Optical fiber array

Abstract

To suppress positional deviation in optical fiber without introducing a dedicated member for positioning and accurately arrange the optical fiber with comparatively less man-hours.SOLUTION: An optical fiber array 10 includes a first substrate 20 having a first surface 20a, a second substrate 30 having a second surface 30a and a plurality of optical fibers 40. The first surface has a plurality of first recessed parts 22 extending in a predetermined direction; a first projection 21 is provided between the adjacent first recessed parts; the second surface has a plurality of second projections 31 extending in the direction; a second recessed part 32 is provided between the adjacent second projections; the end part of the first projection facing the corresponding second recessed part is positioned in the second recessed part; the end part of the second projection facing the corresponding first recessed part is positioned in the first recessed part; and the optical fiber is held between the first projection and second recessed part facing each other and between the second projection and first recessed part facing each other.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an optical fiber array. [Background technology]

[0002] Conventionally, optical fiber arrays in which a plurality of optical fibers are arranged in multiple stages have been known. The optical fiber array is a connection component for coupling an optical fiber to an optical waveguide element in a state in which a plurality of optical fibers are arranged in a predetermined position. For example, Patent Document 1 describes an array type optical element in which a plurality of optical fibers are arranged in two stages. This array type optical element includes a first substrate having a plurality of first V grooves and a second substrate having a plurality of second V grooves. A first optical fiber is arranged in each of the first V grooves, and a second optical fiber is arranged in each of the second V grooves. The plurality of first V grooves and the plurality of second V grooves are formed to face each other. The first optical fiber and the second optical fiber are held by being sandwiched between the first substrate and the second substrate. An ultraviolet-curable adhesive is filled between the first substrate and the second substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5323800 Summary of the Invention

[0004] In the array type optical element of Patent Document 1, a pair of opposing V-grooves are formed in each of the first substrate and the second substrate in order to suppress misalignment of the second optical fiber in the lateral direction relative to the first optical fiber (in other words, the direction in which the first and second V-grooves are aligned). Cylindrical positioning members are disposed in the pair of V-grooves. Patent Document 1 describes that the positioning members support the first substrate and the second substrate, thereby suppressing misalignment of the second substrate relative to the first substrate in the lateral direction, and therefore it is possible to suppress misalignment of the second optical fiber in the lateral direction relative to the first optical fiber.

[0005] In addition, in this array type optical element, if the diameter of the positioning member is relatively large and a gap occurs between the opposing first and second optical fibers, a spacer is inserted into the gap. Patent Document 1 describes that by inserting a spacer, it is possible to suppress the second optical fiber from being misaligned in the vertical direction (in other words, the stacking direction of the first and second substrates) relative to the first optical fiber.

[0006] As described above, in the array-type optical element of Patent Document 1, without a positioning member, the second substrate could potentially shift in position endlessly in the horizontal direction relative to the first substrate, and without a spacer, the vertical positional accuracy of the second substrate relative to the first substrate could become unstable. Therefore, unless a dedicated positioning member (i.e., a positioning member and a spacer) is introduced, it is not possible to suppress the shifting of the optical fiber.

[0007] Furthermore, in order to align the optical fibers with precision when a dedicated positioning member is introduced, it is necessary to prepare a positioning member with a desired diameter, process the spacer to a desired thickness, etc., which increases the number of steps. Depending on the level of spacer processing technology, it may not be possible to align the optical fibers with precision.

[0008] The present invention has been made to address the above-mentioned problems. That is, one of the objects of the present invention is to provide an optical fiber array that can suppress the positional deviation of the optical fibers without introducing a dedicated positioning member and can arrange the optical fibers with high precision with a relatively small number of steps.

[0009] The optical fiber array (10) of the present invention is A first substrate (20) having a first surface (20a); a second substrate (30) having a second surface (30a) facing the first surface (20a); a plurality of optical fibers (40) sandwiched between the first substrate (20) and the second substrate (30); Equipped with. a plurality of first recesses (22) extending in a predetermined direction are provided at predetermined intervals (I) on the first surface (20a), and a first protrusion (21) extending in the predetermined direction is provided between two adjacent first recesses (22); a plurality of second protrusions (31) extending in the predetermined direction are provided at the predetermined intervals (I) on the second surface (30a), and a second recess (32) extending in the predetermined direction is provided between two adjacent second protrusions (31); Each of the first protrusions (21) faces a corresponding one of the second recesses (32), and at least a portion of each of the first protrusions (21) is located within the corresponding one of the second recesses (32); Each of the second protrusions (31) faces a corresponding one of the first recesses (22), and at least a portion of each of the second protrusions (31) is located within the corresponding one of the first recesses (22); Each of the optical fibers (40) is sandwiched between the opposing first convex portion (21) and the second concave portion (32), and between the opposing second convex portion (31) and the first concave portion (22).

[0010] According to the present invention, it is possible to suppress the misalignment of the optical fibers without introducing a dedicated member for positioning, and to arrange the optical fibers with high precision with a relatively small number of steps. [Brief description of the drawings]

