plurality of grooves, a first cover 22 that holds down a portion of a plurality of optical fibers 12 placed in the plurality of grooves, and a second cover 23 that holds down portions of the plurality of optical fibers 12 that are different from the first cover 22. The substrate 21 has a first portion 21X facing the first cover 22 and a second portion 21Y facing the second cover 23. In the first portion 21X, a portion of the plurality of optical fibers 12 is placed in the first groove 21c, and the optical fibers 12 not placed in the first groove 21c are placed in the second groove 21d, which is shallower than the first groove 21c. In the second portion 21Y, each of the plurality of optical fibers 12 is placed in the first groove 21j.

[0048] Even when the plurality of optical fibers 12 are not arranged along one direction in the first portion 21X of the substrate 21, the plurality of optical fibers 12 can be arranged along one direction (for example, the second direction D2) in the second portion 21Y of the substrate 21. In the first portion 21X, the plurality of optical fibers 12 are not arranged in a straight line because the optical fibers 12 are placed on both the first groove 21c and the second groove 21d, whereas in the second portion 21Y, the plurality of optical fibers 12 can be arranged in a straight line by placing the optical fibers 12 on the first groove 21j. By forming the first grooves 21c, 21j and the second grooves 21d, 21k in the substrate 21, the plurality of optical fibers 12 can be arranged in a straight line. Therefore, the processing of the optical connection structure 1 including the substrate 21 can be easily performed.

[0049] The shapes of the plurality of grooves in the first portion 21X may be the same as the shapes of the plurality of grooves in the second portion 21Y. In this case, the shapes of the plurality of grooves in the first portion 21X are the same as the shapes of the grooves in the second portion 21Y. Thereby, the processing of the substrate 21 having the first portion 21X and the second portion 21Y can be easily performed.

[0050] The substrate 21 may have a portion P1 in which the first grooves 21c and the second grooves 21d are alternately arranged along the second direction D2. In this case, compared with the case where the first groove 21c or the second groove 21d is continuously arranged along the second direction D2, the length of the substrate 21 in the second direction D2, which is the direction in which the grooves are arranged, can be reduced. Since the length of the optical connection structure 1 in the second direction D2 can be reduced, it contributes to miniaturization of the optical connection structure 1.

[0051] The first lid 22 may have a contact surface 22f with which the optical fiber 12 placed on the first groove 21c contacts, and a third groove 22c that is recessed from the contact surface 22f and into which the optical fiber 12 placed on the second groove 21d enters. In this case, the first lid 22 has the third groove 22c into which the optical fiber 12 placed in the second groove 22c shallower than the first groove 21c enters, and the optical fiber 12 enters the second groove 21d and the third groove 22c. Thereby, the length of the optical connection structure 1 in the third direction D3 can be reduced. Therefore, it contributes to miniaturization of the optical connection structure 1.

[0052] The substrate 21 may have an exposed portion 21b between the first portion 21X and the second portion 21Y, which is a portion in the third direction D3 where multiple optical fibers 12 are exposed. The exposed portion 21b may be located further in the third direction D3 than the ends of the optical fibers 12 in the third direction D3 that are placed in the first grooves 21c and 21j, which are deeper than the second grooves 21d and 21k. In this case, the exposed portion 21b is located further in the third direction D3 than the ends of the optical fibers 12 in the third direction D3 that are placed in the first grooves 21c and 21j, which are deeper than the second grooves 21d and 21k. Since the optical fibers 12 do not come into contact with the exposed portion 21b, wear of the optical fibers 12 due to contact can be reduced.

[0053] (Second Embodiment) The optical connection structure according to the second embodiment will be described with reference to Figures 10, 11, and 12. Some of the components of the optical connection structure according to the second embodiment are the same as some of the components of the optical connection structure 1 described above. In the following, explanations that overlap with the explanation of optical connection structure 1 will be omitted as appropriate, and the same reference numerals will be used.

[0054] The optical connection structure according to the second embodiment has an optical fiber array 20A in which the configuration of the plurality of grooves differs from that of the optical fiber array 20. The optical fiber array 20A comprises a substrate 21A having a plurality of grooves on which each of the plurality of optical fibers 12 is placed, a first cover 22A that holds down a portion of the plurality of optical fibers 12 placed in the plurality of grooves, and a second cover 23A that holds down portions of the plurality of optical fibers 12 that are different from the first cover 22A.

[0055] The substrate 21A has multiple grooves, including a first groove 21p and a second groove 21q that is shallower than the first groove 21p. In the first portion 21X of the substrate 21A, some of the optical fibers 12 are placed in the first groove 21p, and the optical fibers 12 not placed in the first groove 21p are placed in the second groove 21q. The angle formed by the sides of the second groove 21q when cut along a plane perpendicular to the first direction D1 is greater than the angle formed by the sides of the first groove 21p when cut along the same plane. For example, the angle of the second groove 21q is 90°, and the angle of the first groove 21p is 60°. The first lid 22A has a contact surface 22q into which the optical fibers 12 placed in the first groove 21p make contact, and a third groove 22p that is recessed from the contact surface 22q and into which the optical fibers 12 placed in the second groove 21q enter.

