Optical fiber holding component, optical fiber coupling structure, optical connector, optical coupling structure, and method for manufacturing optical fiber coupling structure

Abstract

An optical fiber holding component according to the present disclosure comprises: a first surface and a second surface that are arranged in a first direction; and a plurality of through-holes that penetrate in a first direction between the first surface and the second surface. Each optical fiber of a plurality of optical fibers includes: an insertion part that is inserted and held in each through-hole of the plurality of through-holes; and a projection part that projects outward from the through-hole and is inserted into each ferrule hole of a plurality of ferrule holes. The minimum value of the inner diameter of the through-hole is equal to or greater than the maximum value of the outer diameter of the insertion part. When the center axis of insertion part is maximally inclined with respect to the center axis of the through-hole within the through-hole in a state where the center axis of the ferrule hole coincides with the center axis of the through-hole when viewed along the first direction, a tip of the projection part is located inside the inner surface of the ferrule hole when viewed along the first direction.

Description

Optical fiber holding component, optical fiber coupling structure, optical connector, optical coupling structure, and method for manufacturing optical fiber coupling structure

[0001] The present disclosure relates to an optical fiber holding component, an optical fiber coupling structure, an optical connector, an optical coupling structure, and a manufacturing method of an optical fiber coupling structure. This application claims priority to Japanese Application No. 2023-103573 filed on June 23, 2023, and incorporates all of the contents of said Japanese application by reference.

[0002] Conventionally, a hole array described in Patent Document 1 is known as an optical fiber holding component for holding a plurality of optical fibers. This hole array has holding holes that hold a plurality of optical fibers, respectively. The plurality of optical fibers are inserted into the interior of a ferrule while being held in the plurality of holding holes, respectively. The tip portions of the plurality of optical fibers extend from the hole array and are inserted into a plurality of ferrule holes formed in the ferrule, respectively.

[0003] International Publication No. 2018 / 135368

[0004] A holding equipment for optical fiber according to an embodiment of the present disclosure is arranged inside a ferrule having a plurality of ferrule holes formed therein, and holds a plurality of optical fibers inserted into the plurality of ferrule holes, respectively. The holding equipment for optical fiber comprises a first surface and a second surface aligned in a first direction, and a plurality of through holes penetrating in the first direction between the first surface and the second surface, and aligned in a second direction intersecting the first direction, corresponding to the plurality of ferrule holes. Each of the plurality of optical fibers includes an insertion part inserted into and held in each of the plurality of through holes, and a protrusion protruding to the outside from the through hole and inserted into each of the plurality of ferrule holes. The minimum value of the inner diameter of the through hole is equal to or greater than the maximum value of the outer diameter of the insertion part. In a state where the central axis of the ferrule hole coincides with the central axis of the through hole when viewed along the first direction, when the central axis of the insertion part is maximally inclined with respect to the central axis of the through hole inside the through hole, the tip of the protrusion is located inside the inner surface of the ferrule hole when viewed along the first direction.

[0005] 1 is a perspective view of holding equipment for optical fiber according to one embodiment. Fig. 2 is a cross-sectional view of holding equipment for optical fiber of Fig. 1. Fig. 3 is a cross-sectional view of an optical fiber coupling structure equipped with holding equipment for optical fiber of Fig. 1. Fig. 4 is a front view of the optical fiber coupling structure of Fig. 3(a). Fig. 5 is a cross-sectional view for explaining an example of a manufacturing method of the optical fiber coupling structure. Fig. 6 is an exploded perspective view of an optical connector equipped with the optical fiber coupling structure of Fig. 3. Fig. 7 is a perspective view of the optical connector of Fig. 6. Fig. 8 is a cross-sectional view of the optical connector of Fig. 7. Fig. 9 is a perspective view showing an optical coupling structure equipped with a first optical connector and a second optical connector as optical connectors. Fig. 10 is a view for explaining a method for setting an inner diameter of a through hole of holding equipment for optical fiber. Fig. 11 is a front view of holding equipment for optical fiber of Fig. 10. Fig. 12 is a view for explaining a problem of holding equipment for optical fiber according to a comparative example. Fig. 13 is a cross-sectional view of an optical connector according to modified example 1. Fig. 14 is a view for explaining a method for setting an inner diameter of a through hole of holding equipment for optical fiber equipped in the optical connector of Fig. 13. Fig. 15 is a front view of holding equipment for optical fiber of Fig. 14. Fig. 16a is a cross-sectional view of an optical connector according to modified example 2. Fig. 16b is a plan view of holding equipment for optical fiber that the optical connector of Fig. 16a has. Fig. 17 is a perspective view showing another example of holding equipment for optical fiber of Fig. 16b. Fig. 18a is a cross-sectional view of an optical connector according to modified example 3. Fig. 18b is a plan view of holding equipment for optical fiber that the optical connector of Fig. 18a has.

[0006] [Problem to be Solved by the Present Disclosure] When mounting the hole array described above on a ferrule, the optical fibers may be fixed in a tilted state in the holding holes of the hole array. In this case, even if the hole array is inserted straight into the ferrule, the tips of the optical fibers protruding from the hole array may strike the wall surfaces surrounding the ferrule holes, making it impossible to insert the tips of the optical fibers into the ferrule holes. To address this issue, for example, it is conceivable to vertically shift the hole array relative to the ferrule and forcibly insert the tips of the optical fibers into the ferrule holes while pressing them against the inner surface of the ferrule holes. However, with this method, the tips of the optical fibers may come into strong contact with the inner surface of the ferrule holes, which may apply a large load to the optical fibers. Such loads may cause problems such as damage to the optical fibers or degradation of optical transmission characteristics, thereby reducing the reliability of the optical fibers.

[0007] The present disclosure provides an optical fiber holding equipment, an optical fiber coupling structure, an optical connector, an optical coupling structure, and a method for manufacturing an optical fiber coupling structure that can improve the reliability of optical fibers.

[0008] [Effects of the Present Disclosure] According to the holding equipment for optical fiber, the optical fiber coupling structure, the optical connector, the optical coupling structure, and the manufacturing method of the optical fiber coupling structure of the present disclosure, the reliability of the optical fiber can be improved.

[0009] [Description of Embodiments of the Present Disclosure] First, the contents of the embodiments of the present disclosure will be listed and described.

[0010] (1) A holding equipment for optical fiber according to an embodiment of the present disclosure is arranged inside a ferrule having a plurality of ferrule holes formed therein, and holds a plurality of optical fibers inserted into the plurality of ferrule holes, respectively. The holding equipment for optical fiber comprises a first surface and a second surface aligned in a first direction, and a plurality of through holes that penetrate between the first surface and the second surface in the first direction and are aligned in a second direction intersecting the first direction, corresponding to the plurality of ferrule holes. Each of the plurality of optical fibers includes an insertion part that is inserted into and held in each of the plurality of through holes, and a protrusion that protrudes outward from the through hole and is inserted into each of the plurality of ferrule holes. The minimum value of the inner diameter of the through hole is equal to or greater than the maximum value of the outer diameter of the insertion part. In a state where the central axis of the ferrule hole coincides with the central axis of the through hole when viewed along the first direction, when the central axis of the insertion part is maximally inclined with respect to the central axis of the through hole inside the through hole, the tip of the protrusion is located inside the inner surface of the ferrule hole when viewed along the first direction.

[0011] In the above-mentioned holding equipment for optical fiber, the insertion parts of multiple optical fibers are inserted and held in multiple through holes that penetrate between the first surface and the second surface in the first direction. In this state, the protruding part of each optical fiber protrudes outward from the through hole and is inserted into each ferrule hole. In the above-mentioned configuration, when the central axis of the through hole coincides with the central axis of the ferrule hole when viewed along the first direction, and the central axis of the optical fiber insertion part is tilted to the maximum extent with respect to the central axis of the through hole inside the through hole, the tip of the protruding part is located inside the inner surface of the ferrule hole when viewed along the first direction. In this case, no matter what angle the insertion part of the optical fiber is tilted at inside the through hole, when inserting holding equipment for optical fiber into the ferrule, the protruding part can be reliably inserted into the ferrule hole without the tip of the protruding part hitting hard against the inner surface of the ferrule hole or the wall surface surrounding the ferrule hole. This reduces the application of a large load to the optical fiber. As a result, the occurrence of problems such as damage to the optical fiber or deterioration of optical transmission characteristics can be reduced. Therefore, the above-mentioned holding equipment for optical fiber makes it possible to improve the reliability of the optical fiber.

[0012] (2) In the holding equipment for optical fiber described in (1) above, the maximum value of the inner diameter of the through hole may be smaller than the maximum value of the inner diameter of the ferrule hole. By reducing the maximum value of the inner diameter of the through hole in this way, the inclination of the insertion part inside the through hole can be reduced. Accordingly, the deviation of the tip of the protruding part from the through hole can be reduced. As a result, when inserting holding equipment for optical fiber into the inside of the ferrule, the protruding part can be inserted more reliably into the ferrule hole without the tip hitting hard against the inner surface of the ferrule hole.

[0013] (3) In the holding equipment for optical fiber described in (1) or (2) above, the optical fiber may include a coating removal portion where part of the coating is removed from the tip, and a coating portion where the coating remains. Of the coating removal portion and the coating portion, only the coating removal portion may be inserted into the through hole as the insertion portion. In this case, the maximum value of the inner diameter of the through hole can be reduced to match the outer diameter of the coating removal portion, so the inclination of the insertion portion inside the through hole can be reduced. Accordingly, the deviation of the tip of the protruding portion from the through hole can be reduced. As a result, when inserting holding equipment for optical fiber into the inside of the ferrule, the protruding portion can be inserted more reliably into the ferrule hole without the tip hitting hard against the inner surface of the ferrule hole.

[0014] (4) The holding equipment for optical fiber described in (3) above may further comprise a support part that is arranged between the through hole and the second surface in the first direction and can support the coating part that is arranged outside the through hole. In this case, the coating part of the optical fiber is supported by the support part of holding equipment for optical fiber, so that the inclination of the insertion part inside the through hole can be reduced. Accordingly, the deviation of the tip of the protruding part from the through hole can be reduced. As a result, when inserting holding equipment for optical fiber into the inside of the ferrule, the protruding part can be inserted into the ferrule hole more reliably without the tip hitting hard against the inner surface of the ferrule hole.

