Multicore optical connector and method for manufacturing multicore optical connector

Abstract

This multicore optical connector (1A) is provided with a ferrule (20), a rubber boot (30), a first resin adhesive (41), and a second resin adhesive (42). The ferrule (20) has a plurality of first accommodation holes (21) and a second accommodation hole (22). Each first accommodation hole (21) accommodates each optical fiber (10). The second accommodation hole (22) includes a second opening (22a) formed in a rear end surface and communicates with the plurality of first accommodation holes (21). The second accommodation hole (22) accommodates a plurality of optical fibers (10). The boot (30) has an insertion hole (31), into which the plurality of optical fibers is inserted, and is fitted into the second opening. The first resin adhesive (41) fixes the plurality of optical fibers to the ferrule. The second resin adhesive (42) adheres to the outer peripheral surfaces of portions passing through the insertion hole of at least two optical fibers among the plurality of optical fibers, and fixes the portions of the at least two optical fibers to each other. The second resin adhesive (42) is interposed between the inner surface of the insertion hole and the outer peripheral surfaces of the at least two optical fibers. Each of the plurality of optical fibers (10) is separated from each other behind the second resin adhesive.

Description

Multi-core optical connector and method of manufacturing the same

[0001] This disclosure relates to a multi-fiber optical connector and a method for manufacturing the same. This application claims priority to Japanese Application No. 2024-026536, filed June 26, 2024, and incorporates by reference all of the contents of that application.

[0002] Patent Document 1 discloses an optical connector. This optical connector includes a plurality of optical fibers and a ferrule that houses at least some of the plurality of optical fibers. The ferrule has a front end face, an opening on the opposite side from the front end face for receiving the plurality of optical fibers, and a plurality of holding holes extending to the front end face for holding each of the plurality of optical fibers. Patent Document 2 discloses a ribbon core wire with a multi-fiber connector.

[0003] International Publication No. 2018 / 135368 Japanese Patent Application Laid-Open No. 2014-52490

[0004] A multi-fiber optical connector according to one embodiment of the present disclosure includes a plurality of optical fibers, a ferrule, a rubber boot, a first resin adhesive, and a second resin adhesive. The ferrule has a front end face, a rear end face, a plurality of first receiving holes, and a second receiving hole. Each of the first receiving holes includes a first opening formed in the front end face and receives a respective one of the optical fibers. The second receiving hole includes a second opening formed in the rear end face and communicates with the first receiving holes. The second receiving hole receives the plurality of optical fibers. The boot has an insertion hole through which the plurality of optical fibers are inserted and fits into the second opening. The first resin adhesive is received in the first and second receiving holes and secures the plurality of optical fibers to the ferrule. The second resin adhesive adheres to the outer peripheral surfaces of portions of at least two of the plurality of optical fibers that pass through the insertion hole and secures the portions of the at least two optical fibers to each other. The second resin adhesive is interposed between the inner surface of the insertion hole and the outer peripheral surfaces of the at least two optical fibers. The optical fibers are separated from one another behind the second resin adhesive.

[0005] FIG. 1 is a perspective view showing the appearance of a multi-fiber optical connector according to an embodiment of the present disclosure. FIG. 2 is a cross-sectional view of the multi-fiber optical connector taken along line II-II in FIG. 1. FIG. 3 is a cross-sectional view of the multi-fiber optical connector taken along line III-III in FIG. 2. FIG. 4 is a flowchart showing an example of a method for manufacturing a multi-fiber optical connector. FIG. 5 is a flowchart showing an example of a method for manufacturing a multi-fiber optical connector. FIG. 6 is a diagram showing a state in which a first resin adhesive has leaked. FIG. 7 is a cross-sectional view of a multi-fiber optical connector according to a first modified example taken along a line corresponding to line II-II in FIG. 1. FIG. 8 is a cross-sectional view of the multi-fiber optical connector taken along line VIII-VIII in FIG. 7. FIG. 9 is a side cross-sectional view of a multi-fiber optical connector according to a second modified example, showing a cross section of the multi-fiber optical connector taken along the YZ plane. FIG. 10 is a perspective view showing an example of a holding member. FIG. 11 is a perspective view showing an example of a holding member. FIG. 12 is a perspective view showing an example of a holding member. FIG. 13 is a flowchart showing an example of a method for manufacturing a multi-fiber optical connector according to a second modified example. FIG. 14 is a flowchart showing an example of a method for manufacturing a multi-fiber optical connector according to the second modified example.

