Ferrule, optical connector, and method for manufacturing optical connector

Abstract

This ferrule comprises: a ferrule main body having a ferrule front end and a ferrule back end; an introduction hole provided in the ferrule main body; and a fiber insertion hole configured to be able to hold tip portions of a plurality of optical fibers. The fiber insertion hole has a taper portion and a fiber holding portion. The taper portion includes a taper front end and a taper back end, and extends from the taper back end to the taper front end such that the inner diameter of the taper portion at the taper front end is smaller than the inner diameter of the taper portion at the taper back end. The angle between the center line axis of each of the plurality of fiber insertion holes and a taper straight line connecting the taper front end and the taper back end of the taper portion in a cross section along the center line axis is 1-14 degrees.

Description

[Technical Field]

[0001] The present disclosure relates to a ferrule, an optical connector, and a method for manufacturing an optical connector. This application claims priority from Japanese Application No. 2023-025311, filed February 21, 2023, and incorporates by reference all of the contents of said Japanese application. [Background technology]

[0002] Patent Document 1 discloses a ferrule having a fiber insertion hole (micropore) into which an optical fiber is inserted. In this ferrule, the fiber insertion hole extends along the longitudinal direction of the ferrule to the front end of the ferrule. A part of the inner surface of the fiber insertion hole is formed so that the inner diameter decreases as it approaches the front end of the ferrule. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2007-163626 Summary of the Invention [Means for solving the problem]

[0004] A ferrule according to an embodiment of the present disclosure includes a ferrule body, an introduction hole, and a plurality of fiber insertion holes. The ferrule body has a ferrule front end and a ferrule rear end opposite the ferrule front end in a first direction. The introduction hole is provided in the ferrule body from the ferrule rear end toward the ferrule front end. The plurality of fiber insertion holes are configured to be able to hold the tip ends of a plurality of optical fibers, respectively, and extend along the first direction from a portion of the introduction hole near the ferrule front end to the ferrule front end. Each of the plurality of fiber insertion holes has a tapered portion including a tapered shape, and a fiber holding portion that communicates with the tapered portion near the ferrule front end and extends along the first direction to the ferrule front end. The tapered portion is ,before end, reach Before End and opposite side in the first direction After The tapered part includes the end. ,before Inner diameter of tapered part at end After so that the inner diameter is smaller than the tapered part at the end ,rear Edge Before The center line axis of each of the plurality of fiber insertion holes and the tapered portion in the cross section along the center line axis are Before end and after Tie the ends together Datenao The angle between the lines is between 1 degree and 14 degrees. [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 is a perspective view showing an optical connector according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II shown in FIG. [Figure 3] FIG. 3 is a cross-sectional view showing a ferrule in the optical connector of FIG. [Figure 4] FIG. 4 is a diagram showing the tip face of the optical fiber in the optical connector of FIG. [Figure 5] FIG. 5 is a schematic diagram showing a fiber insertion hole in the ferrule of FIG. [Figure 6] FIG. 6 is a flowchart showing a method for manufacturing an optical connector according to one embodiment. [Figure 7] FIG. 7 is a schematic diagram showing a fiber insertion hole in a conventional ferrule. [Figure 8] FIG. 8 is a schematic diagram showing a case where an optical fiber is inserted into a fiber insertion hole in a conventional ferrule. [Figure 9] FIG. 9 is a schematic diagram showing axial misalignment caused by rotation of an optical fiber when the optical fiber is inserted into a fiber insertion hole in a conventional ferrule. [Figure 10] FIG. 10 is a schematic diagram showing a fiber insertion hole in a ferrule according to a modified example. [Figure 11] FIG. 11 is a schematic diagram showing a fiber insertion hole in a ferrule according to a modified example. [Figure 12] FIG. 12 is a schematic diagram showing a fiber insertion hole in a ferrule according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0006] [Problem to be solved by this disclosure] In the ferrule described in Patent Document 1, when an optical fiber is inserted into a fiber insertion hole, the optical fiber may come into contact with the inner surface of the fiber insertion hole where the inner diameter decreases and rotate, causing a circumferential shift (axial misalignment) of the optical fiber. Specifically, when the optical fiber is inserted into the fiber insertion hole while coming into contact with the tapered inner surface, the optical fiber rotates due to the frictional force it receives from the inner surface of the fiber insertion hole, causing an axial misalignment. Therefore, if an optical fiber that requires rotational alignment (e.g., a multi-core fiber) is inserted into such a ferrule and an axial misalignment occurs, the optical coupling efficiency between the misaligned optical fiber and optical fibers held in other ferrules will decrease.

[0007] [Effects of this disclosure] According to the present disclosure, when an optical fiber that requires rotational alignment is inserted into a ferrule, it is possible to suppress a decrease in optical coupling efficiency between the optical fiber held in the ferrule and an optical fiber held in another ferrule.

[0008] [Description of the embodiments of the present disclosure] First, the contents of the embodiments of the present disclosure will be listed and described. [1] A ferrule according to one embodiment includes a ferrule body, an introduction hole, and a plurality of fiber insertion holes. The ferrule body has a ferrule front end and a ferrule rear end opposite the ferrule front end in a first direction. The introduction hole is provided in the ferrule body from the ferrule rear end toward the ferrule front end. The plurality of fiber insertion holes are configured to be able to hold the tip ends of a plurality of optical fibers, respectively, and extend along the first direction from a portion of the introduction hole near the ferrule front end to the ferrule front end. Each of the plurality of fiber insertion holes has a tapered portion including a tapered shape, and a fiber holding portion that communicates with the tapered portion near the ferrule front end and extends along the first direction to the ferrule front end. The tapered portion is ,before end, reach Before End and opposite side in the first direction After The tapered part includes the end. ,before Inner diameter of tapered part at end After so that the inner diameter is smaller than the tapered part at the end ,rear Edge Before The center line axis of each of the plurality of fiber insertion holes and the tapered portion in the cross section along the center line axis are Before end and after Tie the ends together Datenao The angle between the lines is between 1 degree and 14 degrees.