[0015] (5) In the holding equipment for optical fiber described in (1) or (2) above, the optical fiber may include a coating removal portion where part of the coating is removed from the tip, and a coating portion where the coating remains. Of the coating removal portion and the coating portion, only the coating portion may be inserted into the through hole as an insertion portion. In this case, the maximum inner diameter of the through hole is set large to match the outer diameter of the coating portion. Accordingly, the allowable range of deviation of the tip from the through hole to prevent the tip of the protrusion from contacting the inner surface of the ferrule hole becomes small. As a result, when inserting the protrusion into the ferrule hole, the tip is likely to hit the inner surface of the ferrule hole, etc. In contrast, with the above holding equipment for optical fiber, no matter what angle the insertion portion is tilted inside the through hole, as a result, when inserting holding equipment for optical fiber into the ferrule, the protrusion can be inserted into the ferrule hole more reliably without the tip hitting the inner surface of the ferrule hole, etc.

[0016] (6) In the holding equipment for optical fiber described in any one of (1) to (5) above, the through hole may include a constant diameter part having a constant inner diameter in a first direction capable of holding the insertion part, and an expanding diameter part formed between the constant diameter part in the first direction and the second surface, and the inner diameter expanding from the constant diameter part toward the second surface in the first direction. In this case, when inserting the optical fiber into the through hole, the tip of the optical fiber is guided by the expanding diameter part to the constant diameter part, so that the tip of the optical fiber can be reduced from coming into strong contact with the inner surface of the through hole, etc. This can more reliably reduce the application of a large load to the optical fiber.

[0017] (7) In the holding equipment for optical fiber described in any one of (1) to (6) above, the through hole may be configured to hold the insertion part rotatably around the central axis of the insertion part. In this case, the rotation position of the insertion part of the optical fiber can be adjusted. During this adjustment, the insertion part of the optical fiber is likely to tilt. Therefore, with the above configuration, the above-mentioned effect can be effectively achieved.

[0018] (8) In the holding equipment for optical fiber described in any one of (1) to (7) above, the optical fiber may include at least one core in an area shifted from the central axis of the optical fiber. In this case, the rotation position of the insertion part of the optical fiber can be adjusted. During this adjustment, the insertion part of the optical fiber is likely to tilt. Therefore, with the above configuration, the above-mentioned effects can be effectively achieved.

[0019] (9) The holding equipment for optical fiber according to any one of (1) to (8) above may further comprise a third surface connecting the first surface and the second surface in the first direction, and a plurality of injection holes extending from the third surface to intersect with the plurality of through holes and individually communicating with each of the plurality of through holes, through which adhesive for adhering a plurality of optical fibers to the plurality of through holes can be injected. In this case, when fixing the optical fibers in the through holes with adhesive, the adhesive can be individually injected into the through holes from a route separate from the through holes. By adjusting the position of the injection hole relative to the through holes and the injection amount of adhesive, etc., taking into account the fluidity of the adhesive, it is possible to reliably fill the gaps between the optical fibers and the through holes with adhesive. This allows the adhesive to be distributed evenly around the optical fiber, so that the stress generated when the adhesive hardens can be applied uniformly to the optical fiber. As a result, it is possible to reduce tilting of the optical fiber due to stress being applied in one direction. This makes it possible to more reliably insert the protruding portion into the ferrule hole when inserting the holding equipment for optical fiber into the ferrule without the tip strongly hitting the inner surface of the ferrule hole, etc.

[0020] (10) An optical fiber coupling structure according to an embodiment of the present disclosure comprises: holding equipment for optical fiber according to any one of the above (1) to (9); and a plurality of optical fibers inserted into a plurality of through holes, respectively, and fixed to the plurality of through holes by a cured product of an adhesive. Since this optical fiber coupling structure comprises any one of the above-mentioned holding equipment for optical fiber, it can improve the reliability of the optical fiber as described above.

[0021] (11) An optical connector according to an embodiment of the present disclosure includes the optical fiber coupling structure of (10) above and a ferrule into which the optical fiber coupling structure is inserted. The protruding portions of the optical fibers are inserted into the ferrule holes, respectively. Because this optical connector includes the optical fiber coupling structure described above, the reliability of the optical fibers can be improved, as described above.

[0022] (12) An optical coupling structure according to an embodiment of the present disclosure includes a first optical connector and a second optical connector as the optical connectors described in (11). The first optical connector and the second optical connector face each other across a gap in a first direction. Because this optical coupling structure includes the optical connectors described above, the reliability of the optical fiber can be improved, as described above. Furthermore, when the first optical connector and the second optical connector are not connected via physical contact (PC), the pressing force required for connecting the first optical connector and the second optical connector via PC is not required, making it possible to easily connect a larger number of optical fibers at once.

[0023] (13) A manufacturing method of an optical fiber coupling structure according to an embodiment of the present disclosure is a manufacturing method of the optical fiber coupling structure described in (10) above. This manufacturing method includes the steps of preparing auxiliary optical fiber holding components and fixing optical fiber holding components as holding components for optical fiber, arranging the auxiliary optical fiber holding components in a first direction relative to the holding components for fixing optical fiber, inserting an optical fiber in the first direction from the through hole of the holding component for fixing optical fiber to the through hole of the auxiliary holding component while the auxiliary holding components for fixing optical fiber and the holding components for fixing optical fiber are arranged in the first direction, injecting an adhesive into the through hole of the holding component for fixing optical fiber and hardening the adhesive while the inserting portion of the optical fiber is inserted into the through hole of the holding component for fixing optical fiber and the protruding portion of the optical fiber is inserted into the through hole of the holding component for auxiliary optical fiber, and removing the auxiliary holding component while the inserting portion is fixed to the holding component for fixing optical fiber. In this case, the auxiliary holding equipment for optical fiber is used as a jig to regulate the position of the tip of the protruding part of the optical fiber protruding from the through hole of the holding equipment for fixing. In this way, the position of the tip of the protruding part is regulated by the inner surface of the through hole of the auxiliary holding equipment for optical fiber, so that the position of the tip of the protruding part can be reduced from being significantly shifted outward from the through hole. Furthermore, by arranging a plurality of holding equipment for optical fiber in the first direction in this way, the overall length of these holding equipment for optical fiber in the first direction becomes longer. The longer this overall length, the smaller the tilt that can occur in the insertion part of the optical fiber inserted into the through hole of these holding equipment for optical fiber. As a result, when inserting the optical fiber held by the holding equipment for fixing optical fiber into the inside of the ferrule, it becomes possible to more reliably insert the protruding part into the ferrule hole without the tip hitting hard against the inner surface of the ferrule hole, etc.

[0024] (14) In the manufacturing method of the optical fiber coupling structure described in the above (13), in the step of arranging the auxiliary holding components for optical fiber in the first direction relative to the holding components for fixed optical fiber, the auxiliary holding components for optical fiber may be brought into contact with the holding components for fixed optical fiber in the first direction so that the through-holes of the auxiliary holding components for optical fiber communicate with the through-holes of the holding components for fixed optical fiber in the first direction. In this case, when inserting the optical fiber from the through-hole of the holding components for fixed optical fiber to the through-hole of the auxiliary holding components for optical fiber, the protruding portion of the optical fiber can be easily and reliably inserted into the through-hole of the auxiliary holding components for optical fiber, compared to the case where the auxiliary holding components for optical fiber are arranged with a gap from the holding components for fixed optical fiber.

[0025] [Details of the embodiments of the present disclosure] Specific examples of holding equipment for optical fiber, optical fiber coupling structure, optical connector, and optical coupling structure according to the embodiments of the present disclosure will be described below with reference to the drawings. The present disclosure 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. In the following description, the same elements in the description of the drawings will be given the same reference numerals, and duplicated descriptions will be omitted as appropriate.

[0026] [Embodiment] Fig. 1 is a perspective view of holding equipment for optical fiber 10 according to this embodiment. (a) of Fig. 2 is a cross-sectional view of holding equipment for optical fiber 10. (b) of Fig. 2 is another cross-sectional view of holding equipment for optical fiber 10. Each figure shows an XYZ orthogonal coordinate system. Holding equipment for optical fiber 10 has a rectangular parallelepiped appearance with, for example, the Y direction (an example of the "second direction" in this disclosure) as the longitudinal direction, the X direction (an example of the "first direction" in this disclosure) as the lateral direction, and the Z direction as the thickness direction. In the following description, "up and down" may be defined by the relative position of the Z coordinate, "front and back" by the relative position of the X coordinate, and "left and right" by the relative position of the Y coordinate. A larger Z coordinate is "up". A larger X coordinate is "front". A larger Y coordinate is "right".

[0027] The holding equipment 10 for optical fiber is placed inside the ferrule 30 while holding a plurality of optical fibers 20 (see FIG. 7 described later). The holding equipment 10 for optical fiber is made of, for example, a material such as quartz glass or a resin that can transmit ultraviolet light used when curing an ultraviolet curing adhesive. In this case, the holding equipment 10 for optical fiber can be manufactured cheaply and with high precision. The holding equipment 10 may be made of, for example, metal. In this case, high dimensional precision can be maintained, so the holding equipment 10 can be manufactured with higher precision. When the holding equipment 10 is made of quartz glass or metal, the frictional resistance between the holding equipment 10 and a plurality of optical fibers 20 can be reduced.

[0028] 1, holding equipment 10 for optical fiber comprises, for example, a front surface 10a (an example of "first surface" in this disclosure), a rear surface 10b (an example of "second surface" in this disclosure), an upper surface 10c, a lower surface 10d, a side surface 10e, and a side surface 10f. The front surface 10a is an end surface located at the front end of holding equipment 10 for optical fiber in the X direction. The rear surface 10b is an end surface located at the rear end of holding equipment 10 for optical fiber in the X direction. The front surface 10a and the rear surface 10b are, for example, flat surfaces along the YZ plane, and are arranged side by side along the X direction. The normal direction of the front surface 10a coincides, for example, with the normal direction of the rear surface 10b.

