JP2013195562A - Optical fiber branching device and method of manufacturing optical fiber branching device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber branching device which allows end parts of a plurality of single core optical fibers to be easily inserted to a hole of a ferrule and allows the end parts of the plurality of single core optical fibers to be arranged with high accuracy.SOLUTION: The optical fiber branching device includes a ferrule 20A. An optical fiber insertion hole 22 of the ferrule 20A pierces the ferrule 20A in a prescribed direction and includes a first area 22a, a second area 22b, and a third area 22c arranged in this order from one end side in the prescribed direction. The first area 22a holds end parts of a plurality of single core optical fibers in accordance with core arrangement of a multi-core optical fiber. An inside diameter of the third area 22c is larger than that of the first area 22a. An inside diameter of the second area 22b is increased from the side of the first area 22a toward the third area 22c, and an angle formed between an inside surface in the second area 22b and the prescribed direction is 10° or less.

Description

  The present invention relates to an optical fiber branch device and a method for manufacturing the optical fiber branch device.

  Patent Document 1 describes an optical coupler for a multi-core optical fiber. In Patent Document 1, a multi-core optical fiber including one core and six cores arranged at intervals of 60 ° around the one core and seven single-core optical fibers are optically coupled to each other. As a method, first, a V-groove having an angle of 60 ° is prepared, ten single-core optical fibers are arranged in the V-groove, and seven single-core optical fibers located near the center of the ten single-core optical fibers are arranged. Optical coupling between a fiber and the multi-core optical fiber is described.

  Patent Document 2 discloses a connector structure including a ferrule that holds a multi-core optical fiber. In this connector structure, the ferrule that holds the multi-core optical fiber is supported so as to be adjustable in rotation.

JP 58-14108 A US Patent Application Publication No. 2011/0229085

  In general, optical coupling between an optical fiber and another optical component (such as an optical fiber or a light emitting element) is performed by abutting a ferrule attached to the tip of the optical fiber. Even when each optical axis of an optical component having a plurality of optical axes (for example, a multi-core optical fiber having a plurality of cores) and a plurality of single-core optical fibers are mutually coupled, It is desirable to abut the optical part with the ferrule attached with the tip portion together.

  However, the diameter of the uncoated single-core optical fiber is usually about 40 μm to 50 μm and extremely thin. Therefore, when a plurality of single core optical fibers are inserted into the ferrule hole, the single core optical fiber is weak in elasticity, so that it is difficult to insert, and there is a high possibility of disconnection during the insertion process. It is also conceivable to simply increase the inner diameter of the ferrule hole in order to alleviate such insertion difficulty. However, if the inner diameter of the ferrule hole is large, a large gap is generated between the plurality of single-core optical fibers and the inner surface of the hole. Therefore, the plurality of single-core optical fibers are easily arranged with a deviation from the central axis of the ferrule. The optical loss between each optical axis of the optical component and the plurality of single core optical fibers becomes large.

  The present invention has been made in view of such problems, and can easily insert the ends of a plurality of single-core optical fibers into the hole of the ferrule, and the ends of the plurality of single-core optical fibers. It is an object to provide an optical fiber branch device capable of suppressing optical loss between each optical axis of an optical component and a plurality of single core optical fibers, and a method for manufacturing the optical fiber branch device. To do.

  In order to solve the above-described problems, an optical fiber branch device according to the present invention is an optical fiber branch device for optically coupling a plurality of single-core optical fibers to an optical component having a plurality of optical axes. A ferrule having an optical fiber insertion hole that accommodates an end portion of the single core optical fiber, the optical fiber insertion hole passes through the ferrule in a predetermined direction, and the end surfaces of the plurality of single core optical fibers are formed of ferrules in the predetermined direction. The optical fiber insertion hole is exposed from one end side, and the optical fiber insertion hole includes a first region, a second region, and a third region arranged in a predetermined direction in order from the one end side, and the first region includes end portions of a plurality of single core optical fibers. Holding according to the arrangement of the plurality of optical axes of the optical component, the inner surface of the first region is along a predetermined direction, the inner diameter of the third region is larger than the inner diameter of the first region, The inner surface of the three regions is along a predetermined direction, the inner diameter of the second region is expanded from the first region side toward the third region side, and the angle formed by the inner surface of the second region and the predetermined direction is 10 ° or less. It is characterized by being.