[0009] In this ferrule, the center line axes of the plurality of fiber insertion holes and the tapered portions in the cross section along the center line axes are Before end and after Tie the ends together DatenaoThe angle between the optical fiber and the line is between 1 degree and 14 degrees, and the shape of the tapered portion is a gentle taper. This gentler taper configuration than conventional ferrules reduces the frictional force that the optical fiber receives from the inner surface of the tapered portion when it is inserted into the fiber insertion hole and comes into contact with the inner surface of the tapered portion, compared to conventional ferrules. This prevents the optical fiber from rotating and becoming misaligned when it is inserted into the fiber insertion hole. As a result, when an optical fiber that requires rotational alignment is inserted into a ferrule, the axial misalignment of the optical fiber is suppressed, thereby preventing a decrease in optical coupling efficiency between the optical fiber and optical fibers held in other ferrules.

[0010] [2] In one embodiment, in the above [1], in a cross section along the center line axis of the fiber insertion hole, ,straight The line may coincide with the inner surface of the tapered portion. In this case, because the inner surface of the tapered portion is flat, the optical fiber in contact with the inner surface of the tapered portion is further prevented from rotating and becoming misaligned. As a result, when an optical fiber requiring rotational alignment is inserted into a ferrule, the misalignment of the optical fiber is further suppressed, thereby further suppressing a decrease in optical coupling efficiency between the optical fiber and optical fibers held in other ferrules.

[0011] [3] In one embodiment, in the above [1], in a cross section along the centerline axis, the angle between the tangent at the contact point on the inner surface of the tapered portion and the centerline axis of the fiber insertion hole is Tapered section It may decrease as the contact point approaches the front end. ,before As the fiber approaches the end, the inner surface of the tapered section becomes more gradual. ,before The frictional force received from the inner surface of the tapered portion near the end can be further reduced. ,rear The inner diameter of the tapered portion at the end can be made larger, so that the optical fiber can be inserted into the fiber insertion hole more easily. AfterThe tapered portion is formed on the ferrule so that the optical fiber is prevented from coming into contact with the inner surface of the tapered portion near the end of the optical fiber. As a result, when the optical fiber is inserted into the fiber insertion hole, the optical fiber is prevented from coming into contact with the inner surface of the tapered portion, rotating and causing axial misalignment. As a result, when an optical fiber that requires rotational alignment is inserted into a ferrule, axial misalignment of the optical fiber is further suppressed, thereby further suppressing a decrease in optical coupling efficiency between the optical fiber and optical fibers held in other ferrules.

[0012] [4] As an embodiment, in any one of the above [1] to [3], each of the plurality of fiber insertion holes may further have an introduction portion, the introduction portion extending from the introduction hole along the first direction, Tapered section The introduction portion communicates with the tapered portion at its rear end. The introduction portion may have a constant inner diameter. In this case, the introduction portion that initially receives the optical fiber introduced from the introduction hole has a constant inner diameter, so the optical fiber can be inserted into the fiber insertion hole while preventing the optical fiber from contacting the inner surface of the introduction portion. As a result, rotation of the optical fiber and axial misalignment when the optical fiber is inserted into the fiber insertion hole are further prevented.

[0013] [5] As one embodiment, in any of the above [1] to [4], the ratio of the length of the tapered portion to the length of each of the plurality of fiber insertion holes in the first direction may be 1 / 5 or more and 3 / 4 or less. In this case, since the length ratio is 3 / 4 or less, it is possible to make the fiber holding portion of the fiber insertion hole sufficiently long in the first direction. This makes it possible for each fiber holding portion to stably support each optical fiber. Furthermore, since the length ratio is 1 / 5 or more, it is possible to make the tapered portion sufficiently long in the first direction. This ,rear Since the inner diameter of the tapered portion at the end can be made sufficiently large, the optical fiber can be inserted into the fiber insertion hole without causing a problem. After This further prevents the shaft from coming into contact with the inner surface of the tapered portion near the end, causing rotation and axial misalignment.

[0014] [6] In one embodiment, in any one of the above [1] to [5], the center line axis of each of the plurality of fiber insertion holes and the cross section along the center line axis are Direct The angle between the line may be 5 degrees or more and 10 degrees or less. In this case, rotation of the optical fiber and axial misalignment caused by the rotation of the optical fiber when the optical fiber is inserted into the fiber insertion hole is further suppressed. As a result, when an optical fiber that requires rotational alignment is inserted into a ferrule, axial misalignment of the optical fiber is further suppressed, thereby further suppressing a decrease in optical coupling efficiency between the optical fiber and optical fibers held in other ferrules.

[0015] [7] An optical connector according to one embodiment includes the ferrule according to any one of [1] to [6] above and a plurality of optical fibers. The plurality of optical fibers are held in a plurality of fiber insertion holes, respectively. Each of the plurality of optical fibers is one of a multi-core optical fiber, a polarization-maintaining fiber, and a bundle fiber. In this optical connector, the plurality of optical fibers are fixed to the ferrule described above. With this configuration, rotation and axial misalignment of the optical fiber when inserted into the fiber insertion hole are suppressed. Here, the optical fiber is one of a multi-core optical fiber, a polarization-maintaining fiber, and a bundle fiber, and is a fiber that requires rotational alignment. Therefore, axial misalignment of the optical fiber when inserted into the ferrule is further suppressed, thereby further suppressing a decrease in optical coupling efficiency between the optical fiber and optical fibers held in other ferrules.

