Method for manufacturing optical connector, optical fiber unit, and optical connector

Abstract

This method for manufacturing an optical connector comprises an arraying step for arraying a plurality of optical fibers having rotational directionality using an arraying member, a centering step for centering the plurality of optical fibers arrayed by the arraying member, a first bonding step for bonding the centered plurality of optical fibers to each other using a resin serving as a holding part, a removal step for removing the arraying member from the plurality of optical fibers, an insertion step for inserting the plurality of optical fibers securely bonded to each other by the holding part into fiber holes in a ferrule, and a second bonding step for bonding the ferrule and the plurality of optical fibers to each other using an adhesive.

Description

Method for manufacturing an optical connector, optical fiber unit, and optical connector

[0001] The present invention relates to a method for manufacturing an optical connector, an optical fiber unit, and an optical connector. This application claims priority based on Japanese Patent Application No. 2024-232443 filed in Japan on December 27, 2024, the content of which is incorporated herein by reference.

[0002] Patent Document 1 discloses an optical connection structure using a multi-core fiber having a plurality of cores provided in one optical fiber. In the manufacture of such an optical connection structure, in order to adjust the positions of the cores, the multi-core fiber is rotated (centering) while observing the end face of the multi-core fiber using a camera or the like. Further, not only for multi-core fibers, but also when using a PANDA (Polarization-maintaining AND Absorption-reducing) type polarization-maintaining optical fiber or the like, centering is performed. Hereinafter, an optical fiber that requires such centering is referred to as an "optical fiber having rotational directivity".

[0003] Japanese Patent Application Laid-Open No. 2013-125195

[0004] When attaching an optical fiber having rotational directivity to an optical connector, centering may be performed in advance before inserting the optical fiber into the ferrule. Conventionally, a method has been devised in which centering is performed using an alignment member having a V-groove or the like, and the entire alignment member is inserted into the ferrule. However, according to this method, it is necessary to make the size of the ferrule larger than that of the alignment member, and it has been difficult to miniaturize the optical connector.

[0005] The present invention has been made in consideration of such circumstances, and an object thereof is to provide a method for manufacturing an optical connector, an optical fiber unit, and an optical connector that can miniaturize the optical connector with respect to an optical connector using an optical fiber having rotational directivity.

[0006] To solve the above problems, a method for manufacturing an optical connector according to embodiment 1 of the present invention comprises: an alignment step of aligning a plurality of optical fibers having a rotational direction using an alignment member; a centering step of centering the plurality of optical fibers aligned by the alignment member; a first bonding step of bonding the centered plurality of optical fibers to each other with a resin that serves as a holding part; a removal step of removing the alignment member from the plurality of optical fibers; an insertion step of inserting the plurality of optical fibers, which are bonded and fixed to each other by the holding part, into the fiber hole of a ferrule; and a second bonding step of bonding the ferrule and the plurality of optical fibers with an adhesive.

[0007] Aspect 2 of the present invention is a method for manufacturing an optical connector according to aspect 1, wherein in the first bonding step, the resin that will form the holding portion is positioned at a distance in the longitudinal direction from the alignment member.

[0008] An optical fiber unit according to embodiment 3 of the present invention comprises a plurality of optical fibers having a rotational directionality and a holding portion that holds the angle of the plurality of optical fibers, wherein the holding portion is made of only one type of material.

[0009] A fourth aspect of the present invention is an optical fiber unit according to the third aspect, wherein the Young's modulus of the holding portion is 10 MPa or more.

[0010] A fifth aspect of the present invention is an optical fiber unit according to aspect 3 or aspect 4, wherein the Shore D hardness of the holding portion is 75 or higher.

[0011] Aspect 6 of the present invention is an optical fiber unit according to any of aspects 3 to 5, wherein a filler is added to the holding portion.

[0012] An optical connector according to embodiment 7 of the present invention comprises an optical fiber unit according to any of embodiments 3 to 6, a ferrule having fiber holes into which the plurality of optical fibers are inserted, and an adhesive for fixing the ferrule and the optical fiber unit.

[0013] Aspect 8 of the present invention is an optical connector according to aspect 7, wherein the holding portion and the adhesive are made of different materials.

[0014] According to the above aspects of the present invention, with respect to optical connectors using optical fibers having rotational directionality, it is possible to provide a method for manufacturing an optical connector, an optical fiber unit, and an optical connector that can be miniaturized.