[0006] [Problem to be Solved by the Present Disclosure] Generally, when manufacturing a multi-fiber optical connector, multiple optical fibers are inserted into an opening formed at the rear end of a ferrule having multiple receiving holes formed at the front end, and each optical fiber is inserted into each receiving hole. At this time, uncured resin adhesive for fixing each optical fiber in each receiving hole is placed inside the ferrule in advance. After the multiple optical fibers are inserted into the ferrule, the opening at the rear end of the ferrule is closed with a rubber boot to prevent the resin adhesive from leaking from the opening. The resin adhesive is then cured.

[0007] However, the boot is formed with an insertion hole for inserting multiple optical fibers. Therefore, the resin adhesive may leak out of the ferrule through a gap between the insertion hole and the multiple optical fibers. If the resin adhesive is a heat-curing type, the viscosity of the resin adhesive temporarily decreases during the temperature rise process during curing, making the resin adhesive more likely to leak through the gap between the insertion hole and the multiple optical fibers. In addition, if the optical fibers are of a type that requires rotational alignment, such as a multicore fiber or polarization-maintaining fiber, the multiple optical fibers must be inserted into the ferrule while separated from one another. In such a case, the gap between the insertion hole and the multiple optical fibers becomes larger, making the resin adhesive more likely to leak.

[0008] If the resin adhesive leaks out of the ferrule through the gap between the insertion hole and the multiple optical fibers, the resin adhesive has very low flexibility after hardening, which can cause the optical fibers to break because it cannot absorb the bending stress of the optical fibers.Furthermore, there is also the problem that the resin adhesive leaking out of the ferrule can mar the appearance of the multi-fiber optical connector.

[0009] An object of the present disclosure is to provide a multi-core optical connector and a method for manufacturing a multi-core optical connector that can reduce the amount of resin adhesive leaking from gaps between the boot insertion hole and multiple optical fibers.

[0010] Effect of the Present Disclosure The present disclosure provides a multi-core optical connector and a method for manufacturing a multi-core optical connector that can reduce the amount of resin adhesive leaking from gaps between the boot insertion holes and the plurality of optical fibers.

[0011] [Description of Embodiments of the Present Disclosure] First, the contents of the embodiments of the present disclosure will be listed and described. [1] A multi-fiber optical connector according to one embodiment of the present disclosure includes a plurality of optical fibers, a ferrule, a rubber boot, a first resin adhesive, and a second resin adhesive. The ferrule has a front end face, a rear end face, a plurality of first receiving holes, and a second receiving hole. Each of the plurality of first receiving holes includes a first opening formed in the front end face and receives a respective one of the plurality of optical fibers. The second receiving hole includes a second opening formed in the rear end face and communicates with the plurality of first receiving holes. The second receiving hole receives a plurality of optical fibers. The boot has an insertion hole into which the plurality of optical fibers are inserted and fits into the second opening. The first resin adhesive is received in the plurality of first receiving holes and the second receiving hole, and fixes the plurality of optical fibers to the ferrule. The second resin adhesive adheres to the outer peripheral surfaces of portions of at least two of the plurality of optical fibers that pass through the insertion holes, and fixes these portions of the at least two optical fibers to each other. The second resin adhesive is interposed between the inner surface of the insertion hole and the outer circumferential surfaces of the at least two optical fibers, and the optical fibers are separated from each other behind the second resin adhesive.

[0012] In the multi-fiber optical connector of [1] above, a second resin adhesive is interposed between the inner surface of the insertion hole of the boot and the outer peripheral surfaces of at least two optical fibers. This second resin adhesive hardens before the first resin adhesive, thereby narrowing the gap between the insertion hole and the multiple optical fibers when the first resin adhesive hardens. Therefore, the multi-fiber optical connector of [1] above can reduce the amount of first resin adhesive leaking from the gap between the insertion hole and the multiple optical fibers.

[0013] [2] In the multi-fiber optical connector of [1] above, the outer diameter of each of the optical fibers in the insertion hole may be smaller than the center-to-center spacing of the first receiving holes. In this case, the gap between the insertion hole and the optical fibers becomes larger, and the first resin adhesive is likely to leak if the second resin adhesive is not used. In such a case, the presence of the second resin adhesive is more effective.

[0014] [3] In the multi-fiber optical connector of [1] or [2] above, the optical fibers may form a ribbon at a distance of 100 mm or more rearward from the boot, and may be separated from one another between the ribbon and the boot. For example, if the optical fibers are a type of optical fiber that requires rotational alignment, such as a multicore fiber or a polarization-maintaining fiber, the jacket of the ribbon is removed from the boot over a long section, e.g., 100 mm or more, to separate the optical fibers from one another for rotational alignment of each optical fiber. In such cases, the presence of the second resin adhesive is more effective.

