Optical connector, ferrule, and optical coupling structure

Abstract

An optical connector according to one embodiment of the present disclosure is provided with: a plurality of optical fibers each having a coating portion and a coating removal portion, and each having at least one of a core and a stress application portion at a position offset from a central axis; and a ferrule having a front end surface and a rear end surface arranged in a first direction in which the central axis extends, and a plurality of fiber holding portions extending between the front end surface and the rear end surface in the first direction, and a plurality of optical fibers are arranged in a second direction intersecting the first direction and are respectively held. Each of the plurality of optical fiber holding portions includes: a holding hole into which the coating removal portion is inserted in the first direction and which holds the position of the coating removal portion in a plane perpendicular to the first direction; and an introduction part which is located between the holding hole and the rear end surface and has an inner wall surface into which an imaginary circle having a diameter larger than the inner diameter of the holding hole is inscribed. The length of the holding hole in the first direction is shorter than the length of the introduction portion in the first direction.

Description

Technical Field

[0001] The present disclosure relates to an optical connector, a ferrule and an optical coupling structure.

[0002] This application claims the priority based on Japanese application No. 2022-123796 filed on August 3, 2022, and cites all the contents described in the said Japanese application. Background Art

[0003] Patent document 1 discloses a ferrule for an optical connector. A plurality of fiber insertion holes for inserting a plurality of optical fibers are formed inside the ferrule. The plurality of fiber insertion holes each have: a thin-diameter portion opening at the top end surface; and an introduction portion connected to the thin-diameter portion and having an inner diameter larger than the inner diameter of the thin-diameter portion. When the plurality of optical fibers are mounted on the ferrule, each optical fiber is inserted from the introduction portion and fixed to the thin-diameter portion.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2002-333549 Summary of the invention

[0007] An optical connector according to one embodiment of the present disclosure comprises: a plurality of optical fibers, each having a coating removal portion obtained by removing a predetermined length of resin coating from a top end surface and a coating portion in which the resin coating remains, and each having at least one of a core and a stress imparting portion at a position offset from a central axis; and a ferrule having a front end face and a rear end face and a plurality of optical fiber holding portions, wherein the front end face and the rear end face are arranged in a first direction extending from the central axis, and the plurality of optical fiber holding portions extend between the front end face and the rear end face in the first direction, and are arranged in a second direction intersecting the first direction and respectively hold a plurality of optical fibers. The plurality of optical fiber holding portions respectively include: a holding hole into which the coating removal portion is inserted along the first direction, and the coating removal portion is held in a manner that maintains the position of the coating removal portion in a plane perpendicular to the first direction; and an introduction portion located between the holding hole and the rear end face, and having an inner wall surface inscribed by an imaginary circle, wherein the imaginary circle has a diameter larger than the inner diameter of the holding hole. The length of the holding hole in the first direction is shorter than the length of the introduction portion in the first direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a perspective view of the optical connector according to the first embodiment.

[0009] Figure 2 yes Figure 1 A cross-sectional view of an optical connector.

[0010] Figure 3 yes Figure 1 A front view of an optical fiber included in an optical connector.

[0011] Figure 4 yes Figure 1 A cross-sectional view of a ferrule included in an optical connector.

[0012] Figure 5 yes Figure 4 Another cross-sectional view of the ferrule.

[0013] Figure 6 It means to install the optical fiber in Figure 4 A cross-sectional view of the ferrule.

[0014] Figure 7 Yes Figure 1 A three-dimensional diagram of the optical coupling structure of an optical connector.

[0015] Figure 8 This is a diagram for explaining the problem of the optical connector of Comparative Example 1.

[0016] Fig. 9 This is a diagram for explaining the problem of the optical connector of Comparative Example 2.

[0017] Fig.10 It is a cross-sectional view showing a modified example of the ferrule.

[0018] Fig.11 Yes means Fig.10 A cross-sectional view of an optical fiber holding portion of a ferrule.

[0019] Fig.12 Yes means Fig.11 A cross-sectional view of another modified example of the optical fiber holding portion.

[0020] Fig.13 It is a cross-sectional view of the optical connector according to the second embodiment.

[0021] Fig.14 yes Fig.13 A cross-sectional view of a ferrule included in an optical connector.

[0022] Fig.15 yes Fig.13 A perspective view of an optical fiber holding component included in an optical connector.

[0023] Fig.16 The optical fiber holding component is installed on Fig.14 A cross-sectional view of the ferrule.

[0024] Fig.17 Yes means Fig.13 A cross-sectional view of a modified example of an optical connector.

[0025] Fig.18 yes Fig.17 A perspective view of an optical fiber holding component included in an optical connector.

[0026] Fig.19 Yes means Fig.13 A cross-sectional view of another modified example of the optical connector.

[0027] Fig. 20 yes Fig.19 A perspective view of an optical fiber holding component included in an optical connector.

[0028] Fig.21 It is a cross-sectional view showing a modified example of the optical fiber holding member. DETAILED DESCRIPTION

[0029] [Problems to be Solved by the Present Disclosure]

[0030] Sometimes, a plurality of optical fibers that need to be rotated and aligned are installed in the ferrule described in Patent Document 1. However, the gap between the thin-diameter portion of the optical fiber insertion hole of the ferrule and the optical fiber is very small, so when the optical fiber is inserted into the thin-diameter portion, the optical fiber is easily twisted and rotated due to the friction between the thin-diameter portion and the optical fiber. Such twisting and rotating may become the main cause of the angular deviation of the rotation direction of the optical fiber. Therefore, it is difficult to accurately hold such an optical fiber in such a ferrule.