  In this optical fiber branching device, the optical fiber insertion hole of the ferrule includes a first region, a second region, and a third region. And the edge part of a some single core optical fiber can be collectively inserted from the 3rd area | region where an internal diameter is comparatively large. Thereby, it becomes easy to insert a plurality of single core optical fibers into the optical fiber insertion hole, and disconnection in the process of insertion can be reduced. The end portions of the plurality of single-core optical fibers thus inserted in the third region then pass through the second region. Since the inner diameter of the second region is expanded from the first region side toward the third region side, the end portions of the plurality of single core optical fibers are guided to the inner surface of the second region and gradually become thinner. Continue on. As a result, when the ends of the plurality of single core optical fibers reach the third region, the ends of the plurality of single core optical fibers are accommodated in the relatively narrow holes. The end portions are aligned according to an arrangement of a plurality of optical axes of the optical component (for example, a core arrangement of a multicore optical fiber). Subsequently, the plurality of single core optical fibers are further inserted into the optical fiber insertion hole. Since the inner surface of the first region is along a predetermined direction, the optical axis direction of the end portions of the plurality of single-core optical fibers has a shape (preferably parallel) along the predetermined direction in the first region. Thus, the end portions of the plurality of single core optical fibers are accurately arranged, and light loss between each optical axis of the optical component and the plurality of single core optical fibers is suppressed.

  Thus, according to the optical fiber branching device, the ends of the plurality of single core optical fibers can be easily inserted into the hole of the ferrule, and the ends of the plurality of single core optical fibers are arranged with high accuracy. Thus, it is possible to suppress optical loss between each optical axis of the optical component and the plurality of single core optical fibers.

  Further, in the optical fiber branching device, the difference between the outer diameter of the optical fiber bundle formed by bundling the ends of a plurality of single core optical fibers and the inner diameter of the optical fiber insertion hole is larger than 0 μm and smaller than 3 μm in the first region. It is good also as a feature.

  Further, in the first region, the end portion of the plurality of single core optical fibers is arranged so as to include one or a plurality of unit structures in which the three single core optical fibers are in contact with each other in the first region. It may be a feature.

  The optical fiber branching device may be characterized in that the length of the first region in a predetermined direction is not less than 0.1 mm and not more than 3 mm. As described above, the first region is formed with a length of 3 mm or less, thereby reducing friction between the plurality of single core optical fibers and the ferrule in the first region having a small diameter, and disconnecting the plurality of single core optical fibers. Further reduction can be achieved. In addition, when the first region is 0.1 mm or more, the optical axis direction of the end portions of the plurality of single core optical fibers can be suitably aligned with the predetermined direction in the first region.

  An optical fiber branch device manufacturing method according to the present invention is a method for manufacturing any one of the above-described optical fiber branch devices, wherein the end portions of a plurality of single-core optical fibers are connected to the optical fiber from the other end side of the ferrule. An insertion step of collectively inserting into the third region of the insertion hole, and further inserting the plurality of single core optical fibers into the optical fiber insertion hole, An alignment step of aligning according to the arrangement of the plurality of optical axes of the optical component, and further inserting the plurality of single core optical fibers into the optical fiber insertion hole, while the end portions of the plurality of single core optical fibers are predetermined in the first region The end portions of the plurality of single core optical fibers and the end portions of the plurality of single core optical fibers and the inner surface of the optical fiber insertion hole. Characterized in that it comprises a bonding step of bonding the.

  In addition, the manufacturing method of the optical fiber branching device is a method of bundling the ends of a plurality of single-core optical fibers to form an optical fiber bundle, and interposing a liquid in a gap between the plurality of single-core optical fibers, and a plurality of liquids by surface tension of the liquid. A step of aggregating the ends of the single core optical fiber may be further provided before the insertion step. At this time, the ends of the plurality of single-core optical fibers are brought into close contact with each other by the surface tension of the liquid, so that they have the thinnest outer diameter corresponding to the number of single-core optical fibers and are compared with individual single-core optical fibers Thus, an optical fiber bundle having high elasticity can be obtained. Therefore, when this optical fiber bundle is inserted into the optical fiber insertion hole of the ferrule, it can be inserted very easily as compared with the case where a plurality of single core optical fibers are inserted individually.

  According to the optical fiber branch device and the manufacturing method of the optical fiber branch device according to the present invention, the end portions of the plurality of single core optical fibers can be easily inserted into the holes of the ferrule, and It is possible to suppress the optical loss between each optical axis of the optical component and the plurality of single-core optical fibers by arranging the end portions with high accuracy.