[0011] [Figure 1] 1 is a plan view of an optical fiber array according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a side view of the optical fiber array. [Diagram 3] 3 is a cross-sectional view of the optical fiber array taken along line III-III in FIG. [Figure 4] FIG. 4 is a partial enlarged view of a region R in FIG. [Figure 5A] FIG. 11 is a diagram (part 1) showing another shape of the first recess. [Figure 5B] FIG. 2 is a diagram (part 2) showing another shape of the first recess. [Figure 5C] FIG. 3 is a diagram (part 3) showing another shape of the first recess. [Figure 6A] FIG. 11 is a diagram (part 1) showing another shape of the second protrusion. [Figure 6B] FIG. 2 is a diagram (part 2) showing another shape of the second protrusion. [Figure 6C] FIG. 3 is a diagram (part 3) showing another shape of the second protrusion. [Figure 6D] FIG. 4 is a diagram showing another shape of the second protrusion. [Figure 7] FIG. 2 is a partially enlarged view of a cross section of an optical fiber array according to a first modified example of the first embodiment. [Figure 8] FIG. 11 is a partially enlarged view of a cross section of an optical fiber array according to a second modified example of the first embodiment. [Figure 9] FIG. 5 is a partially enlarged view of a cross section of an optical fiber array according to a second embodiment of the present invention. [Figure 10] FIG. 11 is a partially enlarged view of a cross section of an optical fiber array according to a modified example of the second embodiment. [Figure 11] FIG. 11 is a partially enlarged view of a cross section of an optical fiber array according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] (First embodiment) Hereinafter, an optical fiber array 10 according to an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a plan view of the optical fiber array 10, and Fig. 2 is a side view of the optical fiber array. As shown in Figs. 1 and 2, the optical fiber array 10 includes a substrate 20 having a substantially rectangular parallelepiped shape, a substrate 30 having a substantially rectangular parallelepiped shape, and a plurality of optical fibers 40 sandwiched between the substrates 20 and 30.

[0013] The substrate 20 is made of glass and has a predetermined thickness in the z-axis direction. The short sides of the substrate 20 extend in the x-axis direction, and the long sides extend in the y-axis direction. As shown in FIG. 2, a step s is formed on the upper surface (surface in the +z-axis direction) of the substrate 20. The step s extends in the x-axis direction at a predetermined position on the long side of the substrate 20. A step surface 20e1 of the step s is located on the zx plane. The step s divides the upper surface of the substrate 20 into a surface 20a and a surface 20b. The surface 20a is located above the surface 20b by the height of the step s. As will be described later, the substrate 30 is disposed on the surface 20a, while the surface 20b is exposed to the outside. The substrate 20 and the surface 20a correspond to examples of the "first substrate" and the "first surface", respectively. The material of the substrate 20 is not limited to glass, and may be any material (e.g., ceramic) that can process the convex portion 21 and the concave portion 22 described later.

[0014] As shown in FIG. 1 and FIG. 2, the substrate 30 is made of glass and has a predetermined thickness in the z-axis direction. The long sides of the substrate 30 extend in the x-axis direction, and the short sides extend in the y-axis direction. The surface 30a (surface in the -z-axis direction) of the substrate 30 has substantially the same shape and size as the surface 20a of the substrate 20. The substrate 30 is disposed on the substrate 20 so that the entire surface 30a faces the surface 20a of the substrate 20. As a result, the end surface 30e1 of the substrate 30 in the -y-axis direction is flush with the step surface 20e1 of the substrate 20. In addition, the end surface 30e2 of the substrate 30 in the +y-axis direction is flush with the end surface 20e2 of the substrate 20. The substrate 30 and the surface 30a correspond to examples of the "second substrate" and the "second surface", respectively. The material of the substrate 30 is not limited to glass, and may be any material (e.g., ceramic) that can process the convex portion 31 and the concave portion 32 described later.

[0015] An array structure is formed on the surface 20a of the substrate 20 and the surface 30a of the substrate 30 to array a plurality of optical fibers 40 at predetermined positions. The optical fibers 40 arrayed (contained) in this array structure protrude from the step surface 20e1 of the substrate 20 and the end surface 30e1 of the substrate 30, and extend in the -y-axis direction on the surface 20b. A predetermined length of the coating material 40a is removed from a part of the optical fiber 40 in the +y-axis direction to expose the bare fiber (described later). The length of the coating material 40a to be removed is set sufficiently longer than the length of the array structure in the y-axis direction to ensure that the optical fiber 40 in the portion arranged in the array structure becomes a bare fiber. Therefore, the optical fiber 40 extending in the -y-axis direction on the surface 20b is covered with the coating material 40a from the middle. The step s of the substrate 20 is formed to have a height such that "the axis of the optical fiber 40 covered with the coating material 40a arranged on the surface 20b" is coaxial with "the axis of the optical fiber 40 housed in the recess 22." Hereinafter, this arrangement structure will be specifically described with reference to Figs. 3 and 4.

[0016] FIG. 3 is a cross-sectional view of the optical fiber array 10 taken along line III-III in FIG. 1. FIG. 4 is a partially enlarged view of region R in FIG. 3. As shown in FIG. 3, twelve recesses 22 extending in the y-axis direction are provided at a predetermined interval I on the surface 20a of the substrate 20. Eleven protrusions 21 extending in the y-axis direction are provided between two adjacent recesses 22. Each protrusion 21 and each recess 22 are continuously formed from the step surface 20e1 to the end surface 20e2 (see FIG. 2) of the substrate 20. Twelve protrusions 31 extending in the y-axis direction are provided at an interval I on the surface 30a of the substrate 30. Eleven recesses 32 extending in the y-axis direction are provided between two adjacent protrusions 31. Each protrusion 31 and each recess 32 are continuously formed from the end surface 30e1 to the end surface 30e2 (see FIG. 2) of the substrate 30. The convex portion 21 and the concave portion 22 are examples of a “first convex portion” and a “first concave portion”, respectively. The convex portion 31 and the concave portion 32 are examples of a “second convex portion” and a “second concave portion”, respectively.

[0017] As shown in FIG. 4, the top surface 21a of the protrusion 21 (in this embodiment, the surface in the +z-axis direction) is located above the surface 20a of the substrate 20, and the bottom surface 22a of the recess 22 (in this embodiment, the surface in the -z-axis direction) is located below the surface 20a. The protrusion 21 has a width (length in the x-axis direction) w1. The side walls of the protrusion 21 are parallel to each other and are located on the yz plane. The recess 22 has a width w3. The side walls of the recess 22 are parallel to each other and are located on the yz plane. The side walls of the protrusion 21 also function as side walls of the recess 22 adjacent to the protrusion 21. The sum of the width w1 and the width w3 is equal to the interval I (see FIG. 3). The top surface 21a and the bottom surface 22a correspond to examples of the "first top surface" and the "first bottom surface", respectively.