[0031] [Effects of the present disclosure]

[0032] According to the optical connector, ferrule, and optical coupling structure disclosed herein, a plurality of optical fibers can be held with high accuracy.

[0033] [Description of Embodiments of the Present Disclosure]

[0034] First, the contents of the embodiments of the present disclosure will be listed and described.

[0035] (1) An optical connector according to one embodiment of the present disclosure comprises: a plurality of optical fibers, each having a coating removal portion obtained by removing a predetermined length of resin coating from a top end surface and a coating portion in which the resin coating remains, and each having at least one of a core and a stress imparting portion at a position offset from a central axis; and a ferrule having a front end face and a rear end face and a plurality of optical fiber holding portions, wherein the front end face and the rear end face are arranged in a first direction in which the central axis extends, and the plurality of optical fiber holding portions extend between the front end face and the rear end face in the first direction and are arranged in a second direction intersecting the first direction and respectively hold the plurality of optical fibers. The plurality of optical fiber holding portions respectively include: a holding hole into which the coating removal portion is inserted along the first direction and holds the coating removal portion in a manner that maintains the coating removal portion in a position in a plane perpendicular to the first direction; and an introduction portion located between the holding hole and the rear end face and having an inner wall surface inscribed by an imaginary circle, wherein the imaginary circle has a diameter larger than the inner diameter of the holding hole. The length of the holding hole in the first direction is shorter than the length of the introduction portion in the first direction.

[0036] In the above optical connector, when a plurality of optical fibers are installed in the ferrule, the optical fibers that have been rotated and aligned are inserted into the holding hole from the introduction part of the optical fiber holding part along the first direction. In the holding hole, the coating removal part is held at a position in a plane perpendicular to the first direction, so the gap between the holding hole and the coating removal part is set small. Therefore, when the optical fiber is inserted into the holding hole, friction is easily generated between the holding hole and the coating removal part. On the other hand, the introduction part has an inner wall surface for inscribing an imaginary circle, wherein the imaginary circle has a diameter larger than the inner diameter of the holding hole, so when the optical fiber is inserted into the holding hole, it is relatively difficult to generate friction between the introduction part and the coating removal part. Therefore, in the above optical connector, the length of the holding hole in the first direction is set shorter than the length of the introduction part in the first direction. If the length of the holding hole is shortened in this way, the possibility of friction between the holding hole and the coating removal part can be reduced. Moreover, even if friction occurs between the holding hole and the coating removal part, the friction resistance between the holding hole and the coating removal part can be reduced. As a result, the torsional rotation of the optical fiber caused by the friction between the holding hole and the coating removal portion can be suppressed. Thus, the angular deviation (rotational deviation) of the position of the optical fiber in the rotation direction can be suppressed. Therefore, according to the above optical connector, a plurality of optical fibers can be held with good accuracy.

[0037] (2) In the optical connector described in (1) above, the introduction portion may be an introduction hole connected to the retaining hole in the first direction. The inner diameter of the introduction hole defined by the diameter of the imaginary circle may be greater than or equal to the outer diameter of the coating portion. The coating portion may be inserted into the introduction hole. In this case, by inserting the coating portion into the introduction hole, the posture of the optical fiber can be restricted to a state along the first direction. Thus, the coating removal portion can be inserted into the retaining hole along the first direction without causing friction between the coating removal portion and the retaining hole. As a result, the occurrence of rotational deviation of the optical fiber can be more reliably suppressed. Furthermore, if such a structure in which the introduction portion has a hole shape is adopted, the coating removal portion can be easily introduced from the introduction hole to the retaining hole.

[0038] (3) In the optical connector described in (1) above, the introduction portion may be an introduction hole connected to the retaining hole in the first direction. The inner diameter of the introduction hole defined by the diameter of the imaginary circle may be greater than or equal to the outer diameter of the coating removal portion. Only the coating removal portion of the coating removal portion and the coating portion may be inserted into the introduction hole. In this case, by inserting the coating removal portion into the introduction hole, the posture of the optical fiber can be restricted to a state along the first direction. Thus, the coating removal portion can be inserted into the retaining hole along the first direction without causing friction between the coating removal portion and the retaining hole. As a result, the occurrence of rotational deviation of the optical fiber can be more reliably suppressed. Furthermore, if such a structure in which the introduction portion has a hole shape is adopted, the coating removal portion can be easily introduced from the introduction hole to the retaining hole.

[0039] (4) In the optical connector described in (1) above, the introduction portion may be an introduction groove connected to the retaining hole in the first direction. The diameter of an imaginary circle inscribed in the introduction groove may be greater than or equal to the outer diameter of the coating removal portion. Only the coating removal portion of the coating removal portion and the coating portion may be accommodated in the introduction groove. In this case, by accommodating the coating removal portion in the introduction groove, the posture of the optical fiber can be restricted to a state along the first direction. Thus, the coating removal portion can be inserted into the retaining hole along the first direction in a state where friction between the coating removal portion and the retaining hole is not easily generated. As a result, the occurrence of rotational deviation of the optical fiber can be more reliably suppressed. Moreover, if such a configuration in which the introduction portion has a groove shape is adopted, the position of the optical fiber relative to the introduction portion can be positioned with good accuracy.