[0016] [8] A method for manufacturing an optical connector according to one embodiment includes the steps of preparing a ferrule according to any one of [1] to [6] above, preparing a plurality of optical fibers, and inserting corresponding ones of the plurality of optical fibers into the plurality of fiber insertion holes. Light and inserting the fiber. Providing a plurality of optical fibers,Each of the multiple optical fibers is one of a multi-core optical fiber, a polarization-maintaining fiber, and a bundle fiber. In this optical connector manufacturing method, a ferrule having a fiber insertion hole with a gently tapered shape is used, and the optical fiber is inserted into such a fiber insertion hole. This further suppresses the optical fiber from rotating and causing axial misalignment. Here, the optical fiber is one of a multi-core optical fiber, a polarization-maintaining fiber, and a bundle fiber, and is a fiber that requires rotational alignment. Therefore, by further suppressing axial misalignment of the optical fiber when inserting it into the ferrule, an optical connector can be realized that further suppresses a decrease in optical coupling efficiency between the optical fiber and optical fibers held in other ferrules.

[0017] [Details of the embodiments of the present disclosure] Specific examples of ferrules, optical connectors, and methods for manufacturing optical connectors according to embodiments of the present disclosure will be described below with reference to the drawings. In the following description, identical elements or elements having identical functions will be designated by the same reference numerals, and duplicated descriptions will be omitted. Note that 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 equivalent to the claims.

[0018] Fig. 1 is a perspective view showing an optical connector according to this embodiment. Fig. 2 is a cross-sectional view taken along line II-II shown in Fig. 1. Fig. 3 is a cross-sectional view showing a ferrule of the optical connector of Fig. 2. As shown in Figs. 1 and 2, the optical connector 1 includes a plurality of holding components 10, a plurality of multi-core optical fibers 20 (hereinafter also referred to as "MCFs 20"), and a ferrule 30. Hereinafter, the width direction of the optical connector 1 is defined as the X direction, the height direction of the optical connector 1 is defined as the Y direction, and the longitudinal direction of the optical connector 1, which is a direction intersecting the X direction and the Y direction, is defined as the Z direction (first direction).

[0019] As shown in FIG. 2, the holding component 10 has a rectangular parallelepiped shape. The cross section of the holding component 10 intersecting the X direction is rectangular. The holding component 10 is made of, for example, quartz glass, a metal material, or a resin material. The holding component 10 is configured to hold a plurality of MCFs 20. For example, the holding component 10 has a plurality of V-grooves extending in the Z direction. The V-grooves are aligned along the X direction and each hold a plurality of MCFs 20. As an example, a plurality of MCFs 20 are placed and fixed in each of the V-grooves.

[0020] The holding parts 10 (for example, two) are aligned in the Y direction. In the example shown in FIG. 2, the two holding parts 10 are aligned in the Y direction. Each holding part 10 holds 16 MCFs 20 aligned in the X direction. Y direction In this inverted state, the holding parts 10 are fixed to each other.

[0021] Each MCF20 is line axis 4 is a diagram showing the tip surface of the MCF 20. For example, each MCF 20 has at least two cores in the center. line axis The MCF 20 has a plurality of cores 20a arranged at equal intervals around the ferrule 30. Each MCF 20 has a cladding 20b covering the plurality of cores 20a. As shown in FIG. 2, each MCF 20 has a tip portion 21 including a tip face 20c, a coated portion 22, and a coated-removed portion 23. The plurality of MCFs 20 are held in the plurality of fiber insertion holes 40, respectively. The plurality of MCFs 20 are fixed to the ferrule 30 with an adhesive.

[0022] The coating portion 22 has a plurality of cores 20a, a cladding 20b covering the cores 20a, and a resin coating covering the cladding. As shown in FIG. 2, the tip portion 21 and the coating-removed portion 23 are portions where a predetermined length of the resin coating is removed from the tip surface 20c of each MCF 20, exposing the cladding 20b. The tip portion 21 extends in the Z direction from the tip surface 20c toward the introduction hole 35. The coating-removed portion 23 is continuous with the tip portion 21. At the introduction hole 35, the coating-removed portion 23 extends in the Z direction to a first end 22a of the coating portion 22 in the Z direction. The coating portion 22 extends from the first end 22a in the Z direction.

[0023] The ferrule 30 includes a ferrule body 31 configured to house multiple holding components 10 and multiple MCFs 20 therein. The ferrule body 31 has a front end 32a (ferrule front end) and a rear end 32b (ferrule rear end) opposite the front end 32a in the Z direction. The ferrule body 31 includes a front end face 33 provided at the front end 32a and an opening 34 provided at the rear end 32b. As shown in FIGS. 1 and 2, the ferrule 30 further includes an introduction hole 35, multiple fiber insertion holes 40, a pair of guide holes 36, and a window 37. The front end face 33 intersects with the Z direction and is inclined with respect to a plane perpendicular to the Z direction. In the example shown in FIG. 2, the front end face 33 is flush with the tip faces 20c of the MCFs 20.