FIG. 1 is a perspective view showing an appearance of an optical fiber branch device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the ferrule included in the optical fiber branching device shown in FIG. 1 and shows a cross section along the longitudinal direction of the ferrule. FIG. 3 is an enlarged view of a cross section taken along line III-III of the optical fiber branching device shown in FIG. FIG. 4 is an enlarged view of a cross section taken along line IV-IV of the optical fiber branching device shown in FIG. FIG. 5A is a diagram showing a configuration in which three single-core optical fibers are arranged so as to contact each other. FIG. 5B is a diagram showing a form in which four single-core optical fibers are arranged in a diamond shape. FIG. 5C is a diagram showing a form in which 12 optical fibers are further arranged around 7 single-core optical fibers. FIG. 6 is a perspective view showing a state where seven single-core optical fibers and multi-core optical fibers are optically coupled to each other. FIG. 7 is a flowchart illustrating an example of a method of manufacturing an optical fiber branch device. Fig.8 (a)-FIG.8 (c) are figures which show typically the mode of the single core optical fiber in an optical fiber penetration hole. FIG. 9 is a diagram for explaining a modified example of the ferrule according to the embodiment. FIG. 10 is a flowchart showing a modification of the method of manufacturing the optical fiber branch device according to the embodiment. FIG. 11 is a cross-sectional view showing the structure of a ferrule included in the optical fiber branching device according to this modification, and shows a side cross section along a predetermined direction A. FIG. 12 is an enlarged view of a cross section of the optical fiber branching device taken along a cutting line corresponding to line III-III in FIG. FIG. 13 is an enlarged view of a cross section of the optical fiber branching device along a cutting line corresponding to line IV-IV in FIG. 1.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of an optical fiber branch device and a method for manufacturing an optical fiber branch device according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a perspective view showing an appearance of an optical fiber branch device 1A according to an embodiment of the present invention. 2 is a cross-sectional view of the ferrule 20A included in the optical fiber branching device 1A shown in FIG. 1, and shows a cross section along the longitudinal direction of the ferrule 20A. 3 is an enlarged view of a cross section taken along the line III-III of the optical fiber branching device 1A shown in FIG. 1, and FIG. 4 is a cross-sectional view of the optical fiber branching device 1A shown in FIG. It is an enlarged view of a section along line IV.

  The optical fiber branching device 1A is a component for optically coupling a plurality of single core optical fibers to an optical component having a plurality of optical axes, such as a multicore optical fiber. As shown in FIGS. 1, 3, and 4, the optical fiber branching device 1 </ b> A of this embodiment includes a plurality (seven in this embodiment) of single-core optical fibers 12, and the single-core optical fibers 12. And a ferrule 20A attached to the end.

  The ferrule 20A is a substantially columnar member made of, for example, zirconia or metal, and extends along a predetermined direction A. The ferrule 20A has an optical fiber insertion hole 22 extending along the predetermined direction A. The optical fiber insertion hole 22 penetrates from one end surface 20a of the ferrule 20A to the other end surface 20b, and a cross section perpendicular to the penetrating direction is circular. As shown in FIGS. 3 and 4, a plurality of single core optical fibers 12 are accommodated in the optical fiber insertion hole 22, and a plurality of single core optical fibers 12 and a plurality of single core optical fibers are accommodated. 12 and the ferrule 20A are fixed to each other by an adhesive 25. Further, as shown in FIG. 1, the end faces of the plurality of single core optical fibers 12 are exposed from one end face 20a of the ferrule 20A, and are arranged so as to be flush with the end face 20a. The plurality of single-core optical fibers 12 extend from the other end face 20b to the rear of the ferrule 20A.

  As shown in FIG. 2, the optical fiber insertion hole 22 includes a first region 22a, a second region 22b, and a third region 22c arranged in the predetermined direction A in order from the one end face 20a side. The first region 22a holds the ends of the plurality of single-core optical fibers 12 in accordance with the arrangement of a plurality of optical axes of optical components that are optical coupling targets (for example, the core arrangement of a multicore optical fiber). Therefore, the inner diameter of the first region 22a is relatively narrow. Further, the inner surface of the first region 22a extends along the predetermined direction A (that is, the penetration direction of the optical fiber insertion hole 22), and is preferably formed parallel to the predetermined direction A.