[0040] (5) In the optical connector described in (1) above, the introduction portion may be an introduction groove connected to the retaining hole in the first direction. The diameter of an imaginary circle inscribed in the introduction groove may be greater than or equal to the outer diameter of the coating portion. The coating portion may be accommodated in the introduction groove. In this case, by accommodating the coating portion in the introduction groove, the posture of the optical fiber can be restricted to a state along the first direction. Thus, the coating removal portion can be inserted into the retaining hole along the first direction without causing friction between the coating removal portion and the retaining hole. As a result, the occurrence of rotational deviation of the optical fiber can be more reliably suppressed. Moreover, if such a configuration in which the introduction portion has a groove shape is adopted, the position of the optical fiber relative to the introduction portion can be positioned with good accuracy.

[0041] (6) The optical connector described in any one of (1) to (5) above may further include: a fiber holding component that is arranged inside the ferrule at a position opposite to the plurality of fiber holding portions in the first direction and holds the plurality of optical fibers. In this case, the fiber holding component is arranged inside the ferrule while the plurality of optical fibers that have been rotationally aligned are held in the fiber holding component, so that the coating removal portions of the plurality of optical fibers that have been rotationally aligned can be inserted into the plurality of holding holes together. This facilitates the installation of the plurality of optical fibers relative to the ferrule.

[0042] (7) In the optical connector described in (6) above, the optical fiber holding member may be a resin layer that covers the coatings of the plurality of optical fibers collectively. In this case, the optical fiber holding member can be realized with a simple structure.

[0043] (8) In the optical connector described in (6) above, the optical fiber holding component may have a plurality of V-grooves extending in the first direction and arranged in the second direction to accommodate the plurality of optical fibers, respectively. In this case, the optical fiber holding component is arranged inside the ferrule while the plurality of optical fibers that have been rotated and aligned are accommodated and fixed in the plurality of V-grooves of the optical fiber holding component, thereby allowing the coating removal portions of the plurality of optical fibers to be inserted into the plurality of holding holes together while the plurality of optical fibers are positioned along the first direction. This can more reliably reduce the possibility of friction between the holding holes and the coating removal portions, and facilitate the installation of the plurality of optical fibers relative to the ferrule.

[0044] (9) In the optical connector described in (6) above, the optical fiber holding component may have a plurality of through holes that penetrate in a first direction and are arranged in a second direction and allow a plurality of optical fibers to be inserted therethrough. In this case, the optical fiber holding component is arranged inside the ferrule while the plurality of optical fibers that have been rotationally aligned are inserted and fixed to the plurality of through holes of the optical fiber holding component. This allows the coating removal portions of the plurality of optical fibers to be inserted into the plurality of holding holes together while the plurality of optical fibers are oriented along the first direction. This makes it possible to more reliably reduce the possibility of friction between the holding holes and the coating removal portions, and facilitate the installation of the plurality of optical fibers relative to the ferrule.

[0045] (10) In the optical connector described in any one of (1) to (9) above, the optical fiber may be any one of a multi-core optical fiber, a polarization-maintaining optical fiber, and a bundled optical fiber. When such an optical fiber is used, it is necessary to perform rotational alignment of the optical fiber, and thus rotational deviation of the optical fiber due to friction between the retaining hole and the coating removal portion may become a problem. In contrast, in the optical connector described above, the occurrence of rotational deviation of the optical fiber can be suppressed, and thus the above-mentioned effect can be appropriately obtained.

[0046] (11) A ferrule according to one embodiment of the present disclosure is a ferrule for holding a plurality of optical fibers, wherein the plurality of optical fibers each have a coating removal portion obtained by removing a predetermined length of resin coating from a top end surface and a coating portion in which the resin coating remains, and each have at least one of a core and a stress applying portion at a position offset from a central axis. The ferrule comprises: a front end face; a rear end face arranged in a first direction with the front end face; and a plurality of optical fiber holding portions, which are configured to extend between the front end face and the rear end face in the first direction and are arranged in a second direction intersecting the first direction and respectively hold the plurality of optical fibers. The plurality of optical fiber holding portions each include: a holding hole into which the coating removal portion is inserted along the first direction and which is configured to maintain the position of the coating removal portion in a plane perpendicular to the first direction; and an introduction portion, which is located between the holding hole and the rear end face and has an inner wall surface inscribed in an imaginary circle, wherein the imaginary circle has a diameter larger than the inner diameter of the holding hole. The length of the holding hole in the first direction is shorter than the length of the introduction portion in the first direction. In the ferrule, by shortening the length of the holding hole as described above, the occurrence of rotational deviation of the optical fiber can be suppressed. Therefore, according to the above-mentioned ferrule, a plurality of optical fibers can be held with high accuracy.

[0047] (12) An optical coupling structure according to one embodiment of the present disclosure includes a first optical connector and a second optical connector as the optical connectors described in any one of (1) to (10) above. The first optical connector is arranged to be opposite to the second optical connector in a first direction and optically coupled to the second optical connector. The optical coupling structure includes the first optical connector and the second optical connector as the optical connectors described above, and thus, as described above, can hold a plurality of optical fibers with good accuracy.

[0048] [Details of the embodiments of the present disclosure]

[0049] Hereinafter, specific examples of optical connectors, ferrules, and optical coupling structures of the embodiments of the present disclosure are described with reference to the accompanying drawings. The present disclosure is not limited to these examples, but is shown by the claims, and is intended to include all changes within the meaning and scope equivalent to the claims. In the following description, the same elements are marked with the same reference numerals in the description of the drawings, and repeated descriptions are appropriately omitted.