[0029] The upper surface 10c is an end surface located at the upper end of holding equipment for optical fiber 10 in the Z direction. The lower surface 10d is an end surface located at the lower end of holding equipment for optical fiber 10 in the Z direction. The upper surface 10c and the lower surface 10d are, for example, planes along the XY plane, and are arranged on both sides of a plurality of through holes 11 described later in the Z direction. The upper surface 10c and the lower surface 10d connect the front surface 10a and the rear surface 10b in the X direction. The normal direction of the upper surface 10c coincides with the normal direction of the lower surface 10d, for example. The upper surface 10c and the lower surface 10d may be perpendicular to the front surface 10a and the rear surface 10b, for example.

[0030] The side surface 10e is an end face located at a first end of holding equipment for optical fiber 10 in the Y direction. The side surface 10f is, for example, an end face located at a second end of holding equipment for optical fiber 10 in the Y direction. The side surfaces 10e and 10f are, for example, planes along the XZ plane, and are arranged on both sides of the plurality of through holes 11 in the Y direction. The side surfaces 10e and 10f connect the front surface 10a and the rear surface 10b in the X direction. The normal direction of the side surface 10e coincides with the normal direction of the side surface 10f, for example. The side surfaces 10e and 10f may be, for example, perpendicular to the front surface 10a, the rear surface 10b, the upper surface 10c, and the lower surface 10d.

[0031] The holding equipment for optical fiber 10 further comprises a plurality of through holes 11 penetrating in the X direction from the front surface 10a to the rear surface 10b. Each through hole 11 extends along the X direction, for example, and is arranged in a line along the Y direction. For example, each through hole 11 is formed at a position closer to the upper surface 10c than to the lower surface 10d in the Z direction. In this embodiment, the case where 12 through holes 11 are arranged in a line (12 x 1 line) at equal intervals in the Y direction is exemplified. However, the number of through holes 11 is not limited to 12, and may be other numbers such as 4, 8, or 16. Each through hole 11 does not have to be arranged in a line, and may be arranged in two or more lines.

[0032] 2(a) shows a cut surface of holding equipment 10 for optical fiber in the XY plane passing through the central axis C11 of each through hole 11. FIG. 2(b) shows a cut surface of holding equipment 10 for optical fiber in the XZ plane passing through the central axis C11 of each through hole 11. The central axis C11 is an axis passing through the center of the through hole 11 when the through hole 11 is cut on a plane perpendicular to the X direction. As shown in FIG. 2(a), each through hole 11 extends linearly along the X direction, for example, and is arranged at equal intervals along the Y direction. When viewed along the X direction in which the central axis C11 extends, each through hole 11 has, for example, a circular shape centered on the central axis C11. The inner diameter D11 of each through hole 11 is constant at each position along the X direction, for example. An opening 11a, which is a first end of each through hole 11, is formed on the front surface 10a. An opening 11b, which is a second end of each through hole 11, is formed on the rear surface 10b.

[0033] 3A is a cross-sectional view of an optical fiber coupling structure 25 equipped with holding equipment for optical fiber 10. FIG. 3B is another cross-sectional view of the optical fiber coupling structure 25. FIG. 4 is a front view of the optical fiber coupling structure 25. FIG. 3A and FIG. 3B show cross sections corresponding to FIG. 2A and FIG. 2B, respectively. As shown in FIG. 3A and FIG. 3B, the optical fiber coupling structure 25 is equipped with the above-mentioned holding equipment for optical fiber 10 and a plurality of optical fibers 20. When each optical fiber 20 is inserted into each through hole 11 of holding equipment for optical fiber 10, it is fixed to the inner surface of each through hole 11 by a cured product 60 of adhesive. In this state, the tip surface 20a (an example of the "tip" in this disclosure) of each optical fiber 20 protrudes forward from the opening 11a of each through hole 11. The cured product 60 of the adhesive is, for example, a cured product of ultraviolet (UV) curable resin. The cured product 60 of the adhesive may be a cured product of thermosetting resin.

[0034] The optical fiber 20 is, for example, an optical fiber that requires rotational alignment (i.e., adjustment of the position around the central axis C20). Each optical fiber 20 is, for example, a multi-core fiber (MCF). Each optical fiber 20 may also be, for example, a polarization-maintaining fiber (PMF). As shown in FIG. 4 , the optical fiber 20 has multiple cores 14a, a cladding 14b that covers the multiple cores 14a, and a coating 14c that surrounds the cladding 14b. At least one of the multiple cores 14a is arranged in a region excluding the central axis C20, i.e., in a region shifted from the central axis C20. The central axis C20 is an axis passing through the center of the optical fiber 20 when the optical fiber 20 is cut along a plane perpendicular to the X direction.

[0035] As shown in Figures 3(a) and 3(b), the optical fiber 20 includes a coating-removed portion 22 and a coating portion 23. The coating-removed portion 22 is a portion of the optical fiber 20 from the tip end face 20a where a predetermined length of the coating 14c (see Figure 4) has been removed. The coating-removed portion 22 includes multiple cores 14a and a clad 14b. In the coating-removed portion 22, the surface of the clad 14b is exposed to the outside. The coating portion 23 is a portion of the optical fiber 20 where the coating 14c remains. The coating portion 23 includes multiple cores 14a, a clad 14b, and the coating 14c. The outer diameter of the coating portion 23 is larger than the outer diameter of the coating-removed portion 22 by the thickness of the coating 14c.

[0036] The coating removal portion 22 includes, for example, an insertion portion 26 that is inserted into and held in the through hole 11, and a protrusion 27 that protrudes from the through hole 11. The insertion portion 26 is, for example, an intermediate portion of the coating removal portion 22 that extends from the portion inside the opening 11b of the through hole 11 to the portion inside the opening 11a of the through hole 11. The protrusion 27 is, for example, a tip portion of the coating removal portion 22 that extends from the portion inside the opening 11a to the tip surface 20a. In other words, the protrusion 27 is, for example, a portion of the coating removal portion 22 that protrudes forward from the front surface 10a on which the opening 11a is formed. The protrusion 27 extends in the X direction outside the through hole 11 so as to move away from the through hole 11.

[0037] The length L27 of the protrusion 27 from the front surface 10a to the tip surface 20a along the X direction corresponds to the distance from the front surface 10a to the front surface 30a of the ferrule 30 along the X direction (see FIG. 7 , described later). The length L26 of the insertion portion 26 from the front surface 10a to the rear surface 10b along the X direction corresponds to the length of the through hole 11 along the X direction. Therefore, the insertion portion 26 is the portion of the coating removal portion 22 that extends from the rear end of the protrusion 27 inside the opening 11a to a position spaced rearward by the length of the through hole 11 along the X direction. The insertion portion 26 is inserted from the opening 11b into the through hole 11 in the X direction and fixed to the inner surface of the through hole 11 by the cured adhesive 60. This holds the insertion portion 26 in the through hole 11. When the insertion portion 26 is held in the through hole 11, the central axis C20 of the insertion portion 26 coincides with, for example, the central axis C11 of the through hole 11 (see FIG. 2A ).

[0038] The through hole 11 is configured to hold the insertion portion 26 rotatably about the central axis C20. The phrase "the through hole 11 is configured to hold the insertion portion 26 rotatably about the central axis C20" means that the inner diameter D11 of the through hole 11 is set to be large enough to allow rotation of the insertion portion 26 about the central axis C20, but small enough to determine the position of the insertion portion 26 in the YZ plane. In this specification, "constant inner diameter" includes both a completely constant inner diameter and an approximately constant inner diameter within a range of manufacturing error, etc. The inner diameter D11 of the through hole 11 is, for example, larger than the outer diameter of the insertion portion 26, i.e., the outer diameter D22 of the coating removal portion 22.

[0039] On the other hand, if the inner diameter D11 of the through hole 11 is too large, the position of the insertion portion 26 relative to the through hole 11 in the YZ plane may not be determined, and the posture of the insertion portion 26 may be significantly tilted inside the through hole 11. If the insertion portion 26 is fixed to the inner surface of the through hole 11 by the cured adhesive 60 while being significantly tilted inside the through hole 11, the tip surface 20a of the optical fiber 20 may be significantly shifted radially outward of the through hole 11. As a result, when inserting the optical fiber coupling structure 25 into the ferrule 30 (see FIG. 8 ), it may be difficult to insert the protruding portion 27 of the optical fiber 20 into the ferrule hole 33. Therefore, in this embodiment, the inner diameter D11 of the through hole 11 is set small so that the tilt of the insertion portion 26 inside the through hole 11 is small. A specific method for setting the inner diameter D11 of the through hole 11 will be described later.

[0040] 3A and 3B, the entire insertion portion 26 is included in the coating removal portion 22. That is, of the coating removal portion 22 and the coating portion 23, only the coating removal portion 22 is inserted into and held in the through hole 11 as the insertion portion 26. However, the entire insertion portion 26 may also be included in the coating portion 23. That is, of the coating removal portion 22 and the coating portion 23, only the coating portion 23 may be inserted into and held in the through hole 11 as the insertion portion 26. Alternatively, a portion of the coating removal portion 22 and a portion of the coating portion 23 may be included in the insertion portion 26. That is, both the coating removal portion 22 and the coating portion 23 may be inserted into and held in the through hole 11 as the insertion portion 26.

[0041] When the above-mentioned optical fiber coupling structure 25 is manufactured, the insertion part 26 of the rotationally aligned optical fiber 20 is fixed inside the through hole 11 by the hardened adhesive 60. Specifically, with the insertion part 26 inserted into the through hole 11, for example, a liquid adhesive is injected into the inside of the through hole 11 from the opening 11b of the rear surface 10b. The liquid adhesive fills the gap between the inner surface of the through hole 11 and the outer surface of the insertion part 26. In this state, the liquid adhesive is hardened by, for example, irradiating ultraviolet light from the outside of holding equipment for optical fiber 10. As a result, an optical fiber coupling structure 25 in which each optical fiber 20 is held by holding equipment for optical fiber 10 is obtained.

[0042] In the manufacturing process of the optical fiber coupling structure 25, it is also possible to prepare another holding equipment for optical fiber and use that holding equipment for optical fiber as a jig from the viewpoint of reducing the positional deviation of the optical fiber 20 with respect to the holding equipment for optical fiber 10. Hereinafter, an example of the manufacturing method of the optical fiber coupling structure 25 will be described with reference to Figs.