[0015] [4] The multi-fiber optical connectors according to [1] to [3] above may further include a protective member that covers the optical fibers behind the boot. In this case, the separated optical fibers can be combined into one.

[0016] [5] A method for manufacturing a multi-fiber optical connector according to an embodiment of the present disclosure includes a first step, a second step, a third step, a fourth step, and a fifth step. In the first step, a ferrule is prepared. The ferrule has a front end face, a rear end face, and a plurality of first receiving holes and a second receiving hole. Each of the plurality of first receiving holes includes a first opening formed in the front end face. The second receiving hole includes a second opening formed in the rear end face and communicates with the plurality of first receiving holes. In the second step, a first resin adhesive is placed in the second receiving hole, and a plurality of optical fibers separated from each other are inserted into the second receiving hole, and each of the plurality of optical fibers is inserted into each of the plurality of first receiving holes. In the third step, a second resin adhesive is applied to the outer peripheral surfaces of portions of at least two of the plurality of optical fibers and cured, thereby fixing the portions of the at least two optical fibers to each other with the second resin adhesive. In a fourth step, a rubber boot having insertion holes is fitted into the second opening, and the optical fibers and the second resin adhesive are placed in the insertion holes. In a fifth step, the first resin adhesive is cured to fix the optical fibers to the ferrule.

[0017] [6] A method for manufacturing a multi-fiber optical connector according to another embodiment of the present disclosure includes a first step, a second step, a third step, a fourth step, and a fifth step. In the first step, a ferrule is prepared. The ferrule has a front end face, a rear end face, and a plurality of first receiving holes and a second receiving hole. Each of the plurality of first receiving holes includes a first opening formed in the front end face. The second receiving hole includes a second opening formed in the rear end face and communicates with the plurality of first receiving holes. In the second step, a first resin adhesive is placed in the second receiving hole, and a second resin adhesive is applied to the outer peripheral surfaces of portions of at least two optical fibers among the plurality of optical fibers that are separated from each other and cured, thereby fixing the portions of the at least two optical fibers together with the second resin adhesive. In the third step, a plurality of optical fibers are inserted into the second receiving hole, and a plurality of optical fibers are inserted into each of the plurality of first receiving holes. In a fourth step, a rubber boot having insertion holes is fitted into the second opening, and the optical fibers and the second resin adhesive are placed in the insertion holes. In a fifth step, the first resin adhesive is cured to fix the optical fibers to the ferrule.

[0018] In the manufacturing methods [5] and [6] above, in the fifth step of curing the first resin adhesive, the already cured second resin adhesive is interposed between the inner surface of the insertion hole of the boot and the outer peripheral surfaces of at least two optical fibers. Therefore, the gap between the insertion hole and the multiple optical fibers is narrowed when the first resin adhesive is cured. This reduces the amount of first resin adhesive leaking from the gap between the insertion hole and the multiple optical fibers. In the present disclosure, the term "separated from each other" refers to a state in which the coatings of adjacent optical fibers are not adhered to each other, such as in a state in which the outer coating of a ribbon core wire has been removed.

[0019] [Details of the embodiments of the present disclosure] Specific examples of the present disclosure will be described below with reference to the drawings. The present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. In the following description, the same elements in the description of the drawings will be given the same reference numerals, and duplicate explanations will be omitted.

[0020] FIG. 1 is a perspective view showing the appearance of a multi-fiber optical connector 1A according to an embodiment of the present disclosure. FIG. 2 is a cross-sectional view of the multi-fiber optical connector 1A taken along line II-II in FIG. 1. FIG. 3 is a cross-sectional view of the multi-fiber optical connector 1A taken along line III-III in FIG. 2. For ease of understanding, arrows indicating the X, Y, and Z directions are shown in these figures. The X direction indicates the lateral direction of the multi-fiber optical connector 1A. The Y direction indicates the thickness direction of the multi-fiber optical connector 1A. The Z direction indicates the front direction of the multi-fiber optical connector 1A. Vectors in the X, Y, and Z directions intersect with each other, and in one example, the vectors in the X, Y, and Z directions are orthogonal to each other.

[0021] As shown in Figures 1, 2 and 3, the multi-core optical connector 1A comprises a plurality of optical fibers 10, a ferrule 20, a boot 30, a first resin adhesive 41, a second resin adhesive 42, and a tube 50 (shown only in Figure 2).