[0050] [First embodiment]

[0051] Figure 1 It is a perspective view of the optical connector 1 according to the first embodiment. Figure 2 This is a cross-sectional view of the optical connector 1. In the following description, for the sake of convenience, the long dimension of the optical connector 1 is set to the X direction (an example of the "first direction"), the short dimension of the optical connector 1 is set to the Y direction (an example of the "second direction"), and the height direction of the optical connector 1 is set to the Z direction. The X direction, the Y direction, and the Z direction intersect with each other (in one example, they are orthogonal). In the following description, one side of the Z direction is sometimes referred to as "upper", the other side of the Z direction is sometimes referred to as "lower", one side of the X direction is sometimes referred to as "front", and the other side of the X direction is sometimes referred to as "rear".

[0052] like Figure 1 As shown, the optical connector 1 includes, for example, a plurality of optical fibers 10 and a ferrule 20 for holding the plurality of optical fibers 10. The plurality of optical fibers 10 are cables for transmitting optical signals. The plurality of optical fibers 10 extend in the X direction and are arranged in a row in the Y direction. Figure 1 2 shows an example in which twelve optical fibers 10 are arranged in a row in the Y direction. However, the number of the plurality of optical fibers 10 is not limited to twelve, and may be four, eight, twenty-four, or other numbers. The plurality of optical fibers 10 may also be arranged in two or more rows.

[0053] like Figure 2 As shown, each optical fiber 10 has, for example, a tip surface 11, a coating removal portion 12, and a coating portion 13. Figure 2Hereinafter, the optical fiber 10 may be shown in light gray for ease of understanding. The tip surface 11 is the end surface of the tip of the optical fiber 10 located in the X direction. The coating removal portion 12 is a portion of the optical fiber 10 where the resin coating 15 is removed by a predetermined length from the tip surface 11 (see FIG. 1 ). Figure 3 ). The coating portion 13 is a portion of the optical fiber 10 where the resin coating 15 remains. The coating portion 13 is provided on the side opposite to the top end face 11 across the coating removal portion 12. In the coating removal portion 12, the cladding 16 (see Figure 3 ) is exposed. The outer diameter of the coating removal portion 12 (i.e., the diameter of the cladding 16) is, for example, greater than 30 μm and less than 300 μm. In the coating portion 13, the cladding 16 of the optical fiber 10 is covered with the resin coating 15. The outer diameter of the coating portion 13 is, for example, greater than 50 μm and less than 500 μm.

[0054] Figure 3 1 is a front view of the optical fiber 10. The optical fiber 10 is an optical fiber that needs to be rotated relative to the central axis L. In this embodiment, a multi-core optical fiber (MCF: Multi Core Fiber) is given as an example of the optical fiber 10 that needs to be rotated. In this case, the optical fiber 10 has a plurality of cores 17 covered by a cladding 16. Figure 3 In the example shown, the plurality of cores 17 include a central core 17a disposed on the central axis L, and a plurality of (e.g., six) peripheral cores 17b disposed at positions offset from the central axis L. The state in which the peripheral cores 17b are offset from the central axis L can be set to a state in which the centers of the peripheral cores 17b do not coincide with the central axis L when viewed in the X direction.

[0055] The number and configuration of the plurality of fiber cores 17 are not limited to Figure 3 The examples shown can be changed appropriately. For example, the number of the multiple cores 17 is not limited to six, and can be two, four, or eight or more. The multiple cores 17 may not have a central core 17a arranged on the central axis L. As the optical fiber 10 that needs to be rotationally adjusted, in addition to multi-core optical fibers, for example, bundle optical fibers and polarization maintaining fibers (PMF: Polarization Maintaining Fiber) are also mentioned. In the case where the optical fiber 10 is a polarization maintaining fiber, the optical fiber 10 has a stress-applying portion at a position deviated from the central axis L. In this case, for example, the optical fiber 10 has a central core arranged on the central axis L, and a pair of stress-applying portions are arranged on both sides of the central core.

[0056] Figure 4 is a cross-sectional view of the ferrule 20 . Figure 5 1 is another cross-sectional view showing the ferrule 20 . Figure 4 and Figure 5 Shows from Figure 2The optical connector 1 is in a state where the plurality of optical fibers 10 are removed. The ferrule 20 is a component that holds the ends of the plurality of optical fibers 10, and is, for example, an MT (Mechanical Transfer) ferrule. The ferrule 20 has a substantially rectangular shape. The ferrule 20 is made of, for example, a resin such as PPS (Polyphenylene Sulfide). The ferrule 20 has, for example, a front end face 21, a rear end face 22, a pair of guide holes 23, 23 (see Figure 1 ), an optical fiber accommodating portion 24 and a plurality of optical fiber retaining portions 25.

[0057] The front end face 21 is an end face of the front end of the ferrule 20 located in the X direction. The rear end face 22 is an end face of the rear end of the ferrule 20 located in the X direction. The front end face 21 and the rear end face 22 extend in the Y direction and the Z direction and are arranged in the X direction. A pair of guide holes 23, 23 are opened at both ends of the front end face 21 in the Y direction and extend from the front end face 21 to the rear end face 22 in the X direction (refer to Figure 1 The rear end face 22 is formed with an opening 22a capable of receiving a plurality of optical fibers 10 at a time.

[0058] The optical fiber accommodating portion 24 is formed at the rear portion of the ferrule 20 between the front end face 21 and the rear end face 22 and close to the rear end face 22. The rear portion of the ferrule 20 is the portion of the ferrule 20 from the wall surface 26 formed inside the ferrule 20 to the rear end face 22. The wall surface 26 is a plane along the Y direction and the Z direction, and is arranged between the front end face 21 and the rear end face 22 in the X direction. The optical fiber accommodating portion 24 is an internal space formed between the wall surface 26 and the rear end face 22 inside the rear portion of the ferrule 20. The optical fiber accommodating portion 24 extends forward from the opening 22a of the rear end face 22 and is connected to a plurality of optical fiber holding portions 25. The optical fiber accommodating portion 24 can accommodate a plurality of optical fibers 10 received from the opening 22a at once.