[0043] 5(a) to 5(c) are cross-sectional views for explaining an example of a manufacturing method of the optical fiber coupling structure 25. In this manufacturing method, first, as shown in FIG. 5(a), in addition to holding equipment for optical fiber 10 for fixing, auxiliary holding equipment for optical fiber 100 is prepared. The auxiliary holding equipment for optical fiber 100 has, for example, the same configuration as holding equipment for optical fiber 10 for fixing. The auxiliary holding equipment for optical fiber 100 is a jig that is temporarily used to regulate the position of each optical fiber 20 fixed to holding equipment for optical fiber 10 for fixing.

[0044] Next, the auxiliary holding equipment 100 for optical fiber is arranged in the X direction relative to the fixing equipment 10 for optical fiber. Specifically, the rear surface 10b of the auxiliary holding equipment 100 for optical fiber is brought into contact with the front surface 10a of the fixing equipment 10 in the X direction so that each through hole 11 of the auxiliary holding equipment 100 for optical fiber communicates with each through hole 11 of the fixing equipment 10 in the X direction. In this state, for example, the central axis C11 of each through hole 11 of the auxiliary holding equipment 100 for optical fiber coincides with the central axis C11 of each through hole 11 of the fixing equipment 10 when viewed along the X direction. The rear surface 10b of the auxiliary holding equipment 100 for optical fiber may be arranged with a gap in the X direction relative to the front surface 10a of the fixing equipment 10 for optical fiber.

[0045] Next, the optical fiber 20 is inserted in the X direction from the through hole 11 of holding equipment for optical fiber 10 for fixing to the through hole 11 of the auxiliary holding equipment for optical fiber 100. As a result, the insertion part 26 of the optical fiber 20 is inserted into the through hole 11 of holding equipment for optical fiber 10 for fixing, and the protrusion part 27 of the optical fiber 20 is inserted into the through hole 11 of the auxiliary holding equipment for optical fiber 100. Here, it is assumed that the optical fiber 20 is inserted in a state of being tilted with respect to the through hole 11 of holding equipment for optical fiber 10 for fixing. As a result, the insertion part 26 extends in a direction tilted from the central axis C11 inside the through hole 11 of holding equipment for optical fiber 10 for fixing and contacts the inner surface of the through hole 11. The insertion part 26 is bent at the contact position P11 with the inner surface of the through hole 11, and then extends linearly in the X direction along the inner surface of the through hole 11. The protrusion part 27 extends linearly in the X direction along the inner surface of the through hole 11 inside the through hole 11 of the auxiliary holding equipment for optical fiber 100.

[0046] Next, as shown in Fig. 5(b), a liquid adhesive is injected into the through hole 11 of holding equipment for optical fiber 10 for fixing, and the hardened product 60 of the adhesive fixes the insertion part 26 to the inner surface of the through hole 11. At this time, no adhesive is injected into the through hole 11 of the auxiliary holding equipment for optical fiber 100, and the protrusion 27 is not fixed to the inner surface of the through hole 11 of the auxiliary holding equipment for optical fiber 100. Next, as shown in Fig. 5(c), by removing the auxiliary holding equipment for optical fiber 100, an optical fiber coupling structure 25 in which the optical fiber 20 is held by the holding equipment for optical fiber 10 for fixing is obtained.

[0047] In this way, in the manufacturing process of the optical fiber coupling structure 25, when the auxiliary optical fiber holding component 100 is used as a jig for regulating the position of the tip surface 20a of the protrusion 27 of the optical fiber 20 protruding from the through hole 11 of the fixing optical fiber holding component 10, the position of the tip surface 20a of the protrusion 27 is regulated by the inner surface of the through hole 11 of the auxiliary optical fiber holding component 100, thereby reducing the position of the tip surface 20a of the protrusion 27 from shifting significantly radially outward from the through hole 11.

[0048] Furthermore, by arranging a plurality of holding equipment for optical fiber 10,100 in the X direction in this way, the total length of these holding equipment for optical fiber 10,100 in the X direction can be increased. The longer the total length of holding equipment for optical fiber 10,100, the smaller the tilt that can occur in the insertion part 26 of the optical fiber 20 inserted into the through hole 11 of holding equipment for optical fiber 10,100. As a result, when inserting the optical fiber 20 held by holding equipment for optical fiber 10 for fixing into the inside of the ferrule 30, the protrusion 27 can be inserted more reliably into the ferrule hole 33 without the tip face 20a of the optical fiber 20 strongly hitting against the inner surface of the ferrule hole 33. This can more reliably reduce the large load on the optical fiber 20, and can increase the reliability of the optical fiber 20.

[0049] Furthermore, when the auxiliary optical fiber holding equipment 100 is brought into contact with the fixing optical fiber holding equipment 10 in the X direction so that the through-hole 11 of the auxiliary optical fiber holding equipment 100 communicates with the through-hole 11 of the fixing optical fiber holding equipment 10 in the X direction, the protrusion 27 of the optical fiber 20 can be easily and surely inserted into the through-hole 11 of the auxiliary optical fiber holding equipment 100 when inserting the optical fiber 20 from the through-hole 11 of the fixing optical fiber holding equipment 10 to the through-hole 11 of the auxiliary optical fiber holding equipment 100, compared to the case where the auxiliary optical fiber holding equipment 100 is arranged with a gap from the fixing optical fiber holding equipment 10.

[0050] 5(a) to 5(c) illustrate the case where one auxiliary holding equipment for optical fiber 100 is used as a jig. However, the number of auxiliary holding equipment for optical fiber 100 may be two or more. For example, when two auxiliary holding equipment for optical fiber are used as a jig, two auxiliary holding equipment for optical fiber may be arranged in front or behind the holding equipment for optical fiber 10 for fixing in the X direction. Or, two auxiliary holding equipment for optical fiber may be arranged on both sides of the holding equipment for optical fiber 10 for fixing in the X direction. In this case, an injection hole for injecting adhesive may be formed on the upper surface 10c of the holding equipment for optical fiber 10 for fixing. The injection hole may extend from the upper surface 10c in the Z direction and communicate with the through hole 11. In this case, the optical fiber 20 can be fixed to the inner surface of the through hole 11 by the adhesive injected into the through hole 11 from the upper surface 10c through the injection hole.

[0051] By arranging a plurality of auxiliary holding equipment for optical fiber in the X direction, the overall length of these holding equipment for optical fiber in the X direction can be made longer. Accordingly, the tilt that may occur in the insertion part 26 of the optical fiber 20 inserted into the through hole 11 of these holding equipment for optical fiber can be made smaller. As a result, when inserting the optical fiber 20 held by the holding equipment for optical fiber 10 for fixing into the inside of the ferrule 30, the tip surface 20a of the optical fiber 20 does not hit the inner surface of the ferrule hole 33 strongly, and the protrusion 27 can be inserted more reliably into the ferrule hole 33.

[0052] Fig. 6 is an exploded perspective view of an optical connector 2 including the above-described optical fiber coupling structure 25. Fig. 7 is a perspective view of the optical connector 2 of Fig. 6. The optical connector 2 includes, for example, the above-described optical fiber coupling structure 25 and a ferrule 30. As shown in Figs. 6 and 7, the ferrule 30 has, for example, a substantially rectangular parallelepiped appearance. The optical fiber coupling structure 25 is inserted into the ferrule 30 and fixed therein. The optical connector 2 may include, for example, two optical fiber coupling structures 25. In this case, the two optical fiber coupling structures 25 may be inserted into the ferrule 30 in a state where they are stacked in the Z direction with their top surfaces 10c, 10c facing each other.

[0053] FIG. 8A is a cross-sectional view of the optical connector 2. FIG. 8B is another cross-sectional view of the optical connector 2. As shown in FIGS. 8A and 8B, the ferrule 30 has a front surface 30a located at the front end in the X direction and a rear surface 30b located at the rear end in the X direction. The front surface 30a is, for example, flush with the tip surfaces 20a of the optical fibers 20 without any steps. The rear surface 30b has an opening 31 capable of receiving the optical fiber coupling structure 25. In FIGS. 6 and 7, a pair of guide holes 34 are formed in the ferrule 30, but in FIG. 8B, the pair of guide holes 34 are omitted for convenience. The pair of guide holes 34 are holes that penetrate the ferrule 30 in the X direction from the front surface 30a to the rear surface 30b.

[0054] The ferrule 30 has an accommodating hole 32 and a plurality of ferrule holes 33 therein. The accommodating hole 32 is a hole extending in the X direction from the opening 31. The accommodating hole 32 holds the optical fiber coupling structure 25 introduced through the opening 31. The accommodating hole 32 includes, for example, an inner surface 32a, a pair of inner surfaces 32b, 32b, an inner surface 32c, an inner surface 32d, and an inner surface 32e. The inner surface 32a extends, for example, along the XY plane. The pair of inner surfaces 32b, 32b extend, for example, along the XZ plane and are disposed on both sides of the inner surface 32a in the Y direction. The pair of inner surfaces 32b, 32b are formed, for example, perpendicular to the inner surface 32a. The inner surface 32c extends along the YZ plane and extends upward from the inner surface 32a in the Z direction. The inner surface 32c faces the opening 31 in the X direction. The inner surface 32c is formed, for example, perpendicular to the inner surface 32a.

[0055] The inner surface 32d extends, for example, along the YZ plane and is recessed further forward than the inner surface 32c. The inner surface 32d extends, for example, parallel to the inner surface 32c. The inner surface 32e extends along the XY plane so as to connect the inner surfaces 32c and 32d in the X direction. For example, a plurality of V-grooves 32f corresponding to the plurality of ferrule holes 33 are formed on the inner surface 32e.

[0056] As shown in FIG. 8B , the multiple ferrule holes 33 penetrate in the X direction from the inner surface 32 d to the front surface 30 a. The multiple ferrule holes 33 are aligned in a line in the Y direction to correspond to the multiple optical fibers 20 aligned in a line in the Y direction. The protrusion 27 of each optical fiber 20 extending forward from the optical fiber coupling structure 25 is inserted into each ferrule hole 33. The inner diameter D33 of the ferrule hole 33 is, for example, larger than the outer diameter of the protrusion 27, i.e., the outer diameter D22 of the coating-removed portion 22. As shown in FIG. 8A , a window 35 for injecting adhesive is formed on the top surface of the ferrule 30. Although the cured adhesive is omitted in FIGS. 8A and 8B , the cured adhesive may be the same as the cured adhesive 60 described above.