  As shown in FIG. 3, in the first region 22a, one of the seven single-core optical fibers 12 having the same outer diameter is disposed at the center, and the remaining six single-core optical fibers are disposed around the center. The fibers 12 are arranged in contact with the single-core optical fiber 12 in the center and in contact with each other. Such an arrangement is an arrangement (closest arrangement) in which the existence density of the single core optical fibers 12 is highest in a cross section perpendicular to the longitudinal direction of the single core optical fibers 12. Note that the close-packed arrangement of the plurality of single-core optical fibers 12 is not limited to such a form. For example, as shown in FIG. 5A, three single-core optical fibers 12 are arranged so as to be in contact with each other. Alternatively, as shown in FIG. 5B, four single core optical fibers 12 are arranged in a diamond shape, or around the seven single core optical fibers 12 as shown in FIG. 5C. Further, a configuration in which 12 optical fibers are further arranged is included in the close-packed arrangement. That is, the close-packed arrangement mentioned here is an arrangement including one or a plurality of unit structures 14 in which three single core optical fibers 12 are in contact with each other. For example, in the form shown in FIG. 5B, two unit structures 14 are included in the form shown in FIG. 5B, and six unit structures 14 are included in the form shown in FIG. 3 (FIG. 3). And only one unit structure 14 is shown in FIG. 5).

  In one form, the difference between the outer diameter of the optical fiber bundle formed by bundling the ends of the plurality of single-core optical fibers 12 and the inner diameter of the first region 22a of the optical fiber insertion hole 22 (that is, the first The width of the gap between the inner surface of the region 22a and the surface of the optical fiber bundle is larger than 0 μm and smaller than 5 μm. The outer diameter of the optical fiber bundle composed of the seven single core optical fibers 12 is equal to the sum of the outer diameters of the three single core optical fibers 12. Further, the length of the first region 22a in the predetermined direction A is preferably 0.1 mm or more, and preferably 3 mm or less.

  Each of the plurality of single core optical fibers 12 includes one core 12a and a clad 12b provided around the core 12a. As the single-core optical fiber 12, a configuration such as a plastic optical fiber made of plastic in addition to a glass fiber made of quartz glass can be adopted.

  The third region 22c holds the plurality of single core optical fibers 12 with a certain gap (see FIG. 4). Therefore, the inner diameter of the third region 22c is relatively wide and is larger than the inner diameter of the first region 22a. The ratio (D1 / D3) between the inner diameter D1 of the first region 22a and the inner diameter D3 of the third region 22c is preferably 0.60 or more and 0.95 or less. Further, the inner surface of the third region 22c extends along the predetermined direction A (that is, the penetrating direction of the optical fiber insertion hole 22) similarly to the inner surface of the first region 22a, and preferably with respect to the predetermined direction A. They are formed in parallel. In addition, it is preferable that the length of the 3rd area | region 22c in the predetermined direction A is 0.3 mm or more, and it is preferable that it is 8.0 mm or less. Further, it is desirable that a tapered portion 22d for facilitating insertion of the plurality of single core optical fibers 12 is formed between the third region 22c and the end surface 20b.

  As shown in FIG. 2, in the predetermined direction A, the second region 22b is formed between a first region 22a having a relatively narrow inner diameter and a third region 22c having a relatively wide inner diameter. And the internal diameter of the 2nd area | region 22b has expanded in the taper shape toward the 3rd area | region 22c side from the 1st area | region 22a side. Here, the taper shape means that, for example, the inner surface of the second region 22b has a shape of a side surface of a truncated cone. In other words, one end of the second region 22b (typically, the boundary with the first region 22a). ) With respect to the predetermined direction A and the inner diameter D2 of the second region 22b at the position satisfy D2 = k × x (where k> 1). In the present embodiment, the cross-sectional shape of the inner surface of the second region 22b along the predetermined direction A is linear (tapered). However, this cross-sectional shape is not limited to a linear shape, but is a bent shape or a curved shape. The shape may be sufficient. However, the angle θ (see FIG. 2) formed between the inner surface of the second region 22b and the predetermined direction A is 10 ° or less, and the inner surface of the second region 22b is bent or curved in the predetermined direction A. However, the maximum value of the angle θ is suppressed to 10 ° or less.

  Moreover, the internal diameter in the end by the side of the end surface 20a of the 2nd area | region 22b is equal to the internal diameter D1 of the 1st area | region 22a. Further, the inner diameter at one end of the second region 22b on the end face 20b side is equal to the inner diameter D3 of the third region 22c. Accordingly, the joint between the first region 22a and the second region 22b and the joint between the second region 22b and the third region 22c are continuous, and no step is provided.

  Here, when the plurality of single-core optical fibers 12 and the multi-core optical fiber are optically coupled, one end face 20a of the ferrule 20A described above and the end face of another ferrule attached to the tip of the multi-core optical fiber are Abut each other. FIG. 6 is a perspective view showing a state where seven single-core optical fibers 12 and multi-core optical fibers 30 are optically coupled to each other. In FIG. 6, there are gaps between the seven single-core optical fibers 12 and the multi-core optical fibers 30 for easy understanding. However, actually, the single-core optical fibers 12 and the multi-core optical fibers 30 Are preferably close to each other.