[0059] A plurality of optical fiber holding portions 25 are formed at the front portion of the ferrule 20 near the front end face 21 between the front end face 21 and the rear end face 22. The front portion of the ferrule 20 is a portion of the ferrule 20 from the front end face 21 to the wall surface 26. The plurality of optical fiber holding portions 25 extend in the X direction in the front portion of the ferrule 20 corresponding to the plurality of optical fibers 10 and are arranged in the Y direction. The plurality of optical fiber holding portions 25 respectively hold the plurality of optical fibers 10 introduced into the optical fiber accommodating portion 24.

[0060] Each optical fiber holding portion 25 has, for example, a holding hole 27 for holding the optical fiber 10 and an introduction hole 28 (an example of an “introduction portion”) for introducing the optical fiber 10 into the holding portion. The holding hole 27 is a circular, thin-diameter hole extending from the front end face 21 in the X direction. The inner wall surface S1 constituting the holding hole 27 has a constant inner diameter D1 at each position along the X direction. Figure 2As shown in FIG. 2 , the coating removed portion 12 of the optical fiber 10 is inserted into the holding hole 27. The holding hole 27 is opened on the front end face 21, and the top end face 11 of the optical fiber 10 is exposed from the opening of the front end face 21. The holding hole 27 maintains the position of the coating removed portion 12 on the YZ plane perpendicular to the X direction. Therefore, in order to determine the position of the coating removed portion 12 relative to the holding hole 27 on the YZ plane, the gap between the holding hole 27 and the coating removed portion 12 on the YZ plane is set to be extremely small.

[0061] like Figure 4 and Figure 5 As shown, the introduction hole 28 is a circular large-diameter hole extending from the holding hole 27 to the wall surface 26 in the X direction. The introduction hole 28 is connected to the holding hole 27 in the X direction and is formed to be larger than the holding hole 27 when viewed in the X direction. The introduction hole 28 is connected to the holding hole 27 in the X direction, which means that the internal space of the introduction hole 28 is connected to the internal space of the holding hole 27 in the X direction. When viewed in the X direction, the center of the introduction hole 28 is, for example, consistent with the center of the holding hole 27. The center of the introduction hole 28 may not be strictly consistent with the center of the holding hole 27. The deviation between the center of the introduction hole 28 and the center of the holding hole 27 observed in the X direction may be, for example, 3 μm or less. The introduction hole 28 opens on the wall surface 26 and receives the optical fiber 10 from the opening of the wall surface 26. The introduction hole 28 includes, for example, a tapered portion 28a and a sizing portion 28b.

[0062] The calibrating portion 28b is a portion of the introduction hole 28 in the X direction that is close to the rear end surface 22. The calibrating portion 28b extends from the rear end surface 22 toward the front in the X direction. The inner wall surface S2 constituting the calibrating portion 28b has a constant inner diameter D2 at each position along the X direction. The inner diameter D2 of the inner wall surface S2 is larger than the inner diameter D1 of the inner wall surface S1. Figure 3 As shown, the inner diameter D2 of the inner wall surface S2 can be expressed as the diameter D2 of the imaginary circle C2 inscribed in the inner wall surface S2. The inner diameter D2 of the inner wall surface S2 is set to be, for example, the same as the outer diameter d2 of the coating portion 13, or slightly larger than the outer diameter d2 of the coating portion 13. On the other hand, the inner diameter D1 of the inner wall surface S1 is set to be, for example, the same as the outer diameter d1 of the coating removal portion 12 of the optical fiber 10, or slightly larger than the outer diameter d1 of the coating removal portion 12. Figure 2 As shown, the coating 13 is inserted into the sizing portion 28b. By inserting the coating 13 into the sizing portion 28b, the movement of the optical fiber 10 in the YZ plane is restricted, and the posture of the optical fiber 10 is restricted to a state along the X direction.

[0063] like Figure 4 and Figure 5As shown in the figure, the tapered portion 28a is provided between the sizing portion 28b and the holding hole 27. The tapered portion 28a is formed so that the inner diameter of the tapered portion 28a decreases as it moves from the sizing portion 28b toward the holding hole 27 in the X direction. The coating removal portion 12 of the optical fiber 10 inserted into the sizing portion 28b is guided to the holding hole 27 through the tapered portion 28a. In this way, the introduction hole 28 has a function of assisting the introduction of the coating removal portion 12 into the holding hole 27.

[0064] In the present embodiment, the length L1 of the holding hole 27 in the X direction is set shorter than the length L2 of the introduction hole 28 in the X direction. The length L1 of the holding hole 27 is the distance in the X direction from the front end face 21 to the connection portion P1 of the holding hole 27 and the introduction hole 28. The length L2 of the introduction hole 28 is the distance in the X direction from the connection portion P1 to the wall surface 26. The total length (L1+L2) of the length L1 of the holding hole 27 and the length L2 of the introduction hole 28 is equivalent to the length in the X direction of the optical fiber holding part 25, that is, the distance in the X direction from the front end face 21 to the rear end face 22. Therefore, the length L1 of the holding hole 27 is shorter than the length L2 of the introduction hole 28, which can be said to be smaller than half of the length (L1+L2) of the optical fiber holding part 25. For example, when the length of the optical fiber holding part 25 is 4 mm, the length L1 of the holding hole 27 is set to be greater than 0.5 mm and shorter than 2 mm. In one example, the length L2 of the introduction hole 28 is set to 3 mm, and the length L1 of the holding hole 27 is set to 1 mm. When the ratio of the length L2 of the introduction hole 28 to the length (L1+L2) of the optical fiber holding portion 25 is defined, the ratio can be set to, for example, 12% or more and less than 50%.