[0024] The introduction hole 35 is provided in the ferrule body 31 from the rear end 32b toward the front end 32a. The introduction hole 35 extends, for example, from the opening 34 to the center position of the ferrule 30 in the Z direction. The introduction hole 35 is open at the opening 34. A cross section of the introduction hole 35 intersecting the Z direction is, for example, rectangular with the X direction as the longitudinal direction. The introduction hole 35 holds each holding part 10 together. The holding part 10 is placed and positioned in the introduction hole 35.

[0025] As shown in FIGS. 2 and 3 , each of the plurality of fiber insertion holes 40 extends along the Z direction from a portion 35a of the introduction hole 35 closer to the front end 32a to the front end 32a. The portion 35a of the introduction hole 35 closer to the front end 32a is closer to the front end 32a than the center position of the introduction hole 35 in the Z direction. Each of the plurality of fiber insertion holes 40 holds a plurality of MCFs 20. For example, each of the plurality of fiber insertion holes 40 is configured to be able to hold the tip portions 21 of the plurality of MCFs 20. The plurality of fiber insertion holes 40 are arranged one-dimensionally or two-dimensionally on the front end face 33. The plurality of fiber insertion holes 40 are aligned along at least one of the X direction and the Y direction on the front end face 33. For example, 16 fiber insertion hole rows aligned along the X direction are aligned in two rows along the Y direction. Each fiber insertion hole 40 holds the tip portion 21 of one of the MCFs 20.

[0026] The configuration of the fiber insertion hole 40 will now be described in detail with reference to FIG. 5. FIG. 5 is a schematic cross-sectional view showing the cross-sectional shape of the fiber insertion hole 40. As shown in FIG. 5, each of the multiple fiber insertion holes 40 has a fiber holding portion 41, an introduction portion 42, and a tapered portion 43 connecting the fiber holding portion 41 and the introduction portion 42. The fiber holding portion 41 extends along the Z direction from the front end 32a toward the introduction hole 35. The fiber holding portion 41 is open at the front end 32a. The rear end of the fiber holding portion 41 communicates with the tapered portion 43. The fiber holding portion 41 has a constant inner diameter. The inner diameter of the fiber holding portion 41 corresponds to the outer diameter of the tip portion 21 of the MCF 20. For example, the inner diameter of the fiber holding portion 41 is the same as or slightly larger than the outer diameter of the tip portion 21 of the MCF 20. The inner diameter of the fiber holding part 41 is, for example, 0.126 mm. The length of the fiber holding part 41 in the Z direction is, for example, 1.7 mm. The cross-sectional shape of the fiber holding part 41 intersecting the Z direction corresponds to the cross-sectional shape of the tip part 21 of the MCF 20, and is, for example, a circular shape. When the tip part 21 of the MCF 20 is inserted into the fiber insertion hole 40, the fiber holding part 41 holds the tip part 21.

[0027] The guiding portion 42 extends from the guiding hole 35 toward the front end 32a along the Z direction. The guiding portion 42 is open at the guiding hole 35. The front end of the guiding portion 42 communicates with the tapered portion 43. The guiding portion 42 has a constant inner diameter. The inner diameter of the guiding portion 42 is larger than the inner diameter of the fiber holding portion 41. The inner diameter of the guiding portion 42 is larger than the outer diameter of the MCF 20. The inner diameter of the guiding portion 42 is, for example, 2.0 mm. The length of the guiding portion 42 in the Z direction is, for example, 1.0 mm. The cross-sectional shape of the guiding portion 42 intersecting the Z direction corresponds to the cross-sectional shape of the tip portion 21 of the MCF 20 and is, for example, a circular shape. When the tip portion 21 of the MCF 20 is inserted into the fiber insertion hole 40, the tip portion 21 passes through the inside of the guiding portion 42 and reaches the tapered portion 43.

[0028] The tapered portion 43 has a tapered shape. 4 and , the front end 44 and the rear end 4 opposite in the Z direction 5 and The cross section of the fiber insertion hole 40 taken along the center line axis L2 and the inner surface 43a of the tapered portion 43 have two intersecting lines. The front end 44 and the rear end 45 are opposite ends in the Z direction of one of the two intersecting lines.

[0029] The tapered portion 43 extends from the front end 44 to the rear end 45 along the Z direction. The ratio of the length of the tapered portion 43 to the length of the fiber insertion hole 40 in the Z direction may be 1 / 5 or more and 3 / 4 or less, or 2 / 5 or more and 2 / 3 or less, for example, 2 / 5. The length of the tapered portion 43 in the Z direction is, for example, 1.3 mm. The tapered portion 43 communicates with the fiber holding portion 41 at the front end 44. At the front end 44, the inner surface 43a of the tapered portion 43 is continuous with the inner surface 41a of the fiber holding portion 41. The inner diameter of the tapered portion 43 at the front end 44 is the same as the inner diameter of the fiber holding portion 41. The tapered portion 43 communicates with the introduction portion 42 at the rear end 45. At the rear end 45, the inner surface 43a of the tapered portion 43 is continuous with the inner surface 42a of the introduction portion 42. The inner diameter of the tapered portion 43 at the rear end 45 matches the inner diameter of the lead-in portion 42 .