[0057] When the optical fiber coupling structure 25 is placed in the receiving hole 32, the lower surface 10d of the optical fiber coupling structure 25 contacts the inner surface 32a. This determines the position of the optical fiber coupling structure 25 in the Z direction relative to the ferrule 30. Furthermore, as shown in Figure 8(b), the side surfaces 10e and 10f of the optical fiber coupling structure 25 contact the pair of inner surfaces 32b, 32b, respectively. This determines the position of the optical fiber coupling structure 25 in the Y direction relative to the ferrule 30.

[0058] In this state where the position of the optical fiber coupling structure 25 in the YZ plane relative to the ferrule 30 is determined, the central axis C11 of each through hole 11 of holding equipment for optical fiber 10 coincides with the central axis C33 of each ferrule hole 33 when viewed along the X direction. Furthermore, the front surface 10a of the optical fiber coupling structure 25 abuts against the inner surface 32c in the X direction, thereby determining the position of the optical fiber coupling structure 25 in the X direction relative to the ferrule 30. Then, adhesive is injected from the window 35, and the optical fiber coupling structure 25 is fixed to the ferrule 30 by the hardened adhesive. In this way, the optical connector 2 is obtained.

[0059] 9 is a perspective view showing an optical coupling structure 1 including a first optical connector 2a and a second optical connector 2b as the optical connectors 2. In the optical coupling structure 1, the front surface 30a of the first optical connector 2a and the front surface 30a of the second optical connector 2b face each other in the X direction with a gap therebetween. In this state, a pair of guide pins 40 are fitted into a pair of guide holes 34 of the first optical connector 2a and a pair of guide holes 34 of the second optical connector 2b. This defines the positions of the first optical connector 2a and the second optical connector 2b in the YZ plane.

[0060] A spacer 50 is disposed between the front surface 30a of the first optical connector 2a and the front surface 30a of the second optical connector 2b. The spacer 50 is a plate-like member having an opening 50a. The opening 50a allows a plurality of optical paths extending between the first optical connector 2a and the second optical connector 2b to pass through. The spacer 50 abuts against the front surface 30a of the first optical connector 2a and the front surface 30a of the second optical connector 2b in the X direction, thereby defining a gap between the first optical connector 2a and the second optical connector 2b in the X direction.

[0061] Next, with reference to Fig. 10 and Fig. 11, a method for setting the inner diameter D11 of the through hole 11 of the holding equipment for optical fiber 10 will be described in detail. Fig. 10 and Fig. 11 are diagrams for explaining a method for setting the inner diameter D11 of the through hole 11. In Fig. 10 and Fig. 11, the outer diameter D22 of the coating removal part 22 of the optical fiber 20 is represented by "A", the inner diameter D11 of the through hole 11 is represented by "B", the inner diameter D33 of the ferrule hole 33 is represented by "C", the length of the through hole 11 along the X direction, i.e., the length L26 of the insertion part 26 along the X direction is represented by "D", and the length L27 of the protrusion 27 along the X direction is represented by "d".

[0062] 10 shows a cross section of the optical fiber coupling structure 25 when the insertion portion 26 of the optical fiber 20 is tilted to the maximum within the through hole 11 in a state where the central axis C11 of the through hole 11 coincides with the central axis C33 of the ferrule hole 33 as viewed along the X direction. The state where the central axis C11 of the through hole 11 coincides with the central axis C33 of the ferrule hole 33 as viewed along the X direction refers to a state where the through hole 11 and the ferrule hole 33 are aligned in the X direction so that an extension of the central axis C11 coincides with the central axis C33. The state where the insertion portion 26 is tilted to the maximum refers to a state where the angle θ between the central axis C20 of the insertion portion 26 inserted into the through hole 11 and the central axis C11 of the through hole 11 is maximized. For example, the angle θ is maximized when the insertion portion 26 is in contact with the upper end of the opening 11a and the lower end of the opening 11b.

[0063] As shown in Fig. 10, the inner diameter B is represented by the sum of the lengths L1 and L2. The length L1 indicates the length in the Z direction of the region inside the opening 11a that is occupied by the insertion portion 26. The length L2 indicates the length in the Z direction of the region inside the opening 11a that is not occupied by the insertion portion 26. Since the length L1 is geometrically represented by the following formula (1), the length L2 is represented by the following formula (2). Therefore, the following relational expression (3) is obtained with respect to the angle θ.

[0064] Next, if the distance in the X direction from the front surface 10a to the upper end of the tip surface 20a is represented as L3, then distance L3 is geometrically expressed by the following formula (4). Therefore, if the amount of deviation of the tip surface 20a from the inner surface of the through hole 11 in the Z direction is represented as L4, then deviation L4 is geometrically expressed by the following formula (5). If the amount of deviation between the inner diameter B and the inner diameter C is represented as L5, then deviation L5 is expressed by the following formula (6). In order to insert the optical fiber 20 into the ferrule hole 33 so that the tip surface 20a does not contact the inner surface S33 of the ferrule hole 33, deviation L4 of the tip surface 20a only needs to be smaller than deviation L5. Therefore, deviation L5 indicates the allowable range of deviation L4 for preventing the tip surface 20a from contacting the inner surface S33 of the ferrule hole 33. That is, the condition for inserting the optical fiber 20 into the ferrule hole 33 without bringing the tip face 20a into contact with the inner surface S33 of the ferrule hole 33 is L4<L5. When this condition is expressed using equations (5) and (6), the following equation (7) is obtained.

[0065] Substituting equation (3) into equation (7) above, the condition that the inner diameter B must satisfy is expressed as the following equation (8). By setting an upper limit for the inner diameter B in this manner, it becomes possible to insert the optical fiber 20 into the ferrule hole 33 without the tip end face 20a coming into contact with the inner surface S33 of the ferrule hole 33. If the inner diameter B is not constant at each position of the through hole 11 along the X direction, it is sufficient that the maximum value of the inner diameter B satisfies the upper limit of the inner diameter B shown in equation (8). The maximum value of the inner diameter B may be smaller than the maximum value of the inner diameter C, for example. For example, if the ferrule hole 33 has a diameter-expanding portion that expands as it approaches the inner surface 32c, the inner diameter of the opening of the ferrule hole 33 at the inner surface 32c becomes maximum. Therefore, the maximum value of the inner diameter C in this case is the inner diameter of the opening of the ferrule hole 33 at the inner surface 32c. Regarding the outer diameter A in formula (7), when the outer diameter A is not constant at each position of the coating removal portion 22 along the X direction, it is sufficient that the maximum value of the outer diameter A satisfies the condition for the lower limit of the inner diameter B shown in formula (8). In other words, it is sufficient that the minimum value of the inner diameter B is larger than the maximum value of the outer diameter A.

[0066] As an example, if the outer diameter A is 125 μm, the inner diameter C is 200 μm, the length D is 1.5 mm, and the length d is 6.5 mm, substituting these values ​​into equation (8) yields the relationship 125 μm<B<132.8 μm. However, the angle θ is considered to be infinitesimally small, and is approximated as sin θ≈0 and cos θ≈1. For example, when the inner diameter B is 130 μm, the inventors have confirmed that the optical fiber 20 can be inserted into the ferrule hole 33 without the tip end face 20a coming into contact with the inner surface S33 of the ferrule hole 33. Therefore, the maximum value of the inner diameter B may be, for example, smaller than 132.8 μm.

[0067] By setting the inner diameter B to satisfy the condition of formula (7), the position of the tip face 20a can be limited so that the tip face 20a does not contact the inner surface S33 of the ferrule hole 33. As a result, as shown in FIG. 11 , the tip face 20a is located more inward than the inner surface S33 of the ferrule hole 33 when viewed along the X direction. FIG. 11 shows a front view of the front surface 10a of the optical fiber coupling structure 25 of FIG. 10 . In FIG. 11 , the inner surface S33 of the ferrule hole 33 is indicated by a two-dot chain line. The tip face 20a being located more inward than the inner surface S33 when viewed along the X direction means that the entire tip face 20a is contained within the area inside the inner surface S33 when viewed along the X direction. The tip face 20a may be separated from the inner surface S33 without overlapping with the inner surface S33 when viewed along the X direction.

[0068] 3B. The relationship between the inner diameter B and the length d shown in the above formula (8) can be explained as follows. For example, when the length d of the protrusion 27 is relatively short (i.e., when holding equipment 10 for optical fiber is placed near the ferrule hole 33), the inclination of the protrusion 27 is reduced, so the inner diameter B can be made larger. If the inner diameter B can be made larger, it becomes easier to insert the protrusion 27 into the ferrule hole 33 without the tip face 20a of the optical fiber 20 hitting hard against the inner surface S33 of the ferrule hole 33. Furthermore, when the inner diameter B is large, it becomes possible to relax the manufacturing precision of the through hole 11 of holding equipment for optical fiber 10. On the other hand, when the length d of the protrusion 27 is relatively long (i.e., when holding equipment 10 for optical fiber is placed at a position far from the ferrule hole 33), the inclination of the protrusion 27 becomes large, so it is required to make the inner diameter B smaller. However, by making the length d of the protrusion 27 longer, it becomes possible to distribute the bending stress acting on the protrusion 27 when inserting the optical fiber 20 into the through hole 11.

[0069] Specific numerical examples of the relationship between the inner diameter B and the length d are shown below. In the following example, the outer diameter A=125 μm, the inner diameter C=200 μm, the length D=1.5 mm, sin θ≒0, and cos θ≒1. The total length of the ferrule 30 is 8 mm, and the total length of the ferrule hole 33 is 1 mm. Under this condition, when the length d=1 mm, the holding equipment for optical fiber 10 is adjacent to the ferrule hole 33, and the length d of the protruding part 27 is equal to the total length of the ferrule hole 33. In this case, by using formula (8), it is possible to derive 157.1 μm as the upper limit of the maximum value of the inner diameter B. When the length d of the protruding part 27 is shortened in this way, as described above, the effect of reducing the risk of the optical fiber 20 coming into contact with the inner surface S33 of the ferrule hole 33 when inserting the holding equipment for optical fiber 10 into the ferrule 30 and the effect of loosening the manufacturing precision of the through hole 11 of the holding equipment for optical fiber 10 are remarkably obtained.