[0018] The top surface 21a includes a groove v1 having a V-shaped cross section. The groove v1 is configured with a pair of inclined surfaces whose width in the x-axis direction narrows as it becomes deeper in the z-axis direction. Similarly, the bottom surface 22a includes a groove v2 having a V-shaped cross section. The groove v2 is configured with a pair of inclined surfaces whose width in the x-axis direction narrows as it becomes deeper in the z-axis direction. In this embodiment, each of the pair of inclined surfaces is formed to form an angle of 90°.

[0019] On the other hand, the top surface 31a of the protrusion 31 (in this embodiment, the surface in the -z axis direction) is located below the surface 30a of the substrate 30, and the bottom surface 32a of the recess 32 (in this embodiment, the surface in the +z axis direction) is located above the surface 30a. The protrusion 31 has a width w2. The side walls of the protrusion 31 are parallel to each other and are located on the yz plane. The recess 32 has a width w4. The side walls of the recess 32 are parallel to each other and are located on the yz plane. The side walls of the protrusion 31 also function as the side walls of the recess 32 adjacent to the protrusion 31. The sum of the widths w2 and w4 is equal to the interval I (see FIG. 3) (i.e., w1+w3=w2+w4=I). In addition, in this embodiment, the relationships w1=w2 and w3=w4 are established, but as long as w1+w3=w2+w4 is established, w1≠w2 and w3≠w4 may also be established. The top surface 31a and the bottom surface 32a correspond to examples of a "second top surface" and a "second bottom surface", respectively.

[0020] The top surface 31a and the bottom surface 32a are both flat surfaces located on the xy plane.

[0021] Each convex portion 21 faces the corresponding concave portion 32. Also, the convex portion 21 and the concave portion 32 are formed such that w1 < w4 holds, whereby the end portions of each convex portion 21 are located within the corresponding concave portion 32. Similarly, each convex portion 31 faces the corresponding concave portion 22. Also, the convex portion 31 and the concave portion 22 are formed such that w2 < w3 holds, whereby the end portions of each convex portion 31 are located within the corresponding concave portion 22.

[0022] Between the 11 pairs of opposing convex portions 21 and concave portions 32, 11 optical fibers 40 are respectively sandwiched (see FIG. 3). Specifically, the optical fiber 40 is sandwiched by the groove v1 of the convex portion 21 and the bottom surface 32a of the concave portion 32. That is, the optical fiber 40 is in line contact with the pair of inclined surfaces constituting the groove v1 and the bottom surface 32a along the y-axis direction respectively (in other words, in a cross-sectional view, the optical fiber 40 is supported at three points by the groove v1 and the bottom surface 32a). The groove v1 functions as a positioning surface for positioning the optical fiber 40. The bottom surface 32a functions as a contact surface for realizing line contact with the optical fiber 40.

[0023] Similarly, between the 12 pairs of opposing convex portions 31 and concave portions 22, 12 optical fibers 40 are respectively sandwiched (see FIG. 3). Specifically, the optical fiber 40 is sandwiched by the top surface 31a of the convex portion 31 and the groove v2 of the concave portion 22. That is, the optical fiber 40 is in line contact with the top surface 31a along the y-axis direction and is in line contact with the pair of inclined surfaces constituting the groove v2 along the y-axis direction respectively (in other words, in a cross-sectional view, the optical fiber 40 is supported at three points by the top surface 31a and the groove v2). The top surface 31a functions as a contact surface for realizing line contact with the optical fiber 40. The groove v2 functions as a positioning surface for positioning the optical fiber 40.

[0024] The optical fiber 40 in the portion sandwiched between the opposing convex portion 21 and concave portion 32 and between the opposing convex portion 31 and concave portion 22 is a bare fiber from which the coating material 40a (see FIG. 2) has been removed, and its diameter is 0.125 mm in each case. The end face (not shown) of the optical fiber 40 in the +y-axis direction is flush with the end face 20e2 of the substrate 20 and the end face 30e2 of the substrate 30 (see FIG. 2). This is because, in the state where the optical fiber 40 is sandwiched between the substrate 20 and the substrate 30, the +y-axis direction ends of the substrate 20 and the substrate 30 are polished together with the optical fiber 40. In the present embodiment, the polishing angle (the angle formed with the xy plane) of the end face of the optical fiber 40 is 90°. Note that the +y-axis direction ends of the substrate 20 and the substrate 30 may be polished obliquely together with the optical fiber 40. In this case, it is desirable that the polishing angle be an acute angle (for example, 80° to 85°). Alternatively, the end face of the optical fiber 40 may be covered with an antireflection film. By obliquely polishing the end face of the optical fiber 40 or covering it with an antireflection film, multiple reflections of the signal light between the connected device can be suppressed, and as a result, a decrease in the optical characteristics of the signal light can be suppressed.

[0025] In a cross-sectional view, the convex portion 21, concave portion 22, convex portion 31, and concave portion 32 are processed so that the optical fiber 40 is supported at three points by the groove v1 and the bottom surface 32a, the optical fiber 40 is supported at three points by the top surface 31a and the groove v2, and a gap having a predetermined height is formed between the surface 20a of the substrate 20 and the surface 30a of the substrate 30. In the present embodiment, the depths of the concave portion 22 and the concave portion 32 are processed such that a relationship of d1 < d2 (strictly, 3d1 = d2) holds between the distance d1 from the center of the gap between the surface 20a and the surface 30a to the center of the optical fiber 40 accommodated in the concave portion 22 and the distance d2 from the center of the gap to the center of the optical fiber 40 accommodated in the concave portion 32. However, the magnitude relationship between the distance d1 and the distance d2 is not limited to this. The depths of the concave portion 22 and the concave portion 32 may be processed such that, for example, a relationship of d1 = d2 or d1 > d2 holds.