[0030] The inner diameter of the tapered portion 43 at the front end 44 is smaller than the inner diameter of the tapered portion 43 at the rear end 45. The inner diameter of the tapered portion 43 increases from the front end 44 toward the rear end 45. The change in the inner diameter of the tapered portion 43 is constant. In a cross section along the center line axis L2 of the fiber insertion hole 40, a straight line L1 connecting the front end 44 and the rear end 45 of the tapered portion 43 is (straight The line L1 coincides with the inner surface 43a of the tapered portion 43. That is, the intersection line between the inner surface 43a of the tapered portion 43 and the cross section along the centerline axis L2 is linear. The angle θ1 between the line L1 and the centerline axis L2 of the fiber insertion hole 40 may be 1 degree or more and 14 degrees or less, or 5 degrees or more and 10 degrees or less, or may be, for example, 8 degrees. When the tip portion 21 of the MCF 20 is inserted into the fiber insertion hole 40, the tip portion 21 comes into contact with the inner surface 43a of the tapered portion 43, and thereby moves gently in a direction approaching the centerline axis L2 of the fiber insertion hole 40 and the fiber holding portion 41. In this way, the tip portion 21 is guided and organized by the fiber holding portion 41 of the fiber insertion hole 40.

[0031] Next, a method for manufacturing the optical connector 1 using the above-described ferrule 30 will be described. Fig. 6 is a flowchart showing a method for manufacturing the optical connector 1. When manufacturing the optical connector 1, first, the ferrule 30 is prepared (step S1). Also, a plurality of MCFs 20 are prepared (step S2).

[0032] Next, a corresponding MCF 20 among the plurality of MCFs 20 is inserted into each of the plurality of fiber insertion holes 40 (step S3). Specifically, first, the coating-removed portions 23 of the plurality of MCFs 20 are placed in the plurality of V-grooves of the holding component 10, and each MCF 20 is rotated and aligned around the central axis. At this time, each MCF 20 is rotated and aligned one by one with respect to the holding component 10. Thereafter, the holding component 10 and each MCF 20 are fixed with an adhesive, and the plurality of holding components 10 are stacked in the Y direction. The adhesive is, for example, a UV-curable adhesive or a thermosetting adhesive. Then, with the holding components 10 fixed to each other, each holding component 10 is inserted into the introduction hole 35 of the ferrule 30. At this time, although the plurality of MCFs 20 are held by the holding component 10 and fixed with the adhesive, a certain degree of rotation (axial misalignment) may occur on the tip side of the holding component 10.

[0033] The tip portion 21 of the MCF 20, whose rotational alignment has been temporarily fixed in this manner, is inserted through the introduction hole 35 and then further inserted into the fiber insertion hole 40. At this time, in the ferrule 30 used in this embodiment, the tapered portion 43 of the fiber insertion hole 40 has a gentle tapered shape as described above, so that axial misalignment is unlikely to occur when the MCF 20 (tip portion 21) temporarily fixed to the holding component 10 comes into contact with the inner surface of the fiber insertion hole 40. Therefore, the tip portion 21 of the MCF 20 is housed and held in the fiber holding portion 41 of the fiber insertion hole 40 with axial misalignment of the MCF 20 suppressed.

[0034] Next, the multiple MCFs 20 are fixed to the ferrule 30 (step S4). Specifically, an adhesive is introduced through the window 37 of the ferrule 30, and the multiple holding components 10 and the multiple MCFs 20 are fixed to the ferrule 30 by the adhesive. For example, a thermosetting adhesive is introduced through the window 37 provided in the upper part of the ferrule 30 and thermally cured to fix the fiber insertion hole 40 and the tip portion 21. In this way, the optical connector shown in FIGS. 1 and 2 is produced.

[0035] The following describes the effects of manufacturing an optical connector 1 using the ferrule 30, in comparison with a case where a conventional ferrule is used. Fig. 7 is a schematic diagram showing a fiber insertion hole of a conventional ferrule. Figs. 8 and 9 are schematic diagrams for explaining a case where an MCF 20 is inserted into a conventional fiber insertion hole.

[0036] In the fiber insertion hole 1040 of a conventional ferrule, the angle θ2 between the center line axis L4 of the fiber insertion hole 1040 and the line L3 connecting the front end 44 and the rear end 45 of the tapered portion 1043 in a cross section taken along the center line axis L4 is equal to or greater than 15 degrees and equal to or less than 20 degrees. When an MCF 20 is inserted into the conventional fiber insertion hole 1040, the MCF 20 is inserted at various angles, rather than being necessarily parallel to or coaxial with the center line axis L4 of the fiber insertion hole 1040. Therefore, as shown in FIG. 8 , after being guided into the introducing portion 42, the MCF 20 is guided into the fiber holding portion 41 (aligned toward the fiber holding portion 41) while coming into strong contact with the inner surface of the tapered portion 1043 and receiving frictional force from the inner surface of the tapered portion 1043. 9, this frictional force causes the MCF 20 to rotate at the tapered portion 1043, and the position of the core 20a of the MCF 20 shifts in the circumferential direction of the MCF 20. If the MCF 20 is fixed in this shifted state to form the optical connector 1, the optical coupling efficiency between the MCF 20 of such optical connector 1 and an MCF held by another ferrule will decrease.

[0037] On the other hand, in the ferrule 30 according to the present embodiment, the angle between the centerline axis L2 of each of the plurality of fiber insertion holes 40 and the straight line L1 connecting the front end 44 and the rear end 45 of the tapered portion 43 in a cross section taken along the centerline axis L2 is between 1 degree and 14 degrees, and the shape of the tapered portion 43 is a gentle taper. This gentler taper configuration than conventional configurations reduces the frictional force exerted by the inner surface 43a of the tapered portion 43 when the MCF 20 is inserted into the fiber insertion hole 40 and comes into contact with the inner surface 43a of the tapered portion 43, compared to a ferrule having a conventional fiber insertion hole 1040. This reduces the likelihood of the MCF 20 rotating when inserted into the fiber insertion hole 40, causing circumferential misalignment (axial misalignment) of the plurality of cores 20a of the MCF 20 (i.e., rotation is less likely to occur). As a result, when an MCF 20 that requires rotational alignment is inserted into a ferrule 30, axial misalignment of the MCF 20 is suppressed, thereby suppressing a decrease in optical coupling efficiency between the MCF 20 and MCFs 20 in other ferrules 30.