[0070] Next, under the above conditions, when the length d=6.5 mm, holding equipment 10 for optical fiber is placed at the position inside the ferrule 30 that is the farthest from the ferrule hole 33. In this case, using formula (8), it is possible to derive 132.8 μm as the upper limit of the maximum value of the inner diameter B. In this way, when the length d of the protrusion 27 is made longer, it is possible to obtain a significant effect of dispersing the bending stress applied to the protrusion 27 when the optical fiber 20 is inserted into the through hole 11. Next, under the above conditions, when the length d=4 mm, holding equipment 10 for optical fiber is placed at the center inside the ferrule 30. In this case, using formula (8), it is possible to derive 136.8 μm as the upper limit of the maximum value of the inner diameter B. By setting the length d of the protrusion 27 in this way, it is possible to effectively obtain the effect of reducing the risk of the optical fiber 20 coming into contact with the inner surface S33 of the ferrule hole 33 when inserting holding equipment 10 for optical fiber into the inside of the ferrule 30, the effect of being able to relax the manufacturing precision of the through hole 11 of holding equipment for optical fiber 10, and the effect of dispersing the bending stress to the protrusion 27 when inserting the optical fiber 20 into the through hole 11. Based on the above, the maximum value of the inner diameter B may be, for example, smaller than 157.1 μm, may be smaller than 136.8 μm, or may be smaller than 132.8 μm.

[0071] The effects obtained by the optical fiber holding equipment 10, the optical fiber coupling structure 25, the optical connector 2, the optical coupling structure 1, and the manufacturing method of the optical fiber coupling structure 25 according to the present embodiment described above will be explained together with the problems of the comparative example.

[0072] 12(a) to (c) are views for explaining the problems of holding equipment for optical fiber 110 according to a comparative example. The holding equipment for optical fiber 110 has a through hole 111 for holding an optical fiber 120. As shown in FIG. 12(a), when the inner diameter of the through hole 111 is set relatively large, the optical fiber 120 may be inserted into the through hole 111 in a state of being greatly tilted, and in that state the optical fiber 120 may be fixed to the inner surface of the through hole 111 by the hardened product 160 of the adhesive. As a result, the tip surface 120a of the optical fiber 120 may be largely deviated to the outside of the through hole 111. In this case, even if the position of the holding equipment for optical fiber 110 with respect to the ferrule 130 is adjusted so that the central axis C111 of the through hole 111 and the central axis C133 of the ferrule hole 133 coincide with each other when viewed along the X direction, it is assumed that the tip surface 120a may hit the wall surface around the ferrule hole 133 when inserting the holding equipment for optical fiber 110 into the ferrule 130.

[0073] Therefore, as shown in Fig. 12(b), it is conceivable to shift the holding equipment for optical fiber 110 in the Z direction relative to the ferrule 130 until the tip surface 120a does not hit the wall surface around the ferrule hole 133, and then, as shown in Fig. 12(c), to forcibly insert the optical fiber 120 into the ferrule hole 133 while pressing it against the inner surface of the ferrule hole 133. However, in this case, there is a risk that a large load will be applied to the optical fiber 120 due to the optical fiber 120 coming into strong contact with the inner surface of the ferrule hole 133. Such a load may cause problems such as damage to the optical fiber 120 or a decrease in optical transmission characteristics, which may be a factor in reducing the reliability of the optical fiber 120.

[0074] 10 and 11, in a state where the central axis C11 of the through hole 11 coincides with the central axis C33 of the ferrule hole 33 when viewed along the X direction, when the central axis C20 of the insertion part 26 of the optical fiber 20 is inclined to the maximum extent with respect to the central axis C11 of the through hole 11 inside the through hole 11, the tip surface 20a of the protrusion 27 is located inside the inner surface S33 of the ferrule hole 33 when viewed along the X direction. In this case, no matter what angle the insertion part 26 is inclined at inside the through hole 11, when inserting the holding equipment for optical fiber 10 into the ferrule 30, the protrusion 27 can be reliably inserted into the ferrule hole 33 without the tip surface 20a strongly hitting against the inner surface S33 of the ferrule hole 33 or the inner surface 32d around the ferrule hole 33. This can reduce the application of a large load to the optical fiber 20. As a result, the occurrence of problems such as damage to the optical fiber 20 or deterioration of optical transmission characteristics can be reduced. Therefore, according to this embodiment, the reliability of the optical fiber 20 can be improved.

[0075] As in this embodiment, the maximum value of the inner diameter D11 of the through hole 11 may be smaller than the maximum value of the inner diameter D33 of the ferrule hole 33. By reducing the maximum value of the inner diameter D11 of the through hole 11 in this way, the inclination of the insertion part 26 inside the through hole 11 can be kept small. Accordingly, the deviation of the tip face 20a of the protruding part 27 from the through hole 11 can be kept small. As a result, when inserting holding equipment 10 for optical fiber into the inside of the ferrule 30, it becomes possible to insert the protruding part 27 into the ferrule hole 33 more reliably without the tip face 20a hitting hard against the inner surface S33 of the ferrule hole 33 or the like.

[0076] As in this embodiment, only the coating removal part 22 may be inserted into the through hole 11 as the insertion part 26. In this case, the maximum value of the inner diameter D11 of the through hole 11 can be made small in accordance with the outer diameter D22 of the coating removal part 22, so the inclination of the insertion part 26 inside the through hole 11 can be kept small. Accordingly, the deviation of the tip face 20a of the protruding part 27 from the through hole 11 can be kept small. As a result, when inserting holding equipment for optical fiber 10 into the inside of the ferrule 30, the tip face 20a does not hit hard against the inner surface S33 of the ferrule hole 33, and the protruding part 27 can be inserted more reliably into the ferrule hole 33.

[0077] As in this embodiment, the optical fiber 20 may include at least one core 14a in a region shifted from the central axis C20 of the optical fiber 20. The through hole 11 may be configured to rotatably hold the insertion portion 26 around the central axis C20 of the insertion portion 26. In this case, the rotational position of the insertion portion 26 of the optical fiber 20 can be adjusted. During this adjustment, the insertion portion 26 of the optical fiber 20 is likely to tilt. Therefore, the above-mentioned configuration can effectively achieve the above-mentioned effects.

[0078] The optical fiber holding components, optical fiber coupling structures, optical connectors, optical coupling structures, and methods for manufacturing optical fiber coupling structures of the present disclosure are not limited to the above-described embodiments, and can be modified as appropriate within the scope of the claims.

[0079] [Modification 1] Fig. 13(a) is a cross-sectional view of an optical connector 2A according to Modification 1. Fig. 13(b) is another cross-sectional view of the optical connector 2A. The optical connector 2A differs from the optical connector 2 described above in that only the coating portion 23 of the optical fiber 20 is inserted into the through-hole 11A of holding equipment for optical fiber 10A as an insertion portion 26A. As shown in Fig. 13(a), the inner diameter D11A of the through-hole 11A is set larger than the outer diameter D23 of the coating portion 23. The coating removal portion 22 and the end of the coating portion 23 protrude to the outside from the through-hole 11A as a protrusion 27A. The receiving hole 32A of the ferrule 30A further includes an inner surface 32g in addition to the configuration of the receiving hole 32 described above. The inner surface 32g is located between the inner surface 32e and the inner surface 32a in the X direction and extends along the XY plane. The inner surface 32g forms a step recessed in the Z direction relative to the inner surface 32e. The inner surface 32g faces the end of the covering portion 23 included in the protruding portion 27A in the Z direction.

[0080] 14 and 15 are diagrams for explaining a method for setting the inner diameter D11A of the through hole 11A. In Figures 14 and 15, the outer diameter D22 of the coating-removed portion 22 of the optical fiber 20 is represented by "A," the inner diameter D11A of the through hole 11A is represented by "B," the inner diameter D33 of the ferrule hole 33 is represented by "C," the length of the through hole 11A along the X direction, i.e., the length L26 of the insertion portion 26A along the X direction, is represented by "D," the length L27 of the protrusion 27A along the X direction is represented by "d," and the outer diameter D23 of the coating portion 23 of the optical fiber 20 is represented by "E."

[0081] 14 shows a cross section of the optical fiber coupling structure 25A when the insertion portion 26A of the optical fiber 20 is tilted to its maximum within the through hole 11A, with the central axis C11 of the through hole 11A aligned with the central axis C33 of the ferrule hole 33 as viewed along the X direction. As shown in FIG. 14 , the inner diameter B is expressed as the sum of the lengths L1 and L2. Since the lengths L1 and L2 are expressed as in the above-described formulas (1) and (2), respectively, the relational expression (3) above is obtained with respect to the angle θ. If the distance in the X direction from the front surface 10a to the upper end of the tip surface 20a is expressed as L3, the distance L3 is expressed by the above-described formula (4). If the amount of deviation of the tip surface 20a from the inner surface of the through hole 11A in the Z direction is expressed as L4, the deviation amount L4 is expressed by the above-described formula (5).

[0082] Next, if the amount of deviation between the outer diameter E of the coated portion 23 and the outer diameter A of the coating-removed portion 22 is represented by L5, the amount of deviation L5 is expressed by the following equation (9), and therefore the length L6 is geometrically expressed by the following equation (10). Next, if the amount of deviation in the Z direction of the tip surface 20a from the inner surface of the through hole 11A is represented by L7, the amount of deviation L7 can be obtained by subtracting the length L6 from the amount of deviation L4, and therefore the following equation (11) is obtained. Then, if the amount of deviation between the inner diameter B and the inner diameter C is represented by L8, the amount of deviation L8 is expressed by the following equation (12).

[0083] In order to insert the optical fiber 20 into the ferrule hole 33 so that the tip face 20a does not come into contact with the inner surface S33 of the ferrule hole 33, it is sufficient that the amount of deviation L7 of the tip face 20a is smaller than the amount of deviation L8. Therefore, the amount of deviation L8 indicates the allowable range of the amount of deviation L7 for the tip face 20a not to come into contact with the inner surface S33 of the ferrule hole 33. The condition for inserting the optical fiber 20 into the ferrule hole 33 without the tip face 20a coming into contact with the inner surface S33 of the ferrule hole 33 is L7<L8. Expressing this condition using equations (11) and (12), the following equation (13) is obtained.