[0015] This is a perspective view of the optical connector according to this embodiment. This is a perspective view of the optical fiber unit shown in Figure 1, with the optical fiber unit extracted. This is a diagram illustrating the manufacturing method of the optical fiber unit according to this embodiment. This is a perspective view showing a first modified example of the optical fiber unit according to this embodiment. This is a perspective view showing a second modified example of the optical fiber unit according to this embodiment. This is a perspective view showing a third modified example of the optical fiber unit according to this embodiment.

[0016] The optical fiber unit, optical connector, and method for manufacturing the optical connector of this embodiment will be described below with reference to the drawings. As shown in Figure 1, the optical connector 1 comprises a plurality of optical fiber units 2 and a ferrule 10. In the example shown in Figure 1, there are two optical fiber units 2, but the number of optical fiber units 2 may be one or three or more.

[0017] As shown in Figure 2, the optical fiber unit 2 has a plurality of optical fibers 3 and a holding part 4. As will be described in detail later, the plurality of optical fibers 3 are maintained in an aligned state by the holding part 4. Each optical fiber 3 is inserted into a plurality of fiber holes 11 (see Figure 1) formed in the ferrule 10. The ferrule 10 also has a connecting end face 12 through which the fiber holes 11 open. When another connector or the like abuts against the connecting end face 12, the plurality of optical fibers 3 and the optical fibers of the other connector are optically connected. Here, the optical connector 1 may be referred to as the first connector, and the other connector may be referred to as the second connector.

[0018] (Direction Definitions) In this embodiment, the direction in which the fiber hole 11 extends is referred to as the longitudinal direction Z. In the longitudinal direction Z, the side where the connection end face 12 is located (+Z side) is referred to as the front. The side opposite to the side where the connection end face 12 is located (+Z side) (-Z side) is referred to as the rear. In one optical fiber unit 2, the direction in which multiple optical fibers 3 are arranged is referred to as the parallel direction X. The parallel direction X is perpendicular to the longitudinal direction Z. The direction perpendicular to both the parallel direction X and the longitudinal direction Z is referred to as the orthogonal direction Y.

[0019] As shown in Figure 1, the ferrule 10 has a rear end face 13, an insertion opening 14, and a filling hole 15. The rear end face 13 is the end face opposite to the connection end face 12. The rear end face 13 faces rearward (-Z side). The insertion opening 14 opens to the rear end face 13. The insertion opening 14 communicates with the fiber hole 11. The optical fiber unit 2 is inserted into the ferrule 10 through the insertion opening 14. The filling hole 15 opens in the orthogonal direction Y. The filling hole 15 communicates with the fiber hole 11 and the insertion opening 14. The filling hole 15 is used when filling the ferrule 10 with adhesive 20. However, the adhesive 20 may be filled into the ferrule 10 through the insertion opening 14. Alternatively, the adhesive 20 may be filled into the fiber hole 11 from the connection end face 12 side. In these cases, it is not essential that the ferrule 10 has a filling hole 15.

[0020] In this embodiment, two optical fiber units 2 are inserted into the ferrule 10 in an orthogonal direction Y. Corresponding to the optical fiber units 2 aligned in the orthogonal direction Y, the ferrule 10 has a plurality of fiber holes 11 formed in two rows in the orthogonal direction Y. The plurality of fiber holes 11 included in each of the two rows are aligned in the parallel direction X.

[0021] As shown in Figure 2, each optical fiber 3 has a bare portion 3a and a coating 3b. The bare portion 3a includes a core, cladding, etc. The bare portion 3a is formed of, for example, quartz glass. The coating 3b covers the bare portion 3a. The coating 3b is formed of, for example, resin. At the tip of the optical fiber 3, the coating 3b is removed and the bare portion 3a is exposed. The exposed bare portion 3a is inserted into the fiber hole 11 of the ferrule 10.

[0022] The optical fiber 3 in this embodiment has rotational directionality. Rotational directionality is a property in which the connection state between the optical fiber 3 and other optical fibers changes depending on the angle when the optical fiber 3 is rotated. In an optical fiber 3 having rotational directionality, a centering process is required to stabilize the connection state with other optical fibers. The centering process is a process of adjusting the angle of rotation of the optical fiber 3 to satisfy predetermined performance. Here, the optical fiber 3 may be referred to as the first fiber, and the other optical fibers may be referred to as the second optical fiber.