[0065] Figure 6 A cross-sectional view showing a state where the optical fiber 10 is mounted on the ferrule 20. When mounting the optical fiber 10 on the ferrule 20, for example, the optical fiber 10 that has been rotationally aligned is introduced into the optical fiber housing 24 from the opening 22a of the rear end face 22, and the optical fiber 10 is inserted from the optical fiber housing 24 to the introduction hole 28 of the optical fiber holding portion 25 along the X direction. Here, the length L12 of the coating removal portion 12 is usually set to be half of the length (L1+L2) of the optical fiber holding portion 25, that is, about 2 mm. Therefore, the length L1 of the holding hole 27 is shorter than the length L12 of the coating removal portion 12, and the length L2 of the introduction hole 28 is longer than the length L12 of the coating removal portion 12. In this way, before the top end face 11 of the optical fiber 10 that has entered the introduction hole 28 reaches the holding hole 27, the coating portion 13 enters the introduction hole 28.

[0066] When the coating portion 13 is inserted into the introduction hole 28 along the X direction, the movement of the coating portion 13 on the YZ plane in the introduction hole 28 is restricted, thereby restricting the posture of the optical fiber 10 to a state along the X direction. In this state, the coating removal portion 12 is inserted into the holding hole 27 along the X direction. Thereafter, the optical fiber 10 is fixed to the optical fiber holding portion 25 by an adhesive. Thus, Figure 2 The optical connector 1 shown in the figure. The optical fiber 10 may be rotationally aligned after the coat removal portion 12 is inserted into the holding hole 27. However, in this case, since the gap between the coat removal portion 12 and the holding hole 27 is extremely small, the rotational alignment of the optical fiber 10 may become difficult.

[0067] Figure 7 : is a perspective view of an optical coupling structure 100 of the present embodiment. The optical coupling structure 100 includes, for example, a first optical connector 1a, a second optical connector 1b, a pair of guide pins 40, 40, and a spacer 50. The first optical connector 1a and the second optical connector 1b have the same structure as the optical connector 1 described above. In the optical coupling structure 100, the front end surface 21 of the first optical connector 1a and the front end surface 21 of the second optical connector 1b are opposed to each other in the X direction with a gap therebetween. The pair of guide pins 40, 40 are fitted into a pair of guide holes 23, 23 of the first optical connector 1a and a pair of guide holes 23, 23 of the second optical connector 1b. Thus, the positions of the first optical connector 1a and the second optical connector 1b in the YZ plane are defined.

[0068] The spacer 50 is a plate-shaped member having an opening 50a. The spacer 50 is arranged between the front end face 21 of the first optical connector 1a and the front end face 21 of the second optical connector 1b. The opening 50a allows a plurality of optical paths extending between the first optical connector 1a and the second optical connector 1b to pass through. Thus, the first optical connector 1a and the second optical connector 1b are optically coupled. The spacer 50 abuts against the front end face 21 of the first optical connector 1a and the front end face 21 of the second optical connector 1b. Thus, the interval between the first optical connector 1a and the second optical connector 1b in the X direction is specified.

[0069] The effects obtained by the optical connector 1 , the ferrule 20 , and the optical coupling structure 100 of the present embodiment described above will be described together with the problems of the comparative example.

[0070] Figure 81 is a diagram for explaining the problem of the optical connector 200 of Comparative Example 1. In the optical connector 200 of Comparative Example 1, the length L1a of the holding hole 127 of the optical fiber holding portion 125 formed in the ferrule 120 is set to be the same as the length L2a of the introduction hole 128 of the optical fiber holding portion 125. When the optical fiber 10 is mounted on such a ferrule 120, the coat removal portion 12 of the optical fiber 10 reaches the holding hole 127 before the coating portion 13 of the optical fiber 10 enters the introduction hole 128. In this case, the coat removal portion 12 enters the holding hole 127 in a state where the posture of the optical fiber 10 is greatly tilted from the X direction. When the coat removal portion 12 enters the holding hole 127 at an angle relative to the holding hole 127, the coat removal portion 12 contacts the holding hole 127, and the optical fiber 10 is twisted and rotated due to the friction between the coat removal portion 12 and the holding hole 127. As a result, an angular deviation (i.e., rotational deviation) in the rotational direction of the optical fiber 10 occurs. Furthermore, since the gap between the holding hole 127 and the coat removal portion 12 is set to be extremely small, the coat removal portion 12 is likely to contact the holding hole 127. Therefore, the optical fiber 10 is likely to be rotated and shifted during the process of inserting the coat removal portion 12 into the holding hole 127. Such rotational shift may cause the position of the core on the top surface 11 of the optical fiber 10 to shift, which may cause the degradation of optical characteristics such as an increase in connection loss.