[0022] The optical fibers 10 are arranged in one or more layers, and in the illustrated example, two layers are arranged. When the optical fibers 10 are arranged in multiple layers, the multiple layers are arranged in the Y direction. In each layer, the optical fibers 10 are arranged in the X direction, and each optical fiber 10 extends in the Z direction. As shown in FIG. 3 , each optical fiber 10 includes a glass fiber 11 and a resin coating 12 covering the glass fiber 11. The diameter of the glass fiber 11 is, for example, 125 μm. The outer diameter of the resin coating 12 is, for example, 250 μm. In this embodiment, the resin coatings 12 of adjacent optical fibers 10 in each layer are in contact with each other. As shown in FIG. 2 , each optical fiber 10 includes a coating portion 10a including the glass fiber 11 and the resin coating 12, and a core portion 10b in which the resin coating 12 has been removed and the glass fiber 11 is exposed from the resin coating 12. The core portion 10b is located forward (in the Z direction) of the coating portion 10a. The core portion 10 b includes the tip end surface of the glass fiber 11 .

[0023] The ferrule 20 is a resin member having a substantially rectangular parallelepiped shape. The ferrule 20 is, for example, an MT ferrule. The ferrule 20 has a front end face 20a, a rear end face 20b, a plurality of first accommodating holes 21, and a second accommodating hole 22. The front end face 20a is located at the front end of the ferrule 20 in the Z direction. The rear end face 20b is located at the rear end of the ferrule 20 in the opposite direction to the Z direction. Each of the first accommodating holes 21 extends along the Z direction inside the ferrule 20, reaches the front end face 20a, and includes a first opening 21a formed in the front end face 20a. The tip end faces of the glass fibers 11 are exposed to the outside of the ferrule 20 through the first opening 21a. Each of the first accommodating holes 21 accommodates a corresponding one of the optical fibers 10. The arrangement of the first accommodating holes 21 in the XY cross section is the same as the arrangement of the glass fibers 11 of the optical fibers 10 in the same cross section.

[0024] The optical fibers 10 are not tapered and are separated from one another in a certain length section behind the second resin adhesive 42 described below. The optical fibers 10 may form a ribbon core wire 15 (see FIG. 2 ) at a distance of, for example, 100 mm or more behind the boot 30. In this case, the optical fibers 10 are separated from one another between the ribbon core wire 15 and the boot 30. The reason why the optical fibers 10 are separated from one another in this manner is to enable chucking of each optical fiber 10 during rotational alignment and to absorb twisting during rotational alignment to prevent damage to the optical fibers 10.

[0025] The second accommodating hole 22 extends from the rear end face 20b into the ferrule 20 and includes a second opening 22a formed in the rear end face 20b. The second opening 22a has, for example, a rectangular shape when viewed from behind in the Z direction. The second accommodating hole 22 communicates with the multiple first accommodating holes 21 in the Z direction. The second accommodating hole 22 collectively accommodates the multiple optical fibers 10 inserted through the second opening 22a.

[0026] The boot 30 is made of flexible rubber and has a generally rectangular parallelepiped shape. The boot 30 has a front end face 30a, a rear end face 30b, and one or more insertion holes 31. The front end face 30a is located at the front end of the boot 30 in the Z direction. The rear end face 30b is located at the rear end of the boot 30 in the opposite direction to the Z direction. The insertion holes 31 penetrate between the front end face 30a and the rear end face 30b in the Z direction, and multiple optical fibers 10 are inserted into the insertion holes 31. If multiple optical fibers 10 are provided in multiple layers, multiple insertion holes 31 are provided. In this case, multiple optical fibers 10 from a corresponding layer are inserted into each insertion hole 31. The outer diameter of each of the multiple optical fibers 10 in the insertion holes 31 matches the center-to-center spacing of the multiple first receiving holes 21. The boot 30 is inserted into the second opening 22a and fits snugly into the second opening 22a. In FIG. 2, the boot 30 is shown in plan view rather than in cross section.

[0027] The first resin adhesive 41 is accommodated in the plurality of first receiving holes 21 and the second receiving holes 22 and fixes the plurality of optical fibers 10 to the ferrule 20. More specifically, the first resin adhesive 41 fixes the core portions 10b of the plurality of optical fibers 10 to the inner surface of each of the plurality of first receiving holes 21. The first resin adhesive 41 fixes the coating portions 10a of the plurality of optical fibers 10 to the inner surface of the second receiving hole 22. The first resin adhesive 41 is, for example, a thermosetting or ultraviolet-curing resin primarily composed of an epoxy-based material or a cyano-based material. When the first resin adhesive 41 is an epoxy-based adhesive, the first resin adhesive 41 may be an adhesive for optical components such as EPO-TEK (registered trademark) 353ND.