[0023] Examples of optical fibers 3 having rotational directionality include multicore fibers and polarization-maintaining optical fibers. A multicore fiber has a structure in which multiple cores are arranged in a single cladding. For example, the number of cores may be four. Polarization-maintaining optical fibers may be PANDA (Polarization-maintaining AND Absorption-reducing) type, bowtie type, and elliptical cladding type, etc. However, this embodiment is not limited to the above examples, and any optical fiber 3 having rotational directionality can be suitably applied.

[0024] The holding part 4 has the function of maintaining the aligned state of the multiple optical fibers 3. More specifically, the holding part 4 adhesively fixes the multiple optical fibers 3 to each other. Therefore, the independent rotation of each optical fiber 3 is restricted. In addition, the multiple optical fibers 3 are fixed by the holding part 4 in a state where they are arranged in parallel direction X. Therefore, when the multiple optical fibers 3 together with the holding part 4 are inserted into the ferrule 10, the angle of each optical fiber 3 is determined with respect to the parallel direction X. In the ferrule 10, the multiple fiber holes 11 are also arranged in parallel direction X. Therefore, as a result, the angle of the multiple optical fibers 3 with respect to the ferrule 10 is determined. In other words, the optical fiber 3 can be maintained in an aligned state in the state of the optical connector 1.

[0025] As described above, the holding portion 4 has the function of maintaining the aligned state of the optical fiber 3. In the example shown in Figure 2, the holding portion 4 is arranged across the bare portion 3a and the coating 3b. As will be described in detail later, the length range of the region in which the holding portion 4 is formed and the shape of the holding portion 4 are not limited to Figure 2 and can be changed. The holding portion 4 has the strength to maintain the angle of the optical fiber 3. For example, the Young's modulus of the holding portion 4 may be 10 MPa or more. Also, the Shore D hardness of the holding portion 4 may be 75 or more.

[0026] It has been experimentally proven that the optical fiber 3 can maintain its centered state if the Young's modulus of the holding part 4 is 10 MPa or higher, or if its Shore D hardness is 75 or higher. However, as long as the optical fiber 3 can maintain its centered state, the Young's modulus of the holding part 4 may be less than 10 MPa, and its Shore D hardness may be less than 75. Specific materials for the holding part 4 that satisfy the above conditions include, for example, acrylic or epoxy UV-curing resins.

[0027] Furthermore, a filler may be added to the holding part 4. Specific examples of fillers include fine fibrous or spherical glass. By adding a filler to the holding part 4, for example, the viscosity of the resin forming the holding part 4 before it hardens can be adjusted. By adjusting the viscosity, the shape and arrangement of the holding part 4 after hardening can be stabilized. Additionally, by adding a filler, for example, the coefficient of linear expansion of the holding part 4 can be adjusted. By adjusting the coefficient of linear expansion of the holding part 4 to be closer to that of the optical fiber 3, differences in expansion or contraction between the holding part 4 and the optical fiber 3 due to temperature changes can be suppressed. Therefore, it is possible to suppress the holding part 4 from peeling off from the optical fiber 3 or the holding part 4 generating lateral pressure on the optical fiber 3.

[0028] The adhesive 20 serves to bond and fix the optical fiber unit 2 and the ferrule 10. In Figure 1, the adhesive 20 is filled into the filling hole 15, but for example, the adhesive 20 may be filled only inside the fiber hole 11. In this case as well, it is possible to bond and fix the optical fiber unit 2 and the ferrule 10. Examples of materials for the adhesive 20 include epoxy-based heat-curing resins.

[0029] Next, a method for manufacturing the optical connector 1 having the above configuration will be described. Note that the following manufacturing method is an example and can be modified as appropriate.

[0030] The manufacturing method of this embodiment includes an alignment step, a centering step, a first bonding step, a removal step, an insertion step, and a second bonding step. In the alignment step, a plurality of optical fibers 3 are arranged in a line using an alignment member 6, for example, as shown in Figure 3. The alignment member 6 is made of glass, for example. The alignment member 6 has a plurality of V-shaped grooves or a plurality of holes for aligning the plurality of optical fibers 3. If the alignment member 6 has V-shaped grooves, for example, after setting the optical fibers 3 in the V-shaped grooves, the optical fibers 3 may be temporarily fixed to the alignment member 6 with clamps or the like. This prevents the optical fibers 3 from floating up from the V-shaped grooves.