[0071] Fig. 9 1 is a diagram for explaining the problem of the optical connector 300 of Comparative Example 2. In the optical connector 300 of Comparative Example 2, the length L1b of the holding hole 227 of the optical fiber holding portion 225 formed in the ferrule 220 is set to be longer than the length L2b of the introduction hole 228 of the optical fiber holding portion 225. When the optical fiber 10 is mounted on such a ferrule 220, the coat removal portion 12 enters the holding hole 227 in a state where the posture of the optical fiber 10 is further tilted from the X direction. In such a case, the coat removal portion 12 is more likely to contact the holding hole 227, and the rotational deviation of the optical fiber 10 is likely to occur. Moreover, when the holding hole 227 is set to be long, the coat removal portion 12 is more likely to contact the holding hole 227, and the contact area between the coat removal portion 12 and the holding hole 227 becomes larger. In this case, the frictional resistance between the holding hole 227 and the coat removal portion 12 becomes larger, so the rotational deviation of the optical fiber 10 is more likely to occur. As a result, similarly to the optical connector 200 of Comparative Example 1, the positional deviation of the core on the distal end surface 11 of the optical fiber 10 may occur, and degradation of optical characteristics such as increase in connection loss may occur.

[0072] On the other hand, in this embodiment, if Figure 6As shown, the length L1 of the holding hole 27 of the optical fiber holding portion 25 is set shorter than the length L2 of the introduction hole 28. If the length L1 of the holding hole 27 is shortened in this way, the posture of the optical fiber 10 in the introduction hole 28 can be restricted to a state along the X direction. As a result, the optical fiber 10 is centered through the introduction hole 28 so that the center of the optical fiber 10 coincides with the center of the introduction hole 28 when viewed in the X direction. If the optical fiber 10 is centered in advance in this way, the center of the holding hole 27 of the optical fiber 10 can also coincide with the center of the holding hole 27 when viewed in the X direction. As a result, the coat removal portion 12 of the optical fiber 10 can be inserted straightly into the holding hole 27. If the coat removal portion 12 can be inserted straight into the holding hole 27, the coat removal portion 12 is less likely to contact the holding hole 27. As a result, the possibility of friction between the coat removal portion 12 and the holding hole 27 can be reduced. Furthermore, if the length L1 of the holding hole 27 is shorter than the length L2 of the introduction hole 28, even if friction occurs between the holding hole 27 and the coating removal portion 12, the friction resistance between the holding hole 27 and the coating removal portion 12 can be reduced. As a result, the occurrence of torsional rotation of the optical fiber 10 due to the friction between the holding hole 27 and the coating removal portion 12 can be suppressed. Thus, the occurrence of rotational deviation of the optical fiber 10 can be suppressed. Therefore, according to this embodiment, a plurality of optical fibers 10 can be held with good accuracy. Thus, the occurrence of positional deviation of the core 17 on the top surface 11 of the optical fiber 10 can be suppressed. As a result, the occurrence of degradation of optical characteristics such as increase in connection loss can be suppressed.

[0073] As in the present embodiment, the inner diameter D2 of the introduction hole 28 may be larger than the outer diameter d2 of the coating portion 13, and the coating portion 13 may be inserted into the introduction hole 28. In this case, by inserting the coating portion 13 into the introduction hole 28, the posture of the optical fiber 10 can be restricted to a state along the X direction. Thus, the coating removal portion 12 can be inserted into the holding hole 27 along the X direction in a state where friction between the coating removal portion 12 and the holding hole 27 is not likely to occur. As a result, the occurrence of rotational deviation of the optical fiber 10 can be more reliably suppressed. In addition, if the introduction hole 28 having a hole shape is used, the coating removal portion 12 can be easily introduced from the introduction hole 28 to the holding hole 27.

[0074] As in the present embodiment, the optical fiber 10 may be any one of a multi-core optical fiber, a polarization-maintaining optical fiber, and a bundled optical fiber. When such an optical fiber 10 is used, it is necessary to perform rotational alignment of the optical fiber 10, and thus rotational deviation of the optical fiber 10 due to friction between the holding hole 27 and the coating removal portion 12 may become a problem. In contrast, in the present embodiment, the occurrence of rotational deviation of the optical fiber 10 can be suppressed, and thus the above-mentioned effect can be appropriately obtained.

[0075] Fig.10It is a cross-sectional view of a ferrule 20A according to a modified example. Fig.11 FIG. 2 is a cross-sectional view of the optical fiber holding portion 25A provided in the ferrule 20A. Fig.10 As shown in FIG. 2 , the ferrule 20A includes a fiber holding portion 25A instead of the fiber holding portion 25. The fiber holding portion 25A includes an introduction groove 28A (an example of an “introduction portion”) instead of the introduction hole 28. The introduction groove 28A is, for example, a V-groove extending in the X direction and communicates with the holding hole 27 in the X direction. Fig.11 As shown, the inner wall surface of the introduction groove 28A is configured to include a pair of inner side surfaces S2A, S2A. When viewed in the X direction, the diameter D2 of the imaginary circle C2 inscribed in the pair of inner side surfaces S2A, S2A is larger than the diameter D1 of the imaginary circle C1 representing the inner wall surface S1 of the retaining hole 27 (that is, the inner diameter D1 of the retaining hole 27). When viewed in the X direction, the center of the imaginary circle C2, for example, coincides with the center of the retaining hole 27. The diameter D2 of the imaginary circle C2 is, for example, set to coincide with the outer diameter d2 of the covering portion 13 (refer to Figure 2 In this case, the imaginary circle C2 coincides with the outer edge of the covering portion 13.