  As shown in FIG. 6, the ends of the seven single-core optical fibers 12 are preferably optically coupled to a multi-core optical fiber 30 having seven cores. The multi-core optical fiber 30 has one central core 30a and six peripheral cores 30b arranged at equal intervals on the circumference centered on the central core. The distance between the center of the central core 30 a and the center of the peripheral core 30 b and the distance between the centers of the adjacent peripheral cores 30 b are equal to the outer diameter of the single core optical fiber 12. The central core 30a is optically coupled to the core of one single-core optical fiber 12 disposed at the center of the optical fiber bundle, and the peripheral core 30b includes the other six cores excluding the single-core optical fiber 12. Each core of the single core optical fiber 12 is optically coupled.

  Hereinafter, an example of a method for manufacturing the optical fiber branching device 1A having such a configuration will be described. FIG. 7 is a flowchart showing an example of a manufacturing method of the optical fiber branching device 1A. FIGS. 8A to 8C are diagrams schematically showing the state of the single core optical fiber 12 in the optical fiber insertion hole 22. In the present embodiment, first, a plurality of single-core optical fibers 12 are collectively inserted into the third region 22c of the optical fiber insertion hole 22 of the ferrule 20A from the end face 20b side (insertion step, S11 in FIG. 7). At this time, as shown in FIG. 8A, the plurality of single-core optical fibers 12 are present in the third region 22c in a state of being largely separated from each other.

  Subsequently, the plurality of single core optical fibers 12 are further inserted into the optical fiber insertion hole 22. At this time, as shown in FIG. 8B and FIG. 8C, the end portions of the plurality of single-core optical fibers 12 gradually gather along the inner surface of the second region 22b that gradually decreases in diameter in a tapered shape. , The distance between each other is shortened. When the end portions of the plurality of single core optical fibers 12 reach the boundary portion between the second region 22b and the first region 22a, the ends of the plurality of single core optical fibers 12 are shown in FIG. 8D. The parts are aligned according to the arrangement of a plurality of optical axes of the optical component to be optically coupled (for example, the core arrangement of the multi-core optical fiber 30 shown in FIG. 6) (alignment step, S12 in FIG. 7).

  Subsequently, the plurality of single core optical fibers 12 are further inserted into the optical fiber insertion hole 22, and the ends of the plurality of single core optical fibers 12 are accommodated in the first region 22a. At this time, since the inner surface of the first region 22a extends along the predetermined direction A, the ends of the plurality of single-core optical fibers 12 have a shape along the predetermined direction A (S13 in FIG. 7).

  Thereafter, an adhesive is poured into the optical fiber insertion hole 22 to bond the end portions of the plurality of single core optical fibers 12 and the end portions of the plurality of single core optical fibers 12 to the inner surface of the optical fiber insertion hole 22. (Adhesion process, S14 in FIG. 7). In addition, as an adhesive agent of this process, an acrylic type, an epoxy type, a silicone type adhesive agent etc. are used suitably, for example. Through the above steps, the optical fiber branch device 1A according to this embodiment is manufactured.

  The effects obtained by the fiber branch device 1A according to the present embodiment and the manufacturing method thereof described above will be described. In the optical fiber branching device 1A, the optical fiber insertion hole 22 of the ferrule 20A includes a first region 22a, a second region 22b, and a third region 22c. And the edge part of the several single core optical fiber 12 can be collectively inserted from the 3rd area | region 22c with a comparatively large internal diameter. Thereby, the insertion of the plurality of single core optical fibers 12 into the optical fiber insertion hole 22 is facilitated, and disconnection in the insertion process can be reduced.

  The end portions of the plurality of single core optical fibers 12 thus inserted into the third region 22c then pass through the second region 22b. Since the inner diameter of the second region 22b extends, for example, in a tapered shape from the first region 22a side to the third region 22c side, as described above, the end portions of the plurality of single core optical fibers 12 are in the second region. While being guided to the inner surface of 22b, it proceeds through the second region 22b which becomes gradually thinner. Thereby, when the end portions of the plurality of single core optical fibers 12 reach the third region 22c, the ends of the plurality of single core optical fibers 12 are accommodated in the relatively narrow optical fiber insertion holes 22, The ends of these single core optical fibers 12 are aligned according to the arrangement of a plurality of optical axes of optical components to be optically coupled (for example, the core arrangement of the multicore optical fiber 30) (see FIG. 8D). ). Thereafter, when the plurality of single-core optical fibers 12 are further inserted into the optical fiber insertion holes 22, the inner surface of the first region 22a is along the predetermined direction A. The optical axis direction has a shape (preferably parallel) along the predetermined direction A in the first region 22a. In this way, the ends of the plurality of single core optical fibers 12 are accurately arranged, and optical loss between each optical axis of the optical component (for example, each core of the multicore optical fiber 30) and the plurality of single core optical fibers 12 is suppressed. It is done.