[0031] In the alignment process, the optical fibers 3 are aligned by the alignment member 6, and then aligned. For example, the optical fibers 3 may be rotated while observing the end face of the optical fiber 3 with a camera or the like, and the rotation of the optical fiber 3 may be stopped at a predetermined position. Alternatively, the optical fibers 3 may be aligned by other methods.

[0032] In the first bonding step, with each optical fiber 3 aligned, a resin that will form the holding portion 4 is applied to the optical fibers 3 and cured. At this time, as shown in Figure 3, it is preferable that the resin that will form the holding portion 4 is applied at a position separated from the alignment member 6 in the longitudinal direction. This prevents multiple optical fibers 3 from being mistakenly bonded to the alignment member 6. By applying the resin that will form the holding portion 4 between multiple optical fibers 3 and curing it, the aligned state of the multiple optical fibers 3 is maintained. The curing method is not limited, but for example, if the holding portion 4 is a UV-curable resin, UV light is irradiated onto the resin that will form the holding portion 4.

[0033] In the removal process, the alignment members 6 are removed from the multiple optical fibers 3. For example, if clamps are used in the alignment process, the locks provided by the clamps are released. By removing the alignment members 6, an optical fiber unit 2 is obtained in which the optical fibers 3 are aligned, as shown in Figure 2.

[0034] In the insertion process, the optical fiber unit 2 obtained as described above is inserted into the insertion opening 14 of the ferrule 10. Also, the bare portion 3a of each optical fiber 3 is inserted into the fiber hole 11. At this time, as shown in Figure 1, a part of the holding portion 4 may extend behind the rear end face 13 (towards the -Z side). Alternatively, the entire holding portion 4 may be housed inside the insertion opening 14.

[0035] In the second bonding step, the optical fiber unit 2 is bonded and fixed to the ferrule 10 using adhesive 20. At this time, as shown in Figure 1, the uncured adhesive 20 may be filled into the filling hole 15 and the adhesive 20 may be cured. The uncured adhesive 20 may be introduced into the fiber hole 11 by capillary action. Alternatively, the uncured adhesive 20 may be introduced from the connection end face 12 or the rear end face 13. The curing method is not limited, but for example, if the adhesive 20 is a heat-curing resin, the entire optical connector 1 may be heated.

[0036] Through the above process, the aligned optical fiber 3 is fixed to the ferrule 10, and the optical connector 1 is completed. In this manufacturing method, the alignment member 6 has a reference surface for alignment (for example, the bottom surface or the side surface), but the holding part 4 does not have a reference surface for alignment. In other words, the completed optical connector 1 does not have a reference surface for the alignment of the optical fiber 3. The holding part 4 only needs to have the function of holding the optical fiber 3 in an aligned state, so the volume of the holding part 4 can be reduced.

[0037] The shape and position of the retaining portion 4 can be changed. For example, as shown in Figure 4, the retaining portion 4 may be provided only on the bare portion 3a. Alternatively, as shown in Figure 5, the retaining portion 4 may be provided only in the gaps between the bare portions 3a. Alternatively, as shown in Figure 6, the retaining portion 4 may be provided only on the covering 3b.

[0038] As described above, the manufacturing method of the optical connector 1 of this embodiment includes an alignment step of aligning a plurality of optical fibers 3 having a rotational direction using an alignment member 6, a centering step of centering the plurality of optical fibers 3 aligned by the alignment member 6, a first bonding step of bonding the centered plurality of optical fibers 3 to each other with a resin that forms a holding part 4, a removal step of removing the alignment member 6 from the plurality of optical fibers 3, an insertion step of inserting the plurality of optical fibers 3, which are bonded and fixed to each other by the holding part 4, into the fiber hole 11 of the ferrule 10, and a second bonding step of bonding the ferrule 10 and the plurality of optical fibers 3 with an adhesive 20.

[0039] According to the manufacturing method of this embodiment, the alignment member 6 used for centering is not included in the optical connector 1. Therefore, it is not necessary to make the ferrule 10 larger than the alignment member 6, and the optical connector 1 can be made smaller overall.