[0056] In the substrate 21A, grooves on which optical fibers 12 can be placed are arranged continuously along the second direction D2, and grooves on which optical fibers 12 cannot be placed are also arranged continuously along the second direction D2. The substrate 21A has a portion P3 on which first grooves 21p are arranged along the second direction D2, and a portion P4 on which second grooves 21q are arranged along the second direction D2. The substrate 21A has two portions P3, and portion P4 is located between the two portions P3. Along the second direction D2, a portion P3 on which only multiple first grooves 21p are arranged is adjacent to a portion P4 on which only multiple second grooves 21q are arranged. The number of first grooves 21p in portion P3 located in the second direction D2 of portion P4 is less than the number of first grooves 21p in portion P3 located in the opposite direction to the second direction D2 of portion P4. For example, the number of second grooves 21q in section P4 is 2, the number of first grooves 21p in section P3 located in the second direction D2 of section P4 is 2, and the number of first grooves 21p in section P3 located in the opposite direction to the second direction D2 of section P4 is 4.

[0057] In the second portion 21Y, the multiple grooves of the substrate 21A include a first groove 21r and a second groove 21s that is shallower than the first groove 21r. In the second portion 21Y of the substrate 21, multiple optical fibers 12 are placed in the first groove 21r. In the second portion 21Y, no optical fibers 12 are placed in the second groove 21s. Of the multiple optical fibers 12, the optical fiber 12b placed in the first groove 21p in the first portion 21X is bent in the opposite direction to the second direction D2 in the exposed portion 21b and is placed in the first groove 21r located four grooves away in the opposite direction in the second portion 21Y. The optical fiber 12c placed in the second groove 21q in the first portion 21X is bent in the opposite direction in the exposed portion 21b and is placed in the first groove 21r located four grooves away in the opposite direction in the second portion 21Y.

[0058] On the substrate 21A, the shapes of the multiple grooves in the first portion 21X when viewed along the first direction D1 are identical to the shapes of the multiple grooves in the second portion 21Y when viewed along the first direction D1. Therefore, before the exposed portion 21b is formed, the first groove 21p of the first portion 21X is aligned in a straight line with the first groove 21r of the second portion 21Y, and the second groove 21q of the first portion 21X is aligned in a straight line with the second groove 21s of the second portion 21Y. The central portion of the substrate 21A in the first direction D1 is polished to form the exposed portion 21b. As a result, the first and second grooves are separated, and the first groove 21p and second groove 21q of the first portion 21X, and the first groove 21r and second groove 21s of the second portion 21Y are formed.

[0059] In the optical connection structure according to the second embodiment, multiple optical fibers 12 can be aligned in a straight line by forming first grooves 21p, 21r and second grooves 21q, 21s in the substrate 21A. Therefore, the optical connection structure equipped with the substrate 21A can be easily processed. The angle formed by the sides of the second groove 21q when cut along a plane perpendicular to the first direction D1 is greater than the angle formed by the sides of the first groove 21p when cut along a plane perpendicular to the first direction D1. In this case, the angle of the second groove 21q, which is shallower than the first groove 21p, is greater than the angle of the first groove 21p. This reduces wear of the optical fiber 12 due to the corners of the second groove 21q contacting the outer surface of the optical fiber 12.

[0060] (Third Embodiment) The optical connection structure 51 according to the third embodiment will be described with reference to Figure 13. The optical connection structure 51 comprises an optical fiber array 20B different from the optical fiber array 20, an optical waveguide substrate 30, and a fiber holder 40. In the optical connection structure 1, the first optical waveguide substrate 31 and the second optical waveguide substrate 32 are arranged in this order along the third direction D3, and the cover 42 and the holder base 41 are arranged in this order along the third direction D3. In contrast, in the optical connection structure 51, the first optical waveguide substrate 31 and the second optical waveguide substrate 32 are arranged in this order along the third direction D3, and the cover 42 and the holder base 41 are arranged in this order along the third direction D3.

[0061] In the optical fiber array 20B, the first lid 22 and the substrate 21B are arranged in this order along the third direction D3, and the second lid 23B and the substrate 21B are arranged in this order along the third direction D3. The surface 21t located at the end of the substrate 21B in the first direction D1, and the surface 23t located at the end of the second lid 23B in the first direction D1, are inclined with respect to both the first direction D1 and the third direction D3. Surfaces 21t and 23t are surfaces that have been polished at an angle with respect to both the first direction D1 and the third direction D3.

[0062] Surfaces 21t and 23t are inclined surfaces that are tilted with respect to the first direction D1 and the third direction D3 so as they extend in the direction opposite to the third direction D3. In this case, it is possible to optically couple the multicore fiber 11 to the optical element located on surfaces 21t and 23t in the direction opposite to the third direction D3. Instead of surfaces 21t and 23t, inclined surfaces that are tilted with respect to the first direction D1 and the third direction D3 so as they extend in the third direction D3 may be formed. In this case, it is possible to optically couple the multicore fiber 11 to the optical element located on the inclined surface in the third direction D3.