[0026] An adhesive A is filled between the surface 20a of the substrate 20, the surface 30a of the substrate 30, and the optical fiber 40. In this embodiment, a thermosetting resin is used as the adhesive A, but the adhesive is not limited to this, and for example, an ultraviolet curing resin may be used. Well-known resins may be used as the thermosetting resin or the ultraviolet curing resin. The optical fiber 40 and the substrate 30 are bonded to the substrate 20 by the adhesive A.

[0027] In this embodiment, the width w1 of the convex portion 21 is slightly shorter than the width w4 of the concave portion 32, and the width w2 of the convex portion 31 is slightly shorter than the width w3 of the concave portion 22. This is to prevent the occurrence of a situation in which the end of the convex portion 21 (or the convex portion 31) cannot be placed in the concave portion 32 (or the concave portion 22) due to a manufacturing error. Therefore, if no manufacturing error occurs, w1=w4 and w2=w3 may be satisfied. In addition, the number of optical fibers 40 to be clamped (i.e., the number of the convex portions 21, the concave portions 22, the convex portions 31, and the concave portions 32) may be appropriately changed depending on the type and structure of the device to which the optical fibers 40 are to be connected.

[0028] The optical fiber array 10 is manufactured as follows. That is, first, 23 optical fibers 40 are arranged in the groove v1 of the convex portion 21 and the groove v2 of the concave portion 22 of the substrate 20. At this time, the optical fibers 40 are held by a jig (not shown). Next, the substrate 30 is arranged on the substrate 20 so that the surface 30a of the substrate 30 faces the surface 20a of the substrate 20. More specifically, the substrate 30 is arranged on the substrate 20 so that the optical fibers 40 are sandwiched between the opposing convex portion 21 and the concave portion 32, and the optical fibers 40 are sandwiched between the opposing convex portion 31 and the concave portion 22. Next, the holding of the optical fibers 40 by the jig is released, and a thermosetting resin, which is a material of the adhesive A, is injected from the gap between the end surface 20e2 and the end surface 30e2 of the substrate 20. Next, the semi-finished product into which the thermosetting resin has been injected is heated at a predetermined temperature to harden the thermosetting resin, and the adhesive A is formed. The optical fibers 40 and the substrate 30 are bonded to the substrate 20 by the adhesive A, and the optical fiber array 10 is manufactured.

[0029] As described above, in the first embodiment, the end of each convex portion 21 is located in the corresponding concave portion 32, and the end of each convex portion 31 is located in the corresponding concave portion 22. Therefore, the amount of positional deviation of the substrate 30 in the lateral direction (x-axis direction) relative to the substrate 20 can be suppressed to at most "the amount of lateral movement of the convex portion 21 in the concave portion 32 (or the amount of lateral movement of the convex portion 31 in the concave portion 22)". Therefore, even without a positioning member, it is possible to suppress the substrate 30 from being endlessly misaligned in the lateral direction relative to the substrate 20. In addition, by sandwiching each optical fiber between the opposing convex portion 21 and the concave portion 32, and between the opposing convex portion 31 and the concave portion 22, the position of the substrate 30 in the vertical direction (z-axis direction) relative to the substrate 20 is uniquely determined. Therefore, even without a spacer, it is possible to maintain high positional accuracy of the substrate 30 in the vertical direction relative to the substrate 20. In addition, since a dedicated member for positioning is not required, it is possible to reduce the possibility that the number of steps related to the arrangement process of the optical fibers 40 will increase due to the preparation or processing of the dedicated member. As described above, according to the configuration of the first embodiment, it is possible to suppress misalignment of the optical fibers 40 without introducing a dedicated member for positioning, and to arrange the optical fibers 40 with high precision with a relatively small number of steps.

[0030] In particular, in the first embodiment, the grooves v1 and v2 functioning as positioning surfaces are provided on the same substrate (i.e., substrate 20). Therefore, even if substrate 30 is laterally displaced relative to substrate 20, the relative positional relationship in the lateral direction of the optical fibers 40 on groove v2 with respect to the optical fibers 40 on groove v1 is maintained. Therefore, according to the configuration of the first embodiment, it is possible to more appropriately suppress the displacement of the optical fibers 40 (particularly the displacement in the lateral direction), and to more accurately arrange the optical fibers 40 with a relatively small number of steps.

[0031] Furthermore, since no dedicated positioning components are required, the relative positional relationship (i.e., the array structure) of the optical fibers 40 can be changed relatively easily simply by adjusting the shapes of the convex portions 21 and concave portions 22 (and the convex portions 31 and concave portions 32) of the substrate 20 (and the substrate 30).

[0032] Furthermore, since an increase in the number of parts can be suppressed, an increase in manufacturing costs can be suppressed and the manufacturing process can be simplified.

[0033] Here, when grooves are provided not only in the convex portion 21 and the concave portion 22 of the substrate 20 but also in the convex portion 31 and the concave portion 32 of the substrate 30, in order to properly position the optical fiber 40, it is necessary to control the processing accuracy of the convex portion 21, the concave portion 22, the convex portion 31, and the concave portion 32 with an extremely high level so that the deepest parts of the opposing grooves are not laterally misaligned. In contrast, in the first embodiment, grooves are provided only in the convex portion 21 and the concave portion 22 of the substrate 20, and not in the convex portion 31 and the concave portion 32 of the substrate 30. Therefore, the required processing accuracy can be slightly relaxed compared to a configuration in which grooves are provided in all of these convex portions and concave portions. As a result, the manufacturing efficiency of the optical fiber array 10 can be improved.