[0040] Furthermore, in the first bonding step, the resin that forms the holding portion 4 is positioned at a distance in the longitudinal direction Z from the alignment member 6. This prevents the resin that forms the holding portion 4 from getting between the alignment member 6 and the optical fiber 3, thus preventing the alignment member 6 and the optical fiber 3 from being mistakenly bonded together. Therefore, in the removal step, the alignment member 6 can be easily removed from the optical fiber 3.

[0041] Furthermore, the optical fiber unit 2 of this embodiment includes a plurality of optical fibers 3 having a rotational directionality, and a holding part 4 that holds the angles of the plurality of optical fibers 3, and the holding part 4 is made of only one type of material. The optical connector 1 of this embodiment includes the optical fiber unit 2, a ferrule 10 having a fiber hole 11 into which the plurality of optical fibers 3 are inserted, and an adhesive 20 that fixes the ferrule 10 and the optical fiber unit 2. Conventionally, the angles of the optical fibers 3 were held using two types of materials: a member corresponding to the alignment member 6 (for example, made of glass) and an adhesive. In contrast, by holding the angles of the optical fibers 3 with a holding part 4 made of only one type of material, the optical connector 1 can be miniaturized.

[0042] Furthermore, the materials of the retaining part 4 and the adhesive 20 may be different. In this case, for example, the material of the retaining part 4 may be a material that is necessary and sufficient to maintain the aligned state of the optical fiber 3. The material of the adhesive 20 may be a material that is necessary and sufficient to fix the ferrule 10 and the optical fiber unit 2. In other words, appropriate materials can be used for the retaining part 4 and the adhesive 20, depending on their respective roles.

[0043] Furthermore, the Young's modulus of the holding portion 4 may be 10 MPa or higher. Also, the Shore D hardness of the holding portion 4 may be 75 or higher. In these cases, the holding portion 4 can maintain the aligned state of the optical fiber 3.

[0044] Further, a filler may be added to the holding portion 4. By adding the filler, the viscosity and linear expansion coefficient of the resin that becomes the holding portion 4 before curing may be adjusted.

[0045] Note that the technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

[0046] For example, the optical connector 1 may have a positioning pin or the like for aligning with another optical connector. Further, the shape of the ferrule 10 in FIG. 1 is merely an example and may be changed.

[0047] Also, within the scope not departing from the gist of the present invention, it is possible to appropriately replace the components in the above-described embodiment with well-known components, and the above-described embodiment and modified examples may be appropriately combined.

[0048] 1... optical connector, 2... optical fiber unit, 3... optical fiber, 4... holding portion, 6... alignment member, 10... ferrule, 11... fiber hole, 20... adhesive, Z... longitudinal direction

Claims

1. A method for manufacturing an optical connector, comprising: an alignment step of aligning a plurality of optical fibers having a rotational direction using an alignment member; an alignment step of centering the plurality of optical fibers aligned by the alignment member; a first bonding step of bonding the centered plurality of optical fibers to each other with a resin that serves as a holding part; a removal step of removing the alignment member from the plurality of optical fibers; an insertion step of inserting the plurality of optical fibers, which are bonded and fixed to each other by the holding part, into the fiber hole of a ferrule; and a second bonding step of bonding the ferrule and the plurality of optical fibers with an adhesive.

2. In the first bonding step, the resin that will form the holding portion is positioned at a distance in the longitudinal direction from the alignment member, the method for manufacturing an optical connector according to claim 1.

3. An optical fiber unit comprising: a plurality of optical fibers having a rotational directionality; and a holding part that holds the angle of the plurality of optical fibers, wherein the holding part is made of only one type of material.

4. The optical fiber unit according to claim 3, wherein the Young's modulus of the holding portion is 10 MPa or more.

5. The optical fiber unit according to claim 3, wherein the Shore D hardness of the holding portion is 75 or higher.

6. The optical fiber unit according to claim 3, wherein a filler is added to the holding portion.

7. An optical connector comprising: an optical fiber unit according to any one of claims 3 to 6; a ferrule having a fiber hole into which the plurality of optical fibers are inserted; and an adhesive for fixing the ferrule and the optical fiber unit.

8. The optical connector according to claim 7, wherein the holding portion and the adhesive are made of different materials.

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