[0063] Various embodiments of the optical connection structure relating to this disclosure have been described. However, the optical connection structure relating to this disclosure is not limited to the embodiments described above and may be further modified within the scope of the gist described in the claims. That is, the shape, size, material, number, and arrangement of each part of the optical connection structure can be appropriately changed within the scope of the gist described above.

[0064] For example, in the embodiment described above, an optical fiber array 20 was illustrated that includes a substrate 21 in which an exposed portion 21b is provided between the first portion 21X and the second portion 21Y. However, the configuration of the optical fiber array in the optical connection structure is not limited to the above example and can be changed as appropriate.

[0065] In the embodiments described above, an optical connection structure 1 having an optical fiber array 20, an optical waveguide substrate 30, and a fiber holder 40 was described. However, the optical connection structure does not have to have at least one of the optical waveguide substrate 30 and the fiber holder 40. For example, the optical connection structure may have only the optical fiber array 20, or only the optical fiber array 20 and the optical waveguide substrate 30.

[0066] 1…Optical connection structure 11…Multicore fiber 11b…Core 11c…Tip surface 12, 12b, 12c…Optical fiber 20, 20A, 20B…Optical fiber array 21, 21A, 21B…Substrate 21b…Exposed portion 21c…First groove 21d…Second groove 21f, 21h…End face 21j…First groove 21k…Second groove 21p…First groove 21q…Second groove 21r…First groove 21s…Second groove 21t…Surface 21X…First part 21Y…Second part 22, 22A…First cover 22b…End face 22c…Third groove 22d…End face 22f…Contact surface 22p…Third groove 22q…Contact surface 23, 23A, 23B…Second cover 23b, 23d... End surface 23t... Surface 30... Optical waveguide board 31... First optical waveguide board 31b, 31c... Connection surface 32... Second optical waveguide board 32b, 32c... Connection surface 33b, 33c... Optical waveguide 40... Fiber holder 41... Holder stand 41b... Groove 41c... Connection surface 42... Lid 42c...Connection surface 51...Optical connection structure P1, P2, P3, P4...part

Claims

1. An optical connection structure comprising: a substrate having a plurality of grooves on which each of a plurality of optical fibers can be placed, each of the plurality of grooves extending along a first direction and the plurality of grooves being arranged along a second direction intersecting the first direction; a first lid for holding down a portion of the plurality of optical fibers placed in the plurality of grooves; and a second lid positioned away from the first lid in the first direction for holding down portions of the plurality of optical fibers placed in the plurality of grooves that are different from the first lid, wherein the plurality of grooves include a first groove and a second groove that is shallower than the first groove; the substrate having a first portion facing the first lid along a third direction intersecting both the first and second directions, and a second portion facing the second lid along the third direction, wherein in the first portion, a portion of the plurality of optical fibers is placed in the first groove, and the optical fibers not placed in the first groove are placed in the second groove; and in the second portion, the plurality of optical fibers are placed in the first groove.

2. The optical connection structure according to claim 1, wherein the shape of the plurality of grooves in the first portion is the same as the shape of the plurality of grooves in the second portion.

3. The optical connection structure according to claim 1 or claim 2, wherein the cross-section of the groove when cut along a plane perpendicular to the first direction is V-shaped, and the angle formed by the sides of the second groove when cut along a plane perpendicular to the first direction is greater than the angle formed by the sides of the first groove when cut along a plane perpendicular to the first direction.

4. The optical connection structure according to any one of claims 1 to 3, wherein the substrate has portions in which the first grooves and the second grooves are arranged alternately along the second direction.

5. The optical connection structure according to any one of claims 1 to 4, wherein the first lid has a contact surface that contacts the optical fiber placed on the first groove, and a third groove that is recessed from the contact surface and into which the optical fiber placed on the second groove enters.

6. The optical connection structure according to any one of claims 1 to 5, wherein the substrate has an exposed portion between the first portion and the second portion, the exposed portion being located in the third direction further than the end of the optical fiber in the third direction placed on the first groove.

7. The optical connection structure according to any one of claims 1 to 6, wherein the surface of the substrate located at the end in the first direction and the surface of the second lid located at the end in the first direction are inclined with respect to both the first direction and the third direction.

8. The optical connection structure according to any one of claims 1 to 7, further comprising an optical waveguide substrate fixed to the end of the substrate in the direction opposite to the first direction and to the end of the first lid in the direction opposite to the first direction, and having a plurality of optical waveguides that optically connect to each of the plurality of optical fibers.

9. The optical connection structure according to claim 8, further comprising a fiber holder fixed to the opposite end of the optical waveguide substrate and holding a multicore fiber having a plurality of cores that optically connects to each of the plurality of optical waveguides.

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