  Thus, according to the optical fiber branching device 1A and the manufacturing method thereof, the end portions of the plurality of single core optical fibers 12 can be easily inserted into the optical fiber insertion holes 22 of the ferrule 20A, and a plurality of single fibers The end of the core optical fiber 12 can be arranged with high accuracy, and light loss between each optical axis of the optical component (for example, each core of the multi-core optical fiber 30) and the plurality of single-core optical fibers 12 can be suppressed.

In the present embodiment, the angle θ (see FIG. 2) formed by the inner surface of the second region 22b and the predetermined direction A is 10 ° or less. Here, it is a table | surface which shows the result of having investigated the relationship between the insertion ease of several single core optical fiber 12, and angle (theta).

As shown in Table 1, a plurality of single-core optical fibers 12 could be smoothly inserted from the other end side to one end side of the optical fiber insertion hole 22 when the angle θ was in the range of 0 ° to 10 °. (○ mark). On the other hand, when the angle θ is in the range of 15 ° or more and 20 ° or less, when the plurality of single core optical fibers 12 are inserted from the other end side of the optical fiber insertion hole 22 to one end side, they can be inserted to one end side. There was a case where it was not possible (× mark). In addition, when the angle θ is in the range of 25 ° or more, the single core optical fiber 12 is caught on the inner surface of the optical fiber insertion hole 22 and cannot be inserted to one end side of the optical fiber insertion hole 22 (× mark). . Thus, the ease of insertion of the single-core optical fiber 12 greatly depends on the angle θ, and when the angle θ is 10 ° or less, the single-core optical fiber 12 is smoothly inserted to one end side of the optical fiber insertion hole 22. can do.

  Further, as in the present embodiment, in the first region 22a, the difference between the outer diameter of the optical fiber bundle formed by bundling the ends of the plurality of single core optical fibers 12 and the inner diameter of the optical fiber insertion hole 22 is 0 μm. It is preferably larger and less than 3 μm. Thus, by narrowing the gap between the inner surface of the first region 22a and the optical fiber bundle, the end portions of the plurality of single core optical fibers 12 can be more suitably aligned.

  Further, as in this embodiment, the length of the first region 22a in the predetermined direction A is preferably 0.1 mm or more, and preferably 3 mm or less. By forming the first region 22a to be as short as 3 mm or less, the friction between the plurality of single core optical fibers 12 and the ferrule 20A in the first region 22a having a small diameter is reduced, and the disconnection of the plurality of single core optical fibers 12 is performed. Can be further reduced. In addition, when the first region 22a is 0.1 mm or more, the optical axis direction of the end portions of the plurality of single core optical fibers 12 can be suitably aligned with the predetermined direction A in the first region 22a.

(First modification)
FIG. 9 is a diagram for explaining a modified example of the ferrule 20A according to the embodiment. FIG. 9A is the form described in the above embodiment, and the inner surface of the second region 22b extends linearly from the boundary with the first region 22a to the boundary with the third region 22c. . The inner surface of the first region 22a and the inner surface of the second region 22b intersect at an angle θ. Similarly, the inner surface of the second region 22b and the inner surface of the third region 22c intersect at an angle θ.

  On the other hand, FIG. 9B is a modified example of the ferrule 20A shown in FIG. 9A, in which the inner surface of the first region 22a and the inner surface of the second region 22b are curved surfaces (curvature radius R). ) Is connected smoothly. Similarly, the inner surface of the second region 22b and the inner surface of the third region 22c are smoothly connected via a curved surface (curvature radius R). As described above, the inner surface of the first region 22a and the inner surface of the second region 22b and / or the inner surface of the second region 22b and the inner surface of the third region 22c are passed through a curved surface curved in a plane including the predetermined direction A. They may be smoothly connected to each other. Thereby, the catch in the boundary part of the 1st area | region 22a, the 2nd area | region 22b, and the 3rd area | region 22c at the time of inserting the several single core optical fiber 12 can be reduced, and the disconnection in an insertion process can be reduced more. .