[0028] The second resin adhesive 42 adheres to the outer peripheral surfaces of at least two of the multiple optical fibers 10 at portions that pass through the insertion hole 31, and fixes these portions of the at least two optical fibers 10 together. The second resin adhesive 42 is interposed between the inner surface of the insertion hole 31 and the outer peripheral surfaces of the at least two optical fibers 10. In the illustrated example, the second resin adhesive 42 adheres to the outer peripheral surfaces of the multiple optical fibers 10 in each layer at portions that pass through the insertion hole 31, and fixes these portions of the multiple optical fibers 10 in each layer together. The second resin adhesive 42 is interposed between the inner surface of the insertion hole 31 and the outer peripheral surfaces of the multiple optical fibers 10 in each layer. In the illustrated example, the second resin adhesive 42 covers the entire multiple optical fibers 10 in each layer, but this example is not limited thereto. The second resin adhesive 42 may cover only a portion (for example, only the upper surface or only the lower surface) of the multiple optical fibers 10 in each layer. The second resin adhesive 42 may protrude rearward from the insertion hole 31. That is, the second resin adhesive 42 may have an exposed portion 42a exposed rearward from the insertion hole 31. The second resin adhesive 42 includes a constituent material different from the constituent material of the first resin adhesive 41. When the first resin adhesive 41 is a thermosetting type, the second resin adhesive 42 does not have to be a thermosetting type. The second resin adhesive 42 may be, for example, an ultraviolet curing type, a solvent volatilization type, or a moisture curing type. Specific examples of the second resin adhesive 42 include, for example, an epoxy acrylate resin, a urethane acrylate resin, an epoxy resin-based adhesive, or a silicone resin-based adhesive.

[0029] The tube 50 is a protective member in this embodiment. The tube 50 is hollow and cylindrical, and covers the multiple optical fibers 10 behind the boot 30. The exposed portion 42a of the second resin adhesive 42 may or may not be covered by the tube 50. The tube 50 is made of, for example, a flame-retardant material. Examples of flame-retardant materials include vinyl resins such as polyvinyl chloride (PVC) containing flame-retardant inorganic substances such as magnesium hydroxide or aluminum hydroxide, and polyolefin resins such as polyethylene (PE).

[0030] A method for manufacturing the multi-fiber optical connector 1A having the above configuration will be described. Fig. 4 is a flowchart showing an example of a method for manufacturing the multi-fiber optical connector 1A. This manufacturing method includes steps ST11 to ST16. In step ST11, a ferrule 20 having the above configuration is prepared. In step ST12, a first resin adhesive 41 is housed (injected) into the second housing hole 22 through the second opening 22a.

[0031] In step ST13, the plurality of optical fibers 10 separated from one another are inserted into the second receiving hole 22, and the plurality of optical fibers 10 are inserted into each of the plurality of first receiving holes 21. If the plurality of optical fibers 10 are optical fibers that require rotational alignment, such as multicore fibers or polarization-maintaining fibers, each optical fiber 10 is individually rotationally aligned at this timing. Step ST12 may be performed after step ST13. In step ST14, a second resin adhesive 42 is applied to the outer peripheral surfaces of portions of at least two of the plurality of optical fibers 10 that pass through the insertion hole 31 and then cured. This fixes the portions of the at least two optical fibers 10 together with the second resin adhesive 42.

[0032] In step ST15, the boot 30 is fitted into the second opening 22a, and the plurality of optical fibers 10 and the second resin adhesive 42 are placed in the insertion hole 31. In step ST16, the first resin adhesive 41 is hardened to fix the plurality of optical fibers 10 to the ferrule 20.

[0033] 5 is a flowchart showing an example of a manufacturing method for the multi-fiber optical connector 1A. This manufacturing method includes steps ST21 to ST26. The content of step ST21 is the same as step ST11 described above. In step ST22, a second resin adhesive 42 is applied to the outer peripheral surfaces of the portions of at least two of the multiple optical fibers 10 that pass through the insertion hole 31 and then cured. This causes the portions of the at least two optical fibers 10 to be fixed together by the second resin adhesive 42. The order of steps ST21 and ST22 is arbitrary. That is, step ST21 may be performed after step ST22.

[0034] In step ST23, the first resin adhesive 41 is accommodated (injected) into the second receiving hole 22 through the second opening 22a. In step ST24, the plurality of optical fibers 10 separated from one another are inserted into the second receiving hole 22, and the plurality of optical fibers 10 are inserted into each of the plurality of first receiving holes 21. If the plurality of optical fibers 10 are optical fibers that require rotational alignment, each optical fiber 10 is individually rotationally aligned at this timing. Step ST23 may be performed after step ST24. The contents of the subsequent steps ST25 and ST26 are the same as those of the above-described steps ST15 and ST16, respectively.