[0038] Furthermore, in the ferrule 30 according to this embodiment, in a cross section taken along the centerline axis L2, the straight line L1 coincides with the inner surface 43a of the tapered portion 43. In this case, because the inner surface 43a of the tapered portion 43 is flat, the MCF 20 in contact with the inner surface 43a of the tapered portion 43 is further prevented from rotating and causing axial misalignment. As a result, when an MCF 20 that requires rotational alignment is inserted into the ferrule 30, axial misalignment of the MCF 20 is further suppressed, thereby further suppressing a decrease in optical coupling efficiency between the MCF 20 and MCFs 20 held in other ferrules 30.

[0039] Furthermore, in the ferrule 30 according to this embodiment, each of the multiple fiber insertion holes 40 further includes a guide portion 42. The guide portion 42 extends from the guide hole 35 along the Z direction and communicates with the tapered portion 43 at a rear end 45. The guide portion 42 has a constant inner diameter. In this case, the guide portion 42, which first receives the MCF 20 introduced from the guide hole 35, has a constant inner diameter. Therefore, the MCF 20 can be inserted into the fiber insertion hole 40 while preventing the MCF 20 from contacting the inner surface 42a of the guide portion 42. As a result, rotation of the MCF 20 and axial misalignment during insertion of the MCF 20 into the fiber insertion hole 40 are further prevented.

[0040] Furthermore, in the ferrule 30 according to this embodiment, the ratio of the length of the tapered portion 43 to the length of each of the plurality of fiber insertion holes 40 in the Z direction is 1 / 5 or more and 3 / 4 or less. In this case, since the length ratio is 3 / 4 or less, the fiber holding portion 41 of the fiber insertion hole 40 can be made sufficiently long in the Z direction. This allows each fiber holding portion 41 to stably support each MCF 20. Furthermore, since the length ratio is 1 / 5 or more, the tapered portion 43 can be made sufficiently long in the Z direction. This allows the inner diameter of the tapered portion 43 at the rear end 45 to be sufficiently large, which further prevents the MCF 20 from coming into contact with the inner surface 43a of the tapered portion 43 near the rear end 32b and rotating, causing axial misalignment, when the MCF 20 is inserted into the fiber insertion hole 40.

[0041] Furthermore, in the ferrule 30 according to this embodiment, the angle between the center line axis L2 of each of the plurality of fiber insertion holes 40 and the straight line L1 in the cross section taken along the center line axis L2 may be 5 degrees or more and 10 degrees or less. In this case, rotation of the MCF 20 and axial misalignment caused by the rotation of the MCF 20 when the MCF 20 is inserted into the fiber insertion hole 40 is further suppressed. As a result, when an MCF 20 requiring rotational alignment is inserted into the ferrule 30, axial misalignment of the MCF 20 is further suppressed, thereby further suppressing a decrease in optical coupling efficiency between the MCF 20 and MCFs 20 held in other ferrules 30.

[0042] In the ferrule 30 according to this embodiment, the inner diameter of the introduction portion 42 is larger than the inner diameter of the fiber holding portion 41. In this case, it is possible for each fiber holding portion 41 to stably hold the tip portion 21 of each MCF 20, and it is possible to improve the ease of inserting the MCF 20 into the introduction portion 42.

[0043] An optical connector 1 according to one embodiment includes a ferrule 30 and a plurality of MCFs 20, each having a plurality of cores 20a. The plurality of MCFs 20 are held in a plurality of fiber insertion holes 40, respectively. In this optical connector 1, the plurality of MCFs 20 are fixed to the above-described ferrule 30. This configuration prevents the MCFs 20 from rotating and causing axial misalignment when the MCFs 20 are inserted into the fiber insertion holes 40. This prevents axial misalignment of the MCFs 20 when inserting an MCF 20 that requires rotational alignment into the ferrule 30, thereby preventing a decrease in optical coupling efficiency between the MCF 20 and MCFs 20 held in other ferrules 30.

[0044] A manufacturing method of an optical connector 1 according to one embodiment includes the steps of preparing a ferrule 30, preparing a plurality of MCFs 20, each having a plurality of cores 20a, and inserting a corresponding one of the plurality of MCFs 20 into a plurality of fiber insertion holes 40. In this manufacturing method of the optical connector 1, a ferrule 30 having fiber insertion holes 40 with a gently tapered shape is used, and the MCFs 20 are inserted into such fiber insertion holes 40. This further suppresses the MCFs 20 from rotating and causing axial misalignment. This further suppresses axial misalignment of the MCFs 20 when inserting an MCF 20 that requires rotational alignment into the ferrule 30, thereby realizing an optical connector 1 that can further suppress a decrease in optical coupling efficiency between the MCF 20 and MCFs 20 held in other ferrules 30.