(Second modification)
FIG. 10 is a flowchart showing a modification of the method for manufacturing the optical fiber branch device 1A according to the embodiment. In this modification, first, end portions of a plurality of single-core optical fibers 12 are bundled to form an optical fiber bundle, and a plurality of single-core optical fibers 12 are intervened in a gap between the plurality of single-core optical fibers 12 and the plurality of single-core optical fibers 12 are separated by the surface tension of the liquid. The ends of the core optical fiber 12 are aggregated (end aggregation process S21). As the liquid used at this time, a liquid having a relatively low viscosity is preferable, and various kinds of liquids are applied. Examples of the liquid used in this step include water, liquids containing alcohol solvents, volatile liquids (hydrocarbon solvents, ester solvents, ketone solvents, ether solvents, etc.), and these Mixtures are preferred. Water and alcohol solvents have the advantage of high surface tension while taking a long time for the drying process. Moreover, if a volatile liquid is used, a drying process can be shortened. That is, the type of liquid and the mixing ratio may be changed as appropriate according to the manufacturing process.

  Examples of the alcohol solvent include methanol, ethanol, butanol, IPA (isopropyl alcohol), normal propyl alcohol, butanol, isobutanol, TBA (tertiary butanol), butanediol, ethylhexanol, and benzyl alcohol. Examples of ester solvents include ethyl acetate, methyl acetate, butyl acetate, methoxybutyl acetate, cellosolve acetate, amyl acetate, normal propyl acetate, isopropyl acetate, methyl lactate, ethyl lactate, and butyl lactate. Examples of the hydrocarbon solvent include toluene, xylene, solvent naphtha, normal hexane, isohexane, cyclohexane, methylcyclohexane, normal heptane, isooctane, and normal decane. Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, DIBK (diisobutyl ketone), cyclohexanone, and DAA (diacetone alcohol). Examples of the ether solvent include methyl cellosolve, cellosolve, butyl cellosolve, dioxane, MTBE (methyl tertiary butyl ether), and butyl carbitol.

  Subsequently, steps S11 to S13 shown in FIG. 7 are sequentially performed. In the present modification, the optical fiber bundle composed of the plurality of single core optical fibers 12 is aggregated with the minimum outer diameter by the end aggregation step S21. Therefore, the plurality of single core optical fibers 12 can be easily inserted into the optical fiber insertion hole 22 (particularly, the first region 22a having a small diameter).

  After step S13, the liquid is dried in a state where the plurality of single core optical fibers 12 are inserted into the optical fiber insertion holes 22 (drying step S22). In this step, drying is performed to remove the liquid from the gaps between the plurality of single core optical fibers 12. By removing the liquid, gaps between the plurality of single core optical fibers 12 become air gaps. Therefore, the end portions of the plurality of single core optical fibers 12 aggregated in the end portion aggregation step S21 are once separated from each other. Thereafter, an adhesive is poured into the optical fiber insertion hole 22, and the single core optical fibers 12 and the single core optical fiber 12 and the optical fiber insertion hole 22 are bonded to each other (bonding step S14).

  According to this modification, the end portions of the plurality of single-core optical fibers 12 are brought into close contact with each other by the surface tension of the liquid, and therefore have the thinnest outer diameter corresponding to the number of single-core optical fibers 12 and An optical fiber bundle having a higher elasticity than that of the core optical fiber 12 is obtained. Therefore, this optical fiber bundle can be very easily inserted into the optical fiber insertion hole 22 of the ferrule 20A.

(Third Modification)
Then, the 3rd modification of the said embodiment is demonstrated. FIG. 11 is a cross-sectional view showing the structure of the ferrule 20B included in the optical fiber branching device 1B according to the present modification, and shows a side cross section along the predetermined direction A. 12 is an enlarged view of a cross section of the optical fiber branching device 1B along a cutting line corresponding to the line III-III in FIG. 1, and FIG. 13 is a cutting line corresponding to the line IV-IV in FIG. It is an enlarged view of the cross section of the optical fiber branching device 1B along line.

  The difference between this modified example and the above embodiment is the shape of the optical fiber insertion hole of the ferrule. That is, the ferrule 20B according to this modification has an optical fiber insertion hole 24 instead of the optical fiber insertion hole 22 of the above embodiment. As shown in FIGS. 11 to 13, the fiber insertion hole 24 extends in a predetermined direction A (that is, the penetration direction of the optical fiber insertion hole 24), and penetrates from one end surface 20a of the ferrule 20B to the other end surface 20b. doing. And the cross section perpendicular | vertical with respect to the penetration direction of the optical fiber penetration hole 24 is polygonal shape (in the figure hexagonal shape).