[0034] In the first embodiment, the recess 22 of the substrate 20 is formed so that the bottom surface 22a includes a groove v2 having a V-shaped cross section, but the shape of the recess 22 is not limited to this. For example, as shown in FIG. 5A, the recess 22 may have a bottom surface 22b instead of the bottom surface 22a. The bottom surface 22b is configured so that the cross section is trapezoidal. Also, as shown in FIG. 5B, the recess 22 may have a bottom surface 22c instead of the bottom surface 22a. The bottom surface 22c is configured by connecting a pair of inclined surfaces by a curved surface. The bottom surfaces 22b and 22c include a pair of inclined surfaces for positioning the optical fiber 40. Alternatively, as shown in FIG. 5C, the recess 22 may have a bottom surface 22d instead of the bottom surface 22a. The bottom surface 22d includes a curved surface having substantially the same curvature as the outer periphery of the optical fiber 40. The optical fiber 40 is positioned by fitting a part of its outer periphery into the curved surface.

[0035] In the first embodiment, the convex portion 31 of the substrate 30 is formed so that its cross section has a rectangular shape and the top surface 31a is a flat surface that can be in line contact with the optical fiber 40 along the y-axis direction, but the shape of the convex portion 31 is not limited to this. For example, as shown in FIG. 6A, the convex portion 31 may have a top surface 31b instead of the top surface 31a. The convex portion 31 having the top surface 31b is configured to have a trapezoidal cross section. As shown in FIG. 6B, the convex portion 31 may have a top surface 31c instead of the top surface 31a. The top surface 31c is configured to have a cross section that is a downwardly convex curve. Furthermore, as shown in FIG. 6C, the convex portion 31 may have a top surface 31d instead of the top surface 31a. The top surface 31d is configured to have a wavy cross section. All of the top surfaces 31b to 31d are capable of being in line contact with the optical fiber 40 along the y-axis direction. 6D, the protrusion 31 may have a top surface 31e instead of the top surface 31a. The top surface 31e is a curved surface having substantially the same curvature as the outer periphery of the optical fiber 40. A part of the outer periphery of the optical fiber 40 fits into the curved surface, so that the entire top surface 31e comes into contact with (a part of) the outer periphery of the optical fiber 40.

[0036] (Variation 1) Next, an optical fiber array according to Modification 1 of the first embodiment will be described. This optical fiber array differs from the optical fiber array 10 in the arrangement structure of the optical fibers 40. In the following, the same members or structures as those in the first embodiment are given the same reference numerals, and detailed description thereof will be omitted. This also applies to the other embodiments and modifications.

[0037] Fig. 7 is a partially enlarged view (corresponding to Fig. 4) of a cross section of the optical fiber array of the first modification. As shown in Fig. 7, this optical fiber array includes a substrate 120 and a substrate 130A. Substrate 120 differs from substrate 20 in that a convex portion 121 is provided on surface 120a instead of convex portion 21. Substrate 130A also differs from substrate 30 in that a concave portion 132 is provided on surface 130a1 instead of concave portion 32.

[0038] The top surface 121a (first top surface) of the convex portion 121 (first convex portion) is a flat surface located on the xy plane. In contrast, the bottom surface 132a (second bottom surface) of the concave portion 132 (second concave portion) includes a groove v3 having a V-shaped cross section. Each convex portion 121 faces the corresponding concave portion 132. An end of each convex portion 121 is located in the corresponding concave portion 132. A corresponding optical fiber 40 is sandwiched between the opposing convex portion 121 and concave portion 132. That is, in a cross-sectional view, the optical fiber 40 is supported at three points by the top surface 121a and the groove v3. The top surface 121a functions as a contact surface for realizing line contact with the optical fiber 40. The groove v3 functions as a positioning surface for positioning the optical fiber 40.

[0039] The first modification can also achieve the same effects as those of the first embodiment. However, in the first modification, the grooves v2 and v3 functioning as positioning surfaces are provided on separate substrates (i.e., substrate 20 and substrate 30). For this reason, if the substrate 130A is laterally displaced relative to the substrate 120, the optical fiber 40 on the groove v3 is also laterally displaced relative to the optical fiber 40 on the groove v2. The amount of displacement is at most within the range of "the amount of lateral movement of the convex portion 121 (or the convex portion 31) in the concave portion 132 (or the concave portion 22)". Therefore, the optical fiber array of the first modification is preferably used for coupling with an optical element that tolerates this degree of displacement.

[0040] (Variation 2) Next, an optical fiber array according to Modification 2 of the first embodiment will be described. This optical fiber array differs from the optical fiber array 10 in the arrangement structure of the optical fibers 40.

[0041] Fig. 8 is a partially enlarged view (corresponding to Fig. 4) of a cross section of the optical fiber array of Modification 2. As shown in Fig. 8, this optical fiber array includes a substrate 20 and a substrate 130B. Substrate 130B differs from substrate 30 in that a convex portion 131 is provided on surface 130a2 instead of convex portion 31, and a concave portion 132 is provided instead of concave portion 32.

[0042] The top surface 131a (second top surface) of the convex portion 131 (second convex portion) includes a groove v4 having a V-shaped cross section. The recess 132 has the same shape as the recess 132 of the first modification. Each convex portion 21 faces the corresponding recess 132. An end of each convex portion 21 is located in the corresponding recess 132. The optical fiber 40 is sandwiched between the opposing convex portion 21 and recess 132. That is, in a cross-sectional view, the optical fiber 40 is supported at four points by the groove v1 and the groove v3. The groove v1 and the groove v3 both function as positioning surfaces for positioning the optical fiber 40. Similarly, each convex portion 131 faces the corresponding recess 22. An end of each convex portion 131 is located in the corresponding recess 22. The optical fiber 40 is sandwiched between the opposing convex portion 131 and recess 22. That is, in a cross-sectional view, the optical fiber 40 is supported at four points by the groove v4 and the groove v2. Both the groove v4 and the groove v2 function as positioning surfaces for positioning the optical fiber 40.