[0045] The ferrule 30, the optical connector 1, and the method for manufacturing the optical connector 1 according to the present disclosure have been described in detail above. However, the present invention is not limited to the above-described embodiment and can be applied to various other embodiments and modifications. In the above-described embodiment, multiple MCFs 20 are inserted into multiple fiber insertion holes 40, but the present invention is not limited to this. For example, multiple optical fibers 20 may be inserted into the multiple fiber insertion holes 40, respectively, as long as the optical fibers 20 are optical fibers that require rotational alignment. For example, the optical fibers 20 may be either polarization-maintaining fibers or bundle fibers, or may be optical fibers other than those described above. In this case, since the optical fibers 20 are optical fibers that require rotational alignment, axial misalignment of the optical fibers 20 is suppressed when the optical fibers 20 are inserted into the ferrules 30, thereby suppressing a decrease in optical coupling efficiency between the optical fibers 20 and the optical fibers 20 held in other ferrules 30.

[0046] In the above embodiment, the ferrule 30 has a plurality of fiber insertion holes 40, but this is not limiting. Figures 10 to 12 are schematic diagrams showing various shapes of the fiber insertion holes of ferrules 30 according to modified examples.

[0047] [First Modification] As shown in FIG. 10 , unlike the fiber insertion hole 40, the fiber insertion hole 140 according to the first modification does not have an introduction portion 42. That is, the fiber insertion hole 140 is configured to have only a fiber holding portion 41 and a tapered portion 143. The fiber holding portion 41 extends from the front end 32 a toward the introduction hole 35 along the Z direction. The tapered portion 143 communicates with the fiber holding portion 41 at the front end 44. The tapered portion 143 extends from the front end 44 to the rear end 45 along the Z direction. The tapered portion 143 communicates with the introduction hole 35 at the rear end 45. The inner diameter of the tapered portion 143 at the front end 44 is smaller than the inner diameter of the tapered portion 143 at the rear end 45. The inner diameter of the tapered portion 143 increases from the front end 44 toward the rear end 45. The change in the inner diameter of the tapered portion 143 is constant. A straight line L5 connecting the front end 44 and the rear end 45 of the tapered portion 143 in a cross section along the center line axis L6 of the fiber insertion hole 140 (straight The angle θ3 between the line L5 and the center line axis L6 of the fiber insertion hole 140 is the same as the angle θ1 in the above embodiment. In a cross section taken along the center line axis L6 of the fiber insertion hole 140, the line L5 coincides with the inner surface 143a of the tapered portion 143. For example, the intersection line between the inner surface 143a of the tapered portion 143 and the cross section taken along the center line axis L6 is linear.

[0048] [Second Modification] 11 , a fiber insertion hole 240 according to the second modification includes a fiber holding portion 41, an introduction portion 42, and a tapered portion 243 connecting the fiber holding portion 41 and the introduction portion 42. In this fiber insertion hole 240, the inner diameter of the tapered portion 243 at the front end 44 is smaller than the inner diameter of the tapered portion 243 at the rear end 45. The inner diameter of the tapered portion 243 increases from the front end 44 toward the rear end 45. Unlike the fiber insertion hole 40, in the fiber insertion hole 240, the change in the inner diameter of the tapered portion 243 is not constant. For example, the slope of the inner surface 243 a of the tapered portion 243 becomes gentler as it approaches the front end 44 (the gradient of the inner surface 243 a changes continuously toward the front end 44). Specifically, in a cross section along the center line axis L8 of the fiber insertion hole 240, a virtual line L7 connecting the front end 44 and the rear end 45 of the tapered portion 243 is (straight The imaginary line) does not have to coincide with the inner surface 243a of the tapered portion 243. The angle between the tangent at the tangent point on the inner surface 243a of the tapered portion 243 and the center line axis L8 of the fiber insertion hole 240 decreases as the tangent point approaches the front end 44 in the Z direction. At the front end 44, the inner surface 243a of the tapered portion 243 is continuous with the inner surface 41a of the fiber holding portion 41. For example, at the front end 44, the inner surface 243a of the tapered portion 243 is flush with the inner surface 41a of the fiber holding portion 41. The angle θ4 between the imaginary line L7 in the cross section taken along the center line axis L8 of the fiber insertion hole 240 and the center line axis L8 of the fiber insertion hole 240 is the same as the angle θ1 in the above embodiment.

[0049] In the fiber insertion hole 240 according to the second modification, in a cross section along the center line axis L8, the angle between the tangent at the contact point on the inner surface 243a of the tapered portion 243 and the center line axis L8 of the fiber insertion hole 240 decreases as the contact point approaches the front end 44 in the Z direction. 、 The inclination of the inner surface 243a of the tapered portion 243 becomes gentler as it approaches the front end 44 of the tapered portion 243. This can further reduce the friction force that the MCF 20 receives from the inner surface 243a of the tapered portion 243 near the front end 44 of the tapered portion 243. In addition, the inner diameter of the tapered portion 243 at the rear end 45 can be increased without changing the length of the tapered portion 243 in the Z direction. This can prevent the MCF 20 from coming into contact with the inner surface 243a of the tapered portion 243 near the rear end 45 when inserting the MCF 20 into the fiber insertion hole 40. As a result, rotation of the MCF 20 and axial misalignment when inserting the MCF 20 into the fiber insertion hole 40 can be further prevented. As a result, when an MCF 20 that requires rotational alignment is inserted into a ferrule 30, the axial misalignment of the MCF 20 is further suppressed, thereby further suppressing the decrease in optical coupling efficiency between the MCF 20 and MCFs 20 held in other ferrules 30.