  As shown in FIGS. 12 and 13, a plurality of single core optical fibers 12 are accommodated in the optical fiber insertion hole 24, and a plurality of single core optical fibers 12 and a plurality of single core optical fibers are accommodated. 12 and the ferrule 20A are fixed to each other by an adhesive 25. And as FIG. 11 shows, the optical fiber penetration hole 24 contains the 1st area | region 24a, the 2nd area | region 24b, and the 3rd area | region 24c which were located in a line in the predetermined direction A in order from the one end surface 20a side. In addition, the shape of these area | regions 24a-24c is the same as that of the said embodiment except for cross-sectional shape (whether circular or polygonal).

  As in this modification, the cross-sectional shape of the optical fiber insertion hole is not limited to the circular shape as in the above embodiment, and may be various shapes such as a polygon. In particular, a plurality of single-core optical fibers 12 are formed by adopting a shape that matches the number of single-core optical fibers 12 (for example, a hexagonal cross section with respect to seven single-core optical fibers 12) as in this modification. It can be aligned more effectively.

  The preferred embodiments of the optical fiber branching device and the manufacturing method thereof according to the present invention have been described above. However, the present invention is not necessarily limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, in the above-described embodiment, a multi-core optical fiber is exemplified as an optical component that is an optical coupling target. However, the optical component that is an optical coupling target in the present invention only needs to have a plurality of optical axes. A light emitting element such as a bundle of core optical fibers or a vertical cavity surface emitting laser (VCSEL) having a plurality of light emitting portions may be used.

  DESCRIPTION OF SYMBOLS 1A, 1B ... Optical fiber branching device, 12 ... Single core optical fiber, 12a ... Core, 12b ... Cladding, 14 ... Unit structure, 20A, 20B ... Ferrule, 22, 24 ... Optical fiber insertion hole, 22a, 24a ... First Region 22b, 24b ... second region, 22c, 24c ... third region, 22d ... taper, 25 ... adhesive, 30 ... multi-core optical fiber, 30a ... central core, 30b ... peripheral core, A ... predetermined direction.

Claims (6)

An optical fiber branching device for optically coupling a plurality of single core optical fibers to an optical component having a plurality of optical axes,
Comprising a ferrule having an optical fiber insertion hole that accommodates ends of the plurality of single-core optical fibers;
The optical fiber insertion hole penetrates the ferrule in a predetermined direction, and end surfaces of the plurality of single core optical fibers are exposed from one end side of the ferrule in the predetermined direction,
The optical fiber insertion hole includes a first region, a second region and a third region arranged in the predetermined direction in order from the one end side,
The first region holds the ends of the plurality of single core optical fibers according to the arrangement of the plurality of optical axes of the optical component, and the inner surface of the first region is along the predetermined direction,
The inner diameter of the third region is larger than the inner diameter of the first region, and the inner surface of the third region is along the predetermined direction,
The inner diameter of the second region extends from the first region side toward the third region side,
The optical fiber branching device is characterized in that an angle formed between the inner surface of the second region and the predetermined direction is 10 ° or less.   In the first region, a difference between an outer diameter of an optical fiber bundle formed by bundling ends of the plurality of single core optical fibers and an inner diameter of the optical fiber insertion hole is greater than 0 μm and less than 3 μm. The optical fiber branching device according to claim 1.   In the first region, ends of the plurality of single core optical fibers are arranged so as to include one or a plurality of unit structures in which the three single core optical fibers are in contact with each other. Item 3. The optical fiber branching device according to Item 1 or 2.   The length of the said 1st area | region in the said predetermined direction is 0.1 mm or more and 3 mm or less, The optical fiber branching device as described in any one of Claims 1-3 characterized by the above-mentioned. A method of manufacturing an optical fiber branching device according to any one of claims 1 to 4,
An insertion step of collectively inserting the end portions of the plurality of single-core optical fibers into the third region of the optical fiber insertion hole from the other end side of the ferrule;
While further inserting the plurality of single core optical fibers into the optical fiber insertion hole, the ends of the plurality of single core optical fibers are aligned in the second region according to the arrangement of the plurality of optical axes of the optical component. An aligning step,
While further inserting the plurality of single core optical fibers into the optical fiber insertion hole, the step of aligning the end of the plurality of single core optical fibers in the predetermined direction in the first region;
The light comprising: bonding steps for bonding the ends of the plurality of single-core optical fibers together, and the ends of the plurality of single-core optical fibers and the inner surface of the optical fiber insertion hole, A method of manufacturing a fiber branch device.   The ends of the plurality of single-core optical fibers are bundled to form an optical fiber bundle, and a liquid is interposed in the gap between the plurality of single-core optical fibers, and the ends of the plurality of single-core optical fibers are caused by surface tension of the liquid. The method for manufacturing an optical fiber branching device according to claim 5, further comprising a step of aggregating the parts before the inserting step.