[0035] The effects achieved by the multi-fiber optical connector 1A and its manufacturing method according to the present embodiment, as described above, will now be described, along with the problems inherent in the prior art. In conventional multi-fiber optical connectors, the second resin adhesive 42 is not provided, which can lead to leakage of the first resin adhesive 41 from gaps between the insertion holes 31 and the optical fibers 10 to the outside of the ferrule 20. If the first resin adhesive 41 is a thermosetting type, the viscosity of the first resin adhesive 41 temporarily decreases during the temperature rise during curing, making the first resin adhesive 41 more likely to leak from gaps between the insertion holes 31 and the optical fibers 10. Additionally, if the optical fibers 10 are optical fibers that require rotational alignment, such as multicore fibers or polarization-maintaining fibers, the optical fibers 10 must be inserted into the ferrule 20 while separated from one another. In such cases, the gaps between the insertion holes 31 and the optical fibers 10 become larger, further increasing the likelihood of leakage of the first resin adhesive 41. Figure 6 illustrates the state in which the first resin adhesive 41 has leaked. If the first resin adhesive 41 leaks in this way, the flexibility of the first resin adhesive 41 after hardening is extremely low, and therefore, the bending stress of the optical fiber 10 cannot be absorbed, which may result in damage to the optical fiber 10. Furthermore, there is also the problem that the appearance of the multi-fiber optical connector is marred by the first resin adhesive 41 protruding outside the ferrule 20.

[0036] To address the above problem, in the multi-fiber optical connector 1A of this embodiment, a second resin adhesive 42 is interposed between the inner surface of the insertion hole 31 of the boot 30 and the outer peripheral surfaces of at least two optical fibers 10. This second resin adhesive 42 hardens before the first resin adhesive 41, thereby narrowing the gap between the insertion hole 31 and the multiple optical fibers 10 when the first resin adhesive 41 is hardened. Therefore, according to the multi-fiber optical connector 1A of this embodiment, the amount of first resin adhesive 41 leaking from the gap between the insertion hole 31 and the multiple optical fibers 10 can be reduced.

[0037] In the manufacturing method of this embodiment, in the sixth step of curing the first resin adhesive 41, the already cured second resin adhesive 42 is interposed between the inner surface of the insertion hole 31 of the boot 30 and the outer peripheral surfaces of at least two optical fibers 10. Therefore, the gap between the insertion hole 31 and the plurality of optical fibers 10 is narrowed when the first resin adhesive 41 is cured. This reduces the amount of first resin adhesive 41 leaking from the gap between the insertion hole 31 and the plurality of optical fibers 10.

[0038] As in the present embodiment, the plurality of optical fibers 10 may constitute a ribbon core wire 15 100 mm or more behind the boot 30, and may be separated from one another between the ribbon core wire 15 and the boot 30. For example, if the optical fibers 10 are of a type that requires rotational alignment, such as a multicore fiber or a polarization-maintaining fiber, the jacket of the ribbon core wire 15 is removed from the boot 30 over a long section, for example, 100 mm or more, to separate the plurality of optical fibers 10 from one another for rotational alignment of each optical fiber 10. In such a case, the presence of the second resin adhesive 42 is more effective.

[0039] As in this embodiment, the multi-fiber optical connector 1A may include a tube 50 that covers the plurality of optical fibers 10 behind the boot 30. In this case, the plurality of optical fibers 10 that have been separated from one another can be bundled together.

[0040] [First Modification] FIG. 7 is a cross-sectional view of a multi-fiber optical connector 1B according to a first modification of the embodiment, taken along a line corresponding to line II-II in FIG. 1 . FIG. 8 is a cross-sectional view of the multi-fiber optical connector 1B taken along line VIII-VIII in FIG. 7 . The multi-fiber optical connector 1B of this modification differs from the multi-fiber optical connector 1A of the embodiment in the outer diameter of each of the optical fibers 10. In this modification, the outer diameter of each of the optical fibers 10 in the insertion hole 31 (i.e., the outer diameter of the coating portion 10a) is smaller than the center-to-center spacing of the first receiving holes 21. Therefore, as shown in FIG. 8 , the resin coatings 12 of adjacent optical fibers 10 in each layer are spaced apart from each other. In one example, the outer diameter of the coating portion 10a is 200 μm. By reducing the outer diameter of the coating portion 10a, the optical fiber cable behind the connector can be made denser by increasing the number of fibers, or the cable outer diameter can be reduced while maintaining the same number of fibers, thereby saving space.

[0041] In this modification, the gap between the insertion hole 31 and the plurality of optical fibers 10 is wider than in the above embodiment. Therefore, without the second resin adhesive 42, the first resin adhesive 41 would be more likely to leak from the gap to the outside of the ferrule 20. By providing the second resin adhesive 42 in the gap as in this modification, the amount of first resin adhesive 41 leaking from the gap can be reduced.