[0043] Modification 2 can also achieve the same effects as those of the first embodiment. Furthermore, in Modification 2, grooves functioning as positioning surfaces are provided not only in the convex portion 21 and the concave portion 22 of the substrate 20, but also in the convex portion 131 and the concave portion 132 of the substrate 130B. This makes it possible to suppress lateral positional deviation of the substrate 130B itself.

[0044] Second embodiment Next, an optical fiber array according to a second embodiment of the present invention will be described. This optical fiber array differs from the optical fiber array 10 in the arrangement structure of the optical fibers 40.

[0045] Fig. 9 is a partially enlarged view (corresponding to Fig. 4) of a cross section of the optical fiber array of the second embodiment. As shown in Fig. 9, this optical fiber array includes a substrate 220 and a substrate 230. The substrate 220 differs from the substrate 20 in that a convex portion 221 is provided on the surface 220a instead of the convex portion 21, and a concave portion 222 is provided instead of the concave portion 22. The substrate 230 differs from the substrate 30 in that a convex portion 231 is provided on the surface 230a instead of the convex portion 31, and a concave portion 232 is provided instead of the concave portion 32.

[0046] The top surface 221a (first top surface) of the convex portion 221 (first convex portion) is a flat surface located on the xy plane. The convex portion 221 has a protruding portion 221p (first protruding portion). The protruding portion 221p protrudes from an end portion on the +x-axis direction side of the top surface 221a into the corresponding concave portion 232 (second concave portion). The protruding portion 221p has a rectangular cross section and extends in the y-axis direction from one end of the convex portion 221 to the other end. The side surface 221pa (surface on the -x-axis direction side) of the protruding portion 221p is perpendicular to the top surface 221a. In contrast, the depth of the concave portion 232 (the distance from the center of the gap between the surface 220a and the surface 230a to the bottom surface 232a) is shorter than the depth of the concave portion 32 (see FIG. 4). In addition, the side wall 232b on the -x-axis direction side of the concave portion 232 is inclined with respect to the yz plane.

[0047] Each of the convex portions 221 faces a corresponding concave portion 232. Moreover, each of the protruding portions 221p is located in a corresponding concave portion 232. A corresponding optical fiber 40 is sandwiched between the opposing convex portion 221 and concave portion 232. Specifically, the optical fiber 40 is in line contact with the top surface 221a of the convex portion 221, the side surface 221pa of the protruding portion 221p, and the side wall 232b (i.e., the side wall facing the side surface 221pa) of the concave portion 232 along the y-axis direction (in other words, in a cross-sectional view, the optical fiber 40 is supported at three points by the top surface 221a, the side surface 221pa, and the side wall 232b).

[0048] On the other hand, the convex portion 231 (second convex portion) has a protruding portion 231p (second protruding portion). The protruding portion 231p protrudes from the end portion on the -x-axis direction side of the top surface 231a (second top surface) into the corresponding concave portion 222 (first concave portion). The cross section of the protruding portion 231p is in the shape of a right-angled triangle, and extends in the y-axis direction from one end of the convex portion 231 to the other end. The width of the protruding portion 231p narrows downward. A side surface 231pa (surface on the +x-axis direction side) of the protruding portion 231p intersects with the top surface 231a at an obtuse angle. In contrast, the bottom surface 222a (first bottom surface) of the concave portion 222 is a flat surface located on the xy plane.

[0049] Each of the projections 231 faces a corresponding recess 222. Each of the projections 231p is located in a corresponding recess 222. The corresponding optical fiber 40 is sandwiched between the projections 231 and recesses 222 that face each other. Specifically, the optical fiber 40 is in line contact with the side surface 231pa of the projection 231p, the bottom surface 222a of the recess 222, and the side wall 222b (i.e., the side wall facing the side surface 231pa) of the recess 222 on the +x-axis direction side along the y-axis direction (in other words, in a cross-sectional view, the optical fiber 40 is supported at three points by the side surface 231pa, the bottom surface 222a, and the side wall 222b). The width of the recess 222 is shorter than the width of the projection 221.

[0050] In the first embodiment, the optical fiber 40 is sandwiched between "the top surface 21a of the convex portion 21 and the bottom surface 32a of the concave portion 32 facing each other" and "between the top surface 31a of the convex portion 31 and the bottom surface 22a of the concave portion 22 facing each other". In contrast, in the second embodiment, the optical fiber 40 is sandwiched between "the top surface of the convex portion, the side surface of the protruding portion of the convex portion, and the side wall of the concave portion facing the convex portion", or "between the side surface of the protruding portion of the convex portion, the bottom surface of the concave portion facing the convex portion, and the side wall of the concave portion". Of the three surfaces with which the optical fiber 40 comes into contact, one surface is inclined with respect to the yz plane. As a result, even if no positioning surface is formed on the convex portion or the concave portion, the position of the optical fiber 40 is uniquely determined. Therefore, the second embodiment can also achieve the same effect as the first embodiment. The protruding portion 231p may be formed to have the same shape as the protruding portion 221p. In this case, it is desirable that the recess 222 is formed so that its side wall 222b is inclined in the same direction as the side wall 232b of the recess 232. Moreover, the protrusions 221p and 231p do not have to be formed continuously from one end to the other end of the convex portions 221 and 231. That is, a plurality of divided protrusions 221p and 231p may be provided at intervals in the y-axis direction. This also applies to modified examples described later.

[0051] (Modification) Next, a description will be given of an optical fiber array according to a modification of the second embodiment. This optical fiber array differs from the optical fiber array of the second embodiment in the arrangement structure of the optical fibers 40.

[0052] Fig. 10 is a partially enlarged view (corresponding to Fig. 9) of a cross section of an optical fiber array of a modified example. As shown in Fig. 10, this optical fiber array includes a substrate 320 and a substrate 330. Substrate 320 differs from substrate 220 in that a convex portion 321 is provided on surface 320a instead of convex portion 221. Substrate 330 differs from substrate 230 in that a convex portion 331 is provided on surface 330a instead of convex portion 231, and a concave portion 332 is provided instead of concave portion 232.