[0084] Substituting equation (3) into equation (13) above, the condition that the inner diameter B must satisfy is expressed as the following equation (14). Setting an upper limit for the inner diameter B in this manner makes it possible to insert the optical fiber 20 into the ferrule hole 33 without the tip face 20a coming into contact with the inner surface S33 of the ferrule hole 33. When the inner diameter B is not constant at each position of the through hole 11A along the X direction, it is sufficient that the maximum value of the inner diameter B satisfies the upper limit condition for the inner diameter B shown in equation (14). The maximum value of the inner diameter B may be smaller than 216.6 μm, for example. Regarding the outer diameter E in equation (14), when the outer diameter E is not constant at each position of the coating 23 along the X direction, it is sufficient that the maximum value of the outer diameter E satisfies the lower limit condition for the inner diameter B shown in equation (14). In other words, it is sufficient that the minimum value of the inner diameter B is equal to or greater than the maximum value of the outer diameter E. When only the coating 23 is inserted into the through hole 11A as in this modification, even if the coating 23 is in contact with the inner surface of the through hole 11A, a large load is unlikely to be applied to the optical fiber 20. Therefore, the minimum value of the inner diameter B may be the same as the maximum value of the outer diameter E.

[0085] By setting the inner diameter B to satisfy the condition of formula (14), the position of the tip face 20a can be limited so that the tip face 20a does not contact the inner surface S33 of the ferrule hole 33. As a result, as shown in FIG. 15 , the tip face 20a is located more inward than the inner surface S33 of the ferrule hole 33 when viewed along the X direction. FIG. 15 shows a front view of the front surface 10a of the optical fiber coupling structure 25A of FIG. 14 . In FIG. 15 , the inner surface S33 of the ferrule hole 33 is indicated by a two-dot chain line. The tip face 20a being located more inward than the inner surface S33 when viewed along the X direction means that the entire tip face 20a is contained within the area inside the inner surface S33 when viewed along the X direction. The tip face 20a may be separated from the inner surface S33 without overlapping with the inner surface S33 when viewed along the X direction.

[0086] Specific numerical examples of the relationship between the inner diameter B and the length d are shown below. In the following example, the outer diameter A=125 μm, the inner diameter C=230 μm, the length D=1.5 mm, the outer diameter E=200 μm, sin θ≒0, and cos θ≒1. The total length of the ferrule 30A is 8 mm, and the total length of the ferrule hole 33 is 1 mm. Under these conditions, if the length d=6.5 mm, the holding equipment 10A for optical fiber is placed at the position inside the ferrule 30A that is the farthest from the ferrule hole 33. In this case, by using formula (14), the upper limit of the maximum value of the inner diameter B can be derived as 210.9 μm. In this way, if the length d of the protrusion 27A is increased, the effect of dispersing the bending stress applied to the protrusion 27A when the optical fiber 20 is inserted into the through hole 11A can be significantly obtained.

[0087] Next, under the above conditions, when the length d=4 mm, the holding equipment for optical fiber 10A is placed at the center inside the ferrule 30A. In this case, by using formula (14), 216.6 μm can be derived as the upper limit of the maximum value of the inner diameter B. By setting the length d of the protrusion 27A in this way, it is possible to effectively obtain the effects of reducing the risk of the optical fiber 20 contacting the inner surface S33 of the ferrule hole 33 when inserting the holding equipment for optical fiber 10A into the ferrule 30A, the effect of loosening the manufacturing precision of the through hole 11A of the holding equipment for optical fiber 10A, and the effect of dispersing the bending stress to the protrusion 27A when inserting the optical fiber 20 into the through hole 11A. Based on the above, the maximum value of the inner diameter B may be smaller than 210.9 μm or 216.6 μm, for example.

[0088] Even with this configuration, the same effects as those of the above-described embodiment can be achieved. Furthermore, in this modification, only the covering portion 23 is inserted into the through hole 11A as the insertion portion 26A. In this case, the maximum inner diameter D11A of the through hole 11A is set large to match the outer diameter D23 of the covering portion 23. Accordingly, the allowable range of deviation of the leading end surface 20a of the protruding portion 27A from the through hole 11A to prevent the leading end surface 20a from contacting the inner surface of the ferrule hole 33 is narrowed. As is clear from the above-described formula (12), the larger the inner diameter B, the smaller the deviation amount L8, which is the allowable range of the deviation amount L7. As a result, when the protruding portion 27A is inserted into the ferrule hole 33, the leading end surface 20a is likely to abut against the inner surface S33 of the ferrule hole 33, for example. In contrast, according to this modified example, regardless of the angle at which the insertion portion 26A is tilted inside the through hole 11A, the protrusion 27A can be reliably inserted into the ferrule hole 33 without the tip surface 20a strongly hitting the inner surface S33 of the ferrule hole 33, etc., thereby more effectively reducing the large load on the optical fiber 20.

[0089] [Modification 2] Fig. 16a is a cross-sectional view of an optical connector 2B according to modification 2. Fig. 16b is a plan view of holding equipment for optical fiber 10B that the optical connector 2B has. The difference between the optical connector 2B and the optical connector 2 described above is the configuration of holding equipment for optical fiber 10B. As shown in Fig. 16a and Fig. 16b, holding equipment for optical fiber 10B has a support part 12 that supports coating removal part 22 of a plurality of optical fibers 20, and a support part 13 that supports coating part 23 of a plurality of optical fibers 20.

[0090] The support portion 12 includes a plurality of through holes 11B into which the coating-removed portions 22 of the plurality of optical fibers 20 are respectively inserted as insertion portions 26. Each through hole 11B includes, for example, a constant diameter portion 11c and an expanded diameter portion 11d. The constant diameter portion 11c extends linearly in the X direction from the front surface 10a toward the rear surface 10b. The inner diameter of the constant diameter portion 11c is constant at each position along the X direction of the constant diameter portion 11c. The expanded diameter portion 11d extends linearly in the X direction from the constant diameter portion 11c to the support portion 13. The inner diameter of the expanded diameter portion 11d is set to gradually increase from the constant diameter portion 11c toward the support portion 13 in the X direction.

[0091] The constant diameter portion 11c has an inner diameter that allows the coating removal portion 22 of the optical fiber 20 to be inserted therein. The constant diameter portion 11c is configured to rotatably hold the coating removal portion 22 around the central axis C20 of the optical fiber 20. The constant diameter portion 11c being configured to rotatably hold the coating removal portion 22 around the central axis C20 means that the inner diameter of the constant diameter portion 11c is set to be large enough to allow rotation of the coating removal portion 22 around the central axis C20, and small enough to allow the position of the coating removal portion 22 in the YZ plane to be defined.

[0092] The support portion 13 is disposed between the support portion 12, in which the multiple through holes 11B are formed, and the rear surface 10b in the X direction. The support portion 13 supports the coating portion 23 of the optical fiber 20 disposed outside the through holes 11B. The support portion 13 includes, for example, multiple fixing holes 13a that penetrate from the rear surface 10b in the X direction and communicate with each of the multiple through holes 11B. Each fixing hole 13a extends linearly in the X direction from the rear surface 10b toward the constant diameter portion 11c. The fixing holes 13a have an inner diameter that allows the coating portion 23 of the optical fiber 20 to be inserted therein. The fixing holes 13a are configured to hold the coating portion 23 rotatably around the central axis C20. Therefore, the inner diameter of the fixing holes 13a is set to be large enough to allow rotation of the coating portion 23 around the central axis C20, but small enough to determine the position of the coating portion 23 in the YZ plane. The inner diameter of the fixing holes 13a is constant at each position along the X direction. The inner diameter of the fixing hole 13 a may be equal to or larger than the outer diameter of the covering portion 23 .

[0093] Even in this form, it is possible to obtain the same effect as the above-mentioned embodiment. Furthermore, in this modification, holding equipment 10B has supporting part 13 which can support coating part 23. In this case, by supporting coating part 23 of optical fiber 20 by supporting part 13 of holding equipment 10B, it is possible to suppress tilt of insertion part 26 in through hole 11B more small. Accordingly, it is possible to suppress deviation of tip face 20a of protrusion 27 from through hole 11B more small. As a result, when inserting holding equipment 10B into ferrule 30, it is possible to insert protrusion 27 into ferrule hole 33 more reliably without hitting tip face 20a hard against inner surface S33 of ferrule hole 33 etc.

[0094] In this modification, the through hole 11B includes a constant diameter portion 11c and an expanded diameter portion 11d. In this case, when the optical fiber 20 is inserted into the through hole 11B, the tip surface 20a of the optical fiber 20 is guided into the constant diameter portion 11c by the expanded diameter portion 11d, thereby reducing strong contact of the tip surface 20a of the optical fiber 20 with the inner surface of the through hole 11B, etc. This more reliably reduces the application of a large load to the optical fiber 20.

[0095] Fig. 17(a) is a perspective view of holding equipment for optical fiber 10C which is another example of holding equipment for optical fiber 10B. As shown in Fig. 17(a), holding equipment for optical fiber 10C includes a support part 13A including one fixing hole 13b instead of the support part 13 including multiple fixing holes 13a. The fixing hole 13b has an oval shape that includes all the through holes 11B when viewed along the X direction. The fixing hole 13b communicates with multiple through holes 11B in the X direction. Coating parts 23 of optical fibers 20 are inserted together into the fixing hole 13b.

[0096] Fig. 17(b) is a perspective view of holding equipment for optical fiber 10D which is yet another example of holding equipment for optical fiber 10B. As shown in Fig. 17(b), holding equipment for optical fiber 10D includes a supporting part 13B including a supporting surface 13c instead of the supporting part 13 including a plurality of fixing holes 13a. The supporting surface 13c is, for example, a plane along the XY plane, and forms a step with respect to the upper surface 10c. The supporting surface 13c is arranged at a position shifted toward the lower surface 10d side from the through hole 11B in the Z direction. The supporting surface 13c supports the covering part 23 arranged outside the through hole 11B in the Z direction. Even with the forms of Fig. 17(a) and (b), the same effect as the above-mentioned holding equipment for optical fiber 10B can be achieved.