[0042] [Second Modification] Fig. 9 is a side cross-sectional view of a multi-core optical connector 1C according to a second modification of the above embodiment, showing a cross section of the multi-core optical connector 1C along the YZ plane. As shown in Fig. 9, the multi-core optical connector 1C of this modification further includes one or more holding members 60 in addition to the configuration of the multi-core optical connector 1A of the above embodiment. In one example, the number of holding members 60 matches the number of layers of the multiple optical fibers 10. Therefore, when the number of layers of the multiple optical fibers 10 is two, as shown in Fig. 9, two holding members 60 are provided.

[0043] One or more holding members 60 are accommodated in the second receiving hole 22 of the ferrule 20 and are positioned between the boot 30 and the plurality of first receiving holes 21. When a plurality of holding members 60 are provided, the plurality of holding members 60 are arranged side by side in the Y direction, i.e., the thickness direction of the ferrule 20. Each holding member 60 holds the optical fiber 10 of a corresponding layer. Note that the holding member may hold multiple layers of optical fiber 10. In this case, the number of holding members does not need to match the number of layers of the multiple optical fibers 10. For example, in the example shown in FIG. 9 , instead of the two holding members 60, a single holding member that holds two layers of optical fiber 10 may be provided.

[0044] FIG. 10 is a perspective view showing a holding member 60A, which is an example of the holding member 60. The holding member 60A has a plurality of holding holes 61 that respectively hold a plurality of optical fibers 10. The plurality of holding holes 61 penetrate the holding member 60A along the Z direction. The plurality of holding holes 61 are aligned along the X direction. The inner diameter of each holding hole 61 is the same as or slightly larger than the outer diameter of the core portion 10b of each optical fiber 10. The rear end of each holding hole 61 tapers rearward. Each holding hole 61 holds the core portion 10b of each optical fiber 10 so that it can rotate freely around the central axis. The holding member 60A further has a surface 62 along the XZ plane behind the plurality of holding holes 61. The coating portion 10a of each optical fiber 10 is placed on the surface 62.

[0045] 11 is a perspective view showing a holding member 60B, which is an example of the holding member 60. This holding member 60B has a single hole 63 instead of the surface 62 of the holding member 60A described above. The hole 63 communicates with the multiple holding holes 61 and reaches the rear end surface of the holding member 60B. The cross section of the hole 63 along the XY plane is, for example, an ellipse extending in the X direction. The hole 63 collectively holds the coating portions 10a of the multiple optical fibers 10.

[0046] 12 is a perspective view showing a holding member 60C, which is an example of the holding member 60. This holding member 60C has multiple holes 64 instead of the single hole 63 of the above-described holding member 60B. Each of the multiple holes 64 communicates with each of the multiple holding holes 61 and reaches the rear end face of the holding member 60C. The cross section of each hole 64 along the XY plane is, for example, circular. Each hole 64 holds the coating portion 10a of each optical fiber 10.

[0047] FIG. 13 is a flowchart showing an example of a manufacturing method for a multi-fiber optical connector 1C according to this modification. This manufacturing method includes step ST13A in addition to the manufacturing method shown in FIG. 4 . Step ST13A is performed before step ST13. The order of step ST13A, ST11, and ST12 is arbitrary. That is, step ST13A may be performed before step ST12, or step ST13A may be performed before step ST11. In step ST13A, multiple optical fibers 10 that are separated from one another are gathered together using a holding member 60, thereby temporarily fixing the multiple optical fibers 10. At this time, the multiple optical fibers 10 are bonded to the holding member 60. The adhesive may be, for example, an ultraviolet-curing, solvent-evaporating, or moisture-curing resin. In step ST13, when the multiple optical fibers 10 are inserted into the second receiving hole 22, the holding member 60 is also inserted into the second receiving hole 22.

[0048] FIG. 14 is a flowchart showing an example of a manufacturing method for a multi-fiber optical connector 1C according to this modification. This manufacturing method includes step ST22A in addition to the manufacturing method shown in FIG. 5 . Step ST22A is performed before step ST22. Step ST21 and step ST22A may be performed in any order. That is, step ST22A may be performed before step ST21. In step ST22A, multiple optical fibers 10 that are separated from one another are gathered together using a holding member 60, thereby temporarily fixing the multiple optical fibers 10. At this time, the multiple optical fibers 10 are bonded to the holding member 60. The adhesive is, for example, an ultraviolet-curing, solvent-volatilizing, or moisture-curing resin. In step ST24, when the multiple optical fibers 10 are inserted into the second receiving hole 22, the holding member 60 is also inserted into the second receiving hole 22.