[0053] The convex portion 321 (first convex portion) has a protruding portion 321p. The protruding portion 321p protrudes from an end portion on the +x-axis direction side of the top surface 321a (first top surface) into the corresponding concave portion 332. The protruding portion 321p has a cross section in the shape of a right-angled triangle and extends in the y-axis direction from one end of the convex portion 321 to the other end. A side surface 321pa of the protruding portion 321p intersects with the top surface 321a at an obtuse angle. In contrast, the concave portion 332 (second concave portion) has substantially the same structure as the concave portion 232 of the second embodiment, except that a side wall 332b on the -x-axis direction side is located on the yz plane.

[0054] The optical fiber 40 is sandwiched between the opposing protrusions 321 and recesses 332. Specifically, the optical fiber 40 is in line contact with the side surface 321pa of the protrusion 321p, the bottom surface 332a (second bottom surface) of the recess 332, and the side wall 332b (i.e., the side wall facing the side surface 321pa) of the recess 332 along the y-axis direction (in other words, in a cross-sectional view, the optical fiber 40 is supported at three points by the side surface 321pa, the bottom surface 332a, and the side wall 332b).

[0055] On the other hand, the protrusion 331 has a protrusion 331p having the same shape as the protrusion 231p of the second embodiment. The corresponding optical fiber 40 is sandwiched between the opposing protrusion 331 and recess 222. Specifically, the optical fiber 40 is in line contact with a side surface 331pa of the protrusion 331p, a bottom surface 222a of the recess 222, and a side wall 222b of the recess 222 along the y-axis direction (in other words, in a cross-sectional view, the optical fiber 40 is supported at three points by the side surface 331pa, the bottom surface 222a, and the side wall 222b).

[0056] This configuration also provides the same advantageous effects as the second embodiment.

[0057] Third embodiment Next, an optical fiber array according to a third embodiment of the present invention will be described. The optical fiber array according to the second embodiment differs from the optical fiber array 10 in the arrangement structure of the optical fibers 40.

[0058] Fig. 11 is a partially enlarged view (corresponding to Fig. 4) of a cross section of the optical fiber array of the third embodiment. As shown in Fig. 11, this optical fiber array includes a substrate 420 and a substrate 430. The substrate 420 differs from the substrate 20 in that a convex portion 421 is provided on the surface 420a instead of the convex portion 21. The substrate 430 differs from the substrate 30 in that a concave portion 432 is provided on the surface 430a instead of the concave portion 32.

[0059] A step s1 is provided on the top surface 421a (first top surface) of each of the eleven convex portions 421 (first convex portions), thereby dividing the top surface 421a into two divided top surfaces 421a1 and 421a2 (first divided top surfaces). In contrast, a step s2 is provided on the bottom surface 432a (second bottom surface) of each of the corresponding eleven concave portions 432 (second concave portions) in the same number as the step (i.e., step s1) provided on the top surface 421a, thereby dividing the bottom surface 432a into two divided bottom surfaces 432a1 and 432a2 (second divided bottom surfaces). The divided bottom surfaces 432a1 and 432a2 each include a groove v5 and a groove v6 having a V-shaped cross section.

[0060] Each divided top surface 421a1 and 421a2 faces the corresponding divided bottom surface 432a1 and 432a2. The portion of each convex portion 421 having the divided top surface 421a2 is defined as a "partial convex portion", and the portion of each concave portion 432 having the divided bottom surface 432a2 is defined as a "partial concave portion". In this case, each partial convex portion faces the corresponding partial concave portion. Also, the end of each partial convex portion is located within the corresponding partial concave portion.

[0061] Between the eleven pairs of opposing split top surface 421a1 and split bottom surface 432a1, the corresponding optical fiber 40 is sandwiched. That is, in a cross-sectional view, the optical fiber 40 is supported at three points by the split top surface 421a1 and the groove v5. Similarly, between the eleven pairs of opposing split top surface 421a2 and split bottom surface 432a2 (in other words, between opposing partial convex portions and partial concave portions), the corresponding optical fiber 40 is sandwiched. That is, in a cross-sectional view, the optical fiber 40 is supported at three points by the split top surface 421a2 and the groove v6. The split top surfaces 421a1 and 421a2 function as contact surfaces for realizing line contact with the optical fiber 40. The groove v5 and the groove v6 function as positioning surfaces for positioning the optical fiber 40.

[0062] In the third embodiment, one step s1 is provided on the top surface 421a of the convex portion 421, and one step s2 is provided on the bottom surface 432a of the concave portion 432. With this configuration, an optical fiber array arranged in three stages can be realized. However, the optical fibers 40 are not limited to being arranged in all stages. For example, the optical fiber array of the third embodiment may be arranged to be arranged only in the first and third stages. The number of steps is not limited to this. In general, when k steps (k: natural number) are provided, an optical fiber array arranged in k+2 stages can be realized. In addition, the grooves v5 and v6 may be provided on the divided top surfaces 421a1 and 421a2 instead of being provided on the divided bottom surfaces 432a1 and 432a2, or may be provided on all of these divided top surfaces and divided bottom surfaces. Furthermore, steps may be provided on each convex portion 31 (second convex portion) of the substrate 430 and each concave portion 22 (first concave portion) of the substrate 420. In this case, the top surface 31a of the protrusion 31 is divided into a plurality of divided top surfaces (second divided top surfaces), and the bottom surface 22a of the recess 22 is divided into a plurality of divided bottom surfaces (first divided bottom surfaces). Furthermore, the steps may be provided in all of the protrusions 421, recesses 432, protrusions 31, and recesses 22.