[0050] [Third Modification] 12, the fiber insertion hole 340 according to the third modification does not have the introduction portion 42, unlike the fiber insertion hole 240 according to the second modification. This fiber insertion hole 340 is configured to have only the fiber holding portion 41 and the tapered portion 343. .centre The fiber holding portion 41 extends from the front end 32a toward the introduction hole 35 along the Z direction. The tapered portion 343 communicates with the fiber holding portion 41 at the front end 44. The tapered portion 343 extends from the front end 44 to the rear end 45 along the Z direction. The tapered portion 343 communicates with the introduction hole 35 at the rear end 45. The inner diameter of the tapered portion 343 at the front end 44 is smaller than the inner diameter of the tapered portion 343 at the rear end 45. The inner diameter of the tapered portion 343 increases from the front end 44 toward the rear end 45. The change in the inner diameter of the tapered portion 343 is not constant. For example, the inner surface 343a of the tapered portion 343 may become more gradual as it approaches the front end 44 (the gradient of the inner surface 343a may change continuously toward the front end 44). A virtual line L9 connecting the center line axis L10 of the fiber insertion hole 340 and the front end 44 and the rear end 45 of the tapered portion 343 in a cross section along the center line axis L10 (straight The angle θ5 between the tangent line and the center line axis L10 of the fiber insertion hole 340 is the same as the angle θ1 in the above embodiment. The angle between the tangent line at the tangent point on the inner surface 343a of the tapered portion 343 and the center line axis L10 of the fiber insertion hole 340 may decrease as the tangent point approaches the front end 44 in the Z direction. The inner surface 343a of the tapered portion 343 is continuous with the inner surface 41a of the fiber holding portion 41 at the front end 44. For example, the inner surface 343a of the tapered portion 343 is flush with the inner surface 41a of the fiber holding portion 41 at the front end 44. The fiber insertion hole 340 according to the third modification achieves the same effects as those achieved by the fiber insertion hole 240 according to the second modification. [Explanation of symbols]

[0051] 1...Optical connector 10...Retaining part 20...MCF (optical fiber) 20a...Core 20b...Clad 20c…Tip surface 21...Tip 22...Covering part 22a...first end 23...Sheathing removal section 30...Ferrule 31...Ferrule body 32a…Front end (ferrule front end) 32b…Rear end (ferrule rear end) 33…Front end surface 34…Aperture 35...Inlet hole 35a: Portion of the introduction hole near the front end of the ferrule 36...Guide hole 37...Window 40...Fiber insertion hole 41...Fiber holding part 41a...Inside 42...Introduction 42a...Inner surface 43...Tapered section 43a...Inner surface 44…before end 4 5...after end 1 40...Fiber insertion hole 143...Tapered section 143a...Inner 240...Fiber insertion hole 243...Tapered section 243a…Inner 340...Fiber insertion hole 343...Tapered section 343a…Inner 1040...Fiber insertion hole 1043...Tapered section L1,L5…straight line (straight line) L3…straight line L7, L9...imaginary lines (straight line) L2,L4,L6,L8,L10…Center line axis θ1,θ2,θ3,θ4,θ5...Angles

Claims

1. a ferrule body having a ferrule front end and a ferrule rear end opposite the ferrule front end in a first direction; an introduction hole provided in the ferrule body from the rear end of the ferrule toward the front end of the ferrule; a plurality of fiber insertion holes configured to be able to hold tip ends of a plurality of optical fibers, respectively, and extending along the first direction from a portion of the introduction hole near the front end of the ferrule to the front end of the ferrule; each of the plurality of fiber insertion holes has a tapered portion including a tapered shape, and a fiber holding portion that communicates with the tapered portion near a front end of the ferrule and extends to the front end of the ferrule along the first direction; the tapered portion includes a front end and a rear end opposite the front end in the first direction, and extends from the rear end to the front end such that an inner diameter of the tapered portion at the front end is smaller than an inner diameter of the tapered portion at the rear end; an angle between a center line axis of each of the plurality of fiber insertion holes and a straight line connecting the front end and the rear end of the tapered portion in a cross section taken along the center line axis is equal to or greater than 1 degree and equal to or less than 14 degrees.

2. 2. The ferrule according to claim 1, wherein, in a cross section taken along the centerline axis, the straight line coincides with an inner surface of the tapered portion.

3. 2. The ferrule of claim 1, wherein, in a cross section taken along the centerline axis, an angle between a tangent to a tangent point on an inner surface of the tapered portion and the centerline axis decreases as the tangent point approaches the forward end of the tapered portion in the first direction.

4. each of the plurality of fiber insertion holes further includes an introduction portion extending from the introduction hole along the first direction and communicating with the tapered portion at the rear end of the tapered portion; The ferrule according to claim 1 , wherein the introduction portion has a constant inner diameter.

5. 4. The ferrule according to claim 1, wherein a ratio of a length of the tapered portion to a length of each of the plurality of fiber insertion holes in the first direction is equal to or greater than 1 / 5 and equal to or less than 3 / 4.

6. 4. The ferrule according to claim 1, wherein the angle between the center axis of each of the plurality of fiber insertion holes and the straight line in a cross section taken along the center axis is equal to or greater than 5 degrees and equal to or less than 10 degrees.

7. The ferrule according to any one of claims 1 to 3; a plurality of optical fibers held in the plurality of fiber insertion holes, An optical connector, wherein each of the plurality of optical fibers is one of a multi-core optical fiber, a polarization-maintaining fiber, and a bundle fiber.

8. A step of preparing a ferrule according to any one of claims 1 to 3; providing a plurality of optical fibers; inserting a corresponding optical fiber among the plurality of optical fibers into each of the plurality of fiber insertion holes; Equipped with A method for manufacturing an optical connector, wherein in the step of preparing the plurality of optical fibers, each of the plurality of optical fibers is one of a multi-core optical fiber, a polarization-maintaining fiber, and a bundle fiber.