[0049] As in this modification, by temporarily fixing the plurality of optical fibers 10 using the holding member 60, the process of fixing the plurality of optical fibers 10 together with the second resin adhesive 42 can be facilitated.

[0050] DESCRIPTION OF SYMBOLS 1A, 1B, 1C... Multi-core optical connector 10... Optical fiber 10a... Coating portion 10b... Core wire portion 11... Glass fiber 12... Resin coating 15... Ribbon core wire 20... Ferrule 20a... Front end face 20b... Rear end face 21... First accommodating hole 21a... First opening 22... Second accommodating hole 22a... Second opening 30... Boot 30a... Front end face 30b... Rear end face 31... Insertion hole 41... First resin adhesive 42... Second resin adhesive 42a... Exposed portion 50... Tube 60, 60A, 60B, 60C... Holding member 61... Holding hole 62... Surface 63, 64... Hole

Claims

1. A multi-core optical connector comprising: a plurality of optical fibers; a ferrule having a front end face, a rear end face, and a plurality of first accommodating holes and a second accommodating hole, wherein each of the plurality of first accommodating holes includes a first opening formed in the front end face and accommodates a respective one of the plurality of optical fibers, and the second accommodating hole includes a second opening formed in the rear end face and communicates with the plurality of first accommodating holes, the second accommodating hole accommodating the plurality of optical fibers; a rubber boot having insertion holes into which the plurality of optical fibers are inserted and fitting into the second opening; a first resin adhesive that is accommodated in the plurality of first accommodating holes and the second accommodating hole and fixes the plurality of optical fibers to the ferrule; and a second resin adhesive that adheres to the outer peripheral surfaces of portions of at least two of the plurality of optical fibers that pass through the insertion holes and fixes the portions of the at least two optical fibers to each other, and is interposed between the inner surface of the insertion hole and the outer peripheral surfaces of the at least two optical fibers, wherein the plurality of optical fibers are separated from each other behind the second resin adhesive.

2. A multi-core optical connector according to claim 1, wherein the outer diameter of each of said plurality of optical fibers in said insertion hole is smaller than the center-to-center spacing of said plurality of first receiving holes.

3. A multi-core optical connector as described in claim 1 or claim 2, wherein the plurality of optical fibers form a ribbon core wire at a distance of 100 mm or more rearward from the boot, and are separated from each other between the ribbon core wire and the boot.

4. A multi-fiber optical connector according to any one of claims 1 to 3, further comprising a protective member that covers the plurality of optical fibers behind the boot.

5. A first step of preparing a ferrule having a front end face, a rear end face, a plurality of first receiving holes, and a second receiving hole, wherein each of the plurality of first receiving holes includes a first opening formed in the front end face, and the second receiving hole includes a second opening formed in the rear end face and communicates with the plurality of first receiving holes; a second step of accommodating a first resin adhesive in the second receiving holes, and inserting a plurality of optical fibers separated from one another into the second receiving holes and inserting each of the plurality of optical fibers into each of the plurality of first receiving holes; a third step of applying a second resin adhesive to the outer peripheral surfaces of portions of at least two of the plurality of optical fibers and hardening the second resin adhesive to fix the portions of the at least two optical fibers together; a fourth step of fitting a rubber boot having insertion holes into the second openings, and arranging the plurality of optical fibers and the second resin adhesive in the insertion holes; and a fifth step of hardening the first resin adhesive to fix the plurality of optical fibers to the ferrule. A method for manufacturing a multi-core optical connector, comprising:

6. A first step of preparing a ferrule having a front end face, a rear end face, a plurality of first receiving holes, and a second receiving hole, wherein each of the plurality of first receiving holes includes a first opening formed in the front end face, and the second receiving hole includes a second opening formed in the rear end face and communicates with the plurality of first receiving holes; a second step of accommodating a first resin adhesive in the second receiving holes, and applying and hardening a second resin adhesive to the outer peripheral surfaces of portions of at least two optical fibers among a plurality of optical fibers in a mutually separated state, thereby fixing the portions of the at least two optical fibers together with the second resin adhesive; a third step of inserting the plurality of optical fibers into the second receiving holes and inserting each of the plurality of optical fibers into each of the plurality of first receiving holes; a fourth step of fitting a rubber boot having insertion holes into the second openings, and arranging the plurality of optical fibers and the second resin adhesive in the insertion holes; and a fifth step of hardening the first resin adhesive to fix the plurality of optical fibers to the ferrule. A method for manufacturing a multi-core optical connector, comprising:

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