[0063] The optical fiber array according to the embodiment and the modified examples have been described above, but the present invention is not limited to the above-mentioned embodiment and modified examples, and various modifications are possible without departing from the object of the present invention.

[0064] The optical fiber array is not limited to the configurations shown in the embodiments and modifications. For example, the end faces 20e2 and 30e2 (see FIG. 2) may be processed into a lens array.

[0065] Furthermore, when the optical fiber 40 is sandwiched between the opposing convex and concave portions, the line contact may be discontinuous.

[0066] Furthermore, one or more substrates may be stacked on the lower surface of substrate 20 and / or the upper surface of substrate 30 (see FIG. 2). In this case, the above-mentioned arrangement structure of optical fibers 40 may be formed between any two paired substrates. [Explanation of symbols]

[0067] 10: optical fiber array, 20: substrate, 20a: surface, 21: convex portion, 22: concave portion, 30: substrate, 30a: surface, 31: convex portion, 32: concave portion, 40: optical fiber

Claims

1. a first substrate having a first surface; a second substrate having a second surface opposite to the first surface; a plurality of optical fibers sandwiched between the first substrate and the second substrate; Equipped with a plurality of first recesses extending in a predetermined direction are provided at predetermined intervals on the first surface, and a first protrusion extending in the predetermined direction is provided between two adjacent first recesses; a plurality of second protrusions extending in the predetermined direction are provided at the predetermined intervals on the second surface, and a second recess extending in the predetermined direction is provided between two adjacent second protrusions; Each of the first projections faces a corresponding one of the second recesses, and at least a portion of each of the first projections is located within the corresponding one of the second recesses; Each of the second protrusions faces a corresponding one of the first recesses, and at least a portion of each of the second protrusions is located within the corresponding one of the first recesses; Each of the optical fibers is sandwiched between the first convex portion and the second concave portion, and between the second convex portion and the first concave portion, which face each other. Optical fiber array.

2. 2. The optical fiber array according to claim 1, At least one of a first top surface which is a top surface of each of the first convex portions and a second bottom surface which is a bottom surface of the corresponding second concave portion includes a positioning surface for positioning the corresponding optical fiber, At least one of a second top surface which is a top surface of each of the second convex portions and a first bottom surface which is a bottom surface of the corresponding first concave portion includes the positioning surface. Optical fiber array.

3. 3. The optical fiber array according to claim 2, one of the first top surface and the corresponding second bottom surface includes the positioning surface, and the other of the first top surface and the corresponding second bottom surface includes a contact surface capable of making line contact with the corresponding optical fiber in at least a part of the predetermined direction; One of the second top surface and the corresponding first bottom surface includes the positioning surface, and the other of the second top surface and the corresponding first bottom surface includes the contact surface. Optical fiber array.

4. 3. The optical fiber array according to claim 2, The positioning surface is a surface including a pair of inclined surfaces whose width in the horizontal direction narrows as the depth in the vertical direction increases, or a curved surface having substantially the same curvature as the outer periphery of the optical fiber. Optical fiber array.

5. 4. The optical fiber array according to claim 3, The positioning surface is a surface including a pair of inclined surfaces whose width in the horizontal direction narrows as the depth in the vertical direction increases, or a curved surface having substantially the same curvature as the outer periphery of the optical fiber. Optical fiber array.

6. 2. The optical fiber array according to claim 1, At least one of the first convex portion and the second convex portion has a first protruding portion protruding from a part of the first top surface in a lateral direction into the corresponding second concave portion, or a second protruding portion protruding from a part of the second top surface in a lateral direction into the corresponding first concave portion, When each of the first convex portions has the first protruding portion, the corresponding optical fiber is in contact with a side surface of the first protruding portion, When each of the second convex portions has the second protruding portion, the corresponding optical fiber is in contact with a side surface of the second protruding portion. Optical fiber array.

7. The optical fiber array according to any one of claims 1 to 6, a first top surface, which is a top surface of each of the first convex portions, is provided with one or more steps, thereby dividing the first top surface into a plurality of first divided top surfaces; a second bottom surface, which is a bottom surface of the corresponding second concave portion, is provided with steps the same number as the steps, thereby dividing the second bottom surface into a plurality of second divided bottom surfaces; Each of the first divided top surfaces faces a corresponding one of the second divided bottom surfaces, Among the plurality of pairs of opposing first divided top surfaces and second divided bottom surfaces, at least one pair of opposing first divided top surfaces and second divided bottom surfaces has a corresponding optical fiber sandwiched therebetween. Optical fiber array.

8. 8. The optical fiber array according to claim 7, a second top surface which is a top surface of each of the second convex portions is provided with one or more steps, thereby dividing the second top surface into a plurality of second divided top surfaces; a first bottom surface which is a bottom surface of the corresponding first concave portion is provided with steps the same number as the steps, thereby dividing the first bottom surface into a plurality of first divided bottom surfaces; Each of the second divided top surfaces faces a corresponding one of the first divided bottom surfaces, Among the plurality of pairs of opposing second divided top surfaces and first divided bottom surfaces, at least one pair of opposing second divided top surfaces and first divided bottom surfaces has a corresponding optical fiber sandwiched therebetween. Optical fiber array.

9. The optical fiber array according to any one of claims 1 to 6, a second top surface which is a top surface of each of the second convex portions is provided with one or more steps, thereby dividing the second top surface into a plurality of second divided top surfaces; a first bottom surface which is a bottom surface of the corresponding first concave portion is provided with steps the same number as the steps, thereby dividing the first bottom surface into a plurality of first divided bottom surfaces; Each of the second divided top surfaces faces a corresponding one of the first divided bottom surfaces, Among the plurality of pairs of opposing second divided top surfaces and first divided bottom surfaces, at least one pair of opposing second divided top surfaces and first divided bottom surfaces has a corresponding optical fiber sandwiched therebetween. Optical fiber array.

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