[0097] [Modification 3] Fig. 18a is a cross-sectional view of an optical connector 2C according to modification 3. Fig. 18b is a plan view of holding equipment for optical fiber 10E included in the optical connector 2C. The optical connector 2C is different from the optical connector 2 described above in that holding equipment for optical fiber 10E includes a plurality of injection holes 15. As shown in Fig. 18a, each injection hole 15 is a hole extending from the upper surface 10c in the Z direction. As shown in Fig. 18b, each injection hole 15 is arranged in a row in the Y direction corresponding to each through hole 11. Each injection hole 15 is, for example, circular when viewed along the Z direction, and is arranged to overlap with the through hole 11 in the Z direction. Each injection hole 15, for example, penetrates linearly from the upper surface 10c to each through hole 11 in the Z direction, and is individually connected to each through hole 11. Each injection hole 15 being individually connected to each through hole 11 means that one injection hole 15 is connected to one through hole 11, and one injection hole 15 is not connected to two or more through holes 11. Therefore, each injection hole 15 is provided independently for each through hole 11, and adhesive injected into one injection hole 15 is introduced only into one through hole 11 connected to that injection hole 15.

[0098] The inner diameter of injection hole 15 is large enough to allow liquid adhesive injected from upper surface 10c to be introduced into through holes 11. The size that allows liquid adhesive to be introduced into through holes 11 means a size that allows the liquid adhesive to flow through injection hole 15 and reach through holes 11. The inner diameter of injection hole 15 is set to be smaller than the pitch between through holes 11. The inner diameter of injection hole 15 may be smaller or larger than the inner diameter of through holes 11, as long as the adhesive can be introduced into through holes 11. The inner diameter of injection hole 15 may be the same as the inner diameter of through holes 11.

[0099]

[0033] Even with this configuration, the same effects as those of the above-mentioned embodiment can be achieved. Furthermore, with holding equipment 10E for optical fiber having a plurality of injection holes 15, when fixing the optical fiber 20 in the through hole 11 with adhesive, the adhesive can be injected into the through hole 11 separately from a route separate from the through hole 11. By adjusting the position of the injection hole 15 relative to the through hole 11 and the injection amount of adhesive, etc., taking into account the fluidity of the adhesive, it is possible to reliably fill the gap between the optical fiber 20 and the through hole 11 with adhesive. This allows the adhesive to be distributed evenly around the optical fiber 20, so that the stress generated when the adhesive hardens can be applied uniformly to the optical fiber 20. As a result, it is possible to reduce the possibility of the optical fiber 20 being tilted due to stress being applied in one direction. Therefore, with the above configuration, it is possible to more reliably reduce the possibility of the insertion part 26 of the optical fiber 20 being tilted inside the through hole 11, so it is possible to more reliably prevent the tip surface 20a of the optical fiber 20 from coming into strong contact with the inner surface S33 of the ferrule hole 33 when inserting the optical fiber 20 into the ferrule hole 33. As a result, it is possible to more reliably reduce the possibility of a large load being applied to the optical fiber 20.

[0100] The present disclosure is not limited to the above-mentioned embodiments and modifications, and various other modifications are possible. For example, the above-mentioned embodiments and modifications may be combined with each other within a consistent range according to the required purpose and effect. The configuration of holding equipment for optical fiber is not limited to the above-mentioned embodiments and modifications. For example, when multiple optical fibers arranged in two rows are held in holding equipment for optical fiber, the through holes may also be arranged in two rows corresponding to the arrangement of the multiple optical fibers. The inner diameter of the through hole of holding equipment for optical fiber does not need to be constant at each position along the through hole, and may vary at each position along the through hole. Both the coating removal part and the coating part of the optical fiber may be inserted into the through hole of holding equipment for optical fiber.

[0101] DESCRIPTION OF SYMBOLS 1...Optical coupling structure 2, 2A, 2B, 2C...Optical connector 2a...First optical connector 2b...Second optical connector 10, 10A, 10B, 10C, 10D, 10E, 100, 110...Holding equipment for optical fiber 10a...Front surface (an example of the "first surface" of the present disclosure) 10b...Rear surface (an example of the "second surface" of the present disclosure) 10c...Upper surface 10d...Lower surface 10e, 10f...Side surface 11, 11A, 11B, 111...Through hole 11a, 11b, 31, 50a...Opening 11c...Constant diameter portion 11d...Expanded diameter portion 12, 13, 13A, 13B...Supporting portion 13a, 13b...Fixing hole 13c...Supporting surface 14a...Core 14b...Cladding 14c...Coating 15...Injection hole 20, 120...Optical fiber 20a...tip surface (an example of the "tip" in the present disclosure) 22...coating removal portion 23...coating portion 25, 25A...optical fiber coupling structure 26, 26A...insertion portion 27, 27A...protrusion 30, 30A, 130...ferrule 30a...front surface 30b...rear surface 32, 32A...accommodation hole 32a, 32b, 32c, 32d, 32e, 32g, S33...inner surface 32f...V-groove 33, 133...ferrule hole 34...guide hole 35...window 40...guide pin 50...spacer 60, 160...cured adhesive 120a...tip surface D22, D23, A, E...outer diameter D11, D11A, D33, B, C...inner diameter C11, C20, C33, C111, C133... Central axis L1, L2, L6... Length L3... Distance L4, L5, L7, L8... Displacement amount P11... Contact position θ... Angle

Claims

1. An optical fiber holding component that is placed inside a ferrule having multiple ferrule holes formed therein and holds multiple optical fibers that are inserted into each of the multiple ferrule holes, The first and second faces are aligned in the first direction, A plurality of through holes that penetrate the first surface and the second surface in the first direction and are arranged in a second direction that intersects the first direction, corresponding to the plurality of ferrule holes, Equipped with, Each of the aforementioned plurality of optical fibers is An insertion portion is inserted into and held in each of the multiple through holes, It includes a projection that protrudes outward from the through hole and is inserted into each of the plurality of ferrule holes, The minimum inner diameter of the through hole is greater than or equal to the maximum outer diameter of the insertion portion. When viewed along the first direction, the central axis of the ferrule hole coincides with the central axis of the through hole, and when the central axis of the insertion portion is tilted to its maximum extent with respect to the central axis of the through hole inside the through hole, the tip of the protruding portion is located inside the inner surface of the ferrule hole when viewed along the first direction. Optical fiber holding component.

2. The maximum inner diameter of the through hole is smaller than the maximum inner diameter of the ferrule hole. The optical fiber holding component according to claim 1.

3. The optical fiber is A coating removal portion from which a portion of the coating has been removed from the aforementioned tip, The coating portion includes the coating that remains, The coating removal portion and the coating portion, of which only the coating removal portion is inserted into the through hole as the insertion portion. The optical fiber holding component according to claim 1.

4. The system further comprises a support portion positioned between the through-hole and the second surface in the first direction, and capable of supporting the covering portion positioned outside the through-hole. The optical fiber holding component according to claim 3.

5. The optical fiber is A coating removal portion from which a portion of the coating has been removed from the aforementioned tip, The coating portion includes the coating that remains, Of the coating removal portion and the coating portion, only the coating portion is inserted into the through hole as the insertion portion. The optical fiber holding component according to claim 1.

6. The aforementioned through hole is A fixed-diameter portion having a constant inner diameter in the first direction capable of holding the insertion portion, Including an enlarged diameter portion formed between the constant diameter portion and the second surface in the first direction, the inner diameter of which widens as it moves from the constant diameter portion toward the second surface in the first direction, The optical fiber holding component according to any one of claims 1 to 5.

7. The through hole is configured to rotatably hold the insertion portion around its central axis. The optical fiber holding component according to any one of claims 1 to 5.

8. The optical fiber includes at least one core in a region offset from the central axis of the optical fiber. The optical fiber holding component according to any one of claims 1 to 5.

9. A third surface connects the first surface and the second surface in the first direction, The system further comprises a plurality of injection holes extending from the third surface so as to intersect with the plurality of through holes and communicating individually with each of the plurality of through holes, into which an adhesive for bonding the plurality of optical fibers to the plurality of through holes can be injected. The optical fiber holding component according to any one of claims 1 to 5.

10. An optical fiber holding component according to any one of claims 1 to 5, The plurality of optical fibers, each inserted into the plurality of through holes and fixed to each of the plurality of through holes by a cured adhesive, A fiber optic coupling structure comprising the above.

11. The optical fiber coupling structure according to claim 10, The optical fiber coupling structure comprises the ferrule into which the optical fiber coupling structure is inserted, The protruding portions of the plurality of optical fibers are each inserted into the plurality of ferrule holes. Optical connector.

12. The optical connector according to claim 11 comprises a first optical connector and a second optical connector, The first optical connector and the second optical connector are an optical coupling structure in which they face each other with a gap in between in the first direction.

13. A manufacturing method for producing the optical fiber coupling structure described in claim 10, The process of preparing the optical fiber holding components, including auxiliary optical fiber holding components and fixing optical fiber holding components, The steps include aligning the auxiliary optical fiber holding component with respect to the fixing optical fiber holding component in the first direction, With the auxiliary optical fiber holding component and the fixing optical fiber holding component arranged in the first direction, the optical fiber is inserted in the first direction from the through-hole of the fixing optical fiber holding component to the through-hole of the auxiliary optical fiber holding component. With the insertion portion of the optical fiber inserted into the through-hole of the fixing optical fiber holding component and the protruding portion of the optical fiber inserted into the through-hole of the auxiliary optical fiber holding component, the process of fixing the insertion portion to the fixing optical fiber holding component by injecting adhesive into the through-hole of the fixing optical fiber holding component and curing the adhesive, A method for manufacturing an optical fiber coupling structure, comprising the step of removing the auxiliary optical fiber holding component while the insertion portion is fixed to the fixed optical fiber holding component.

14. In the step of aligning the auxiliary optical fiber holding component with respect to the fixing optical fiber holding component in the first direction, The auxiliary optical fiber holding component is brought into contact with the fixed optical fiber holding component in the first direction such that the through-hole of the auxiliary optical fiber holding component communicates with the through-hole of the fixed optical fiber holding component in the first direction. A method for manufacturing an optical fiber coupling structure according to claim 13.

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