[0076] The covering portion 13 is accommodated in the introduction groove 28A. By placing the covering portion 13 in the introduction groove 28A, the position of the covering portion 13 in the YZ plane relative to the introduction groove 28A is regulated, and the posture of the optical fiber 10 is restricted to a state along the X direction. The introduction groove 28A assists the introduction of the covering removal portion 12 into the retaining hole 27 by restricting the position and posture of the optical fiber 10 in this way. Even with such a form, the same effect as the optical connector 1 of the first embodiment can be obtained. Moreover, if a structure in which the covering portion 13 is accommodated in the introduction groove 28A is adopted, the position of the optical fiber 10 relative to the introduction groove 28A can be positioned with good precision. The covering portion 13 being accommodated in the introduction groove 28A means that at least a portion of the covering portion 13 is arranged in the internal space of the introduction groove 28A.

[0077] Fig.12 2 is a cross-sectional view of another modified example of an optical fiber holding portion 25B. The optical fiber holding portion 25B has an introduction groove 28B (an example of an "introduction portion") for accommodating the coating removal portion 12. In this case, the diameter D3 of the imaginary circle C3 of the pair of inner side surfaces S2B, S2B inscribed in the introduction groove 28B is larger than the diameter D1 of the imaginary circle C1 (i.e., the inner diameter D1 of the holding hole 27) and smaller than the diameter D2 of the imaginary circle C2. The diameter D2 of the imaginary circle C2 is consistent with the outer diameter d2 of the coating portion 13.

[0078] By accommodating the cover removal portion 12 in the introduction groove 28B, the position of the cover removal portion 12 in the YZ plane relative to the introduction groove 28B is specified, and the posture of the optical fiber 10 is restricted to a state along the X direction. The introduction groove 28B assists the introduction of the cover removal portion 12 into the retaining hole 27 by restricting the position and posture of the optical fiber 10 in this way. Even with such a form, the same effect as the optical connector 1 of the first embodiment can be obtained. Moreover, if a structure is adopted in which the cover removal portion 12 is accommodated in the introduction groove 28B, the position of the optical fiber 10 relative to the introduction groove 28B can be positioned with good precision. The cover removal portion 12 being accommodated in the introduction groove 28B means that at least a portion of the cover removal portion 12 is arranged in the internal space of the introduction groove 28B.

[0079] [Second embodiment]

[0080] Next, an optical connector 1A according to a second embodiment will be described. In the following description of the second embodiment, description of portions overlapping with the first embodiment will be appropriately omitted, and portions different from the first embodiment will be mainly described.

[0081] Fig.13 It is a cross-sectional view of an optical connector 1A according to the second embodiment. Fig.14 It is a cross-sectional view of the ferrule 20B provided in the optical connector 1A. In the optical connector 1A, of the coating removal portion 12 and the coating portion 13, only the coating removal portion 12 is inserted into the introduction hole 28C (an example of an "introduction portion") of the optical fiber holding portion 25C of the ferrule 20B. The coating portion 13 is not inserted into the introduction hole 28C, but is arranged behind the introduction hole 28C (i.e., outside the optical fiber holding portion 25C). The introduction hole 28C includes a tapered portion 28c and a sizing portion 28d instead of the tapered portion 28a and the sizing portion 28b. The inner diameter D4 of the sizing portion 28d is larger than the inner diameter D1 of the holding hole 27. The inner diameter D4 of the sizing portion 28d is larger than the outer diameter d1 of the coating removal portion 12, and smaller than the outer diameter d2 of the coating portion 13. The gap between the introduction hole 28C and the coating removal portion 12 observed in the X direction is set to, for example, 3 μm or more. As shown in FIG. Fig.14 As shown, the length L2 of the introduction hole 28C in the X direction is longer than the length L1 of the holding hole 27 in the X direction. The relationship between the length L2 of the introduction hole 28C and the length L1 of the holding hole 27 may be the same as the relationship between the length L2 of the introduction hole 28 and the length L1 of the holding hole 27 described in the first embodiment.

[0082] The optical fiber housing portion 24 of the ferrule 20B is provided with an optical fiber support portion 29. The optical fiber support portion 29 extends rearward from a position below the optical fiber holding portion 25C on the wall surface 26 of the ferrule 20B. The upper surface of the optical fiber support portion 29 functions as a support surface 29a for supporting the optical fiber holding member 30. The support surface 29a is, for example, a plane extending in the X direction and the Y direction, and is formed perpendicular to the wall surface 26.

[0083] Fig.15 30 is a perspective view of the optical fiber holding component 30. The optical fiber holding component 30 is a component that holds a plurality of optical fibers 10. The optical fiber holding component 30 is formed as a separate body from the ferrule 20B and is arranged inside the ferrule 20B. The optical fiber holding component 30 is made of a material such as resin or metal. The optical fiber holding component 30 includes, for example, a front surface 30a, a rear surface 30b, an upper surface 30c, a lower surface 30d, a side surface 30e, and a side surface 30f.

[0084] The front surface 30a is an end surface at the front end of the optical fiber holding component 30 located in the X direction. The rear surface 30b is an end surface at the rear end of the optical fiber holding component 30 located in the X direction. The front surface 30a and the rear surface 30b are, for example, planes along the YZ plane, and are arranged along the X direction. The upper surface 30c is an end surface at the upper end of the optical fiber holding component 30 located in the Z direction. The lower surface 30d is an end surface at the lower end of the optical fiber holding component 30 located in the Z direction. The upper surface 30c and the lower surface 30d are, for example, planes along the XY plane, and are arranged along the Z direction. The side surface 30e is an end surface at one end of the optical fiber holding component 30 located in the Y direction. The side surface 30f is an end surface at the other end of the optical fiber holding component 30 located in the Y direction. The side surface 30e and the side surface 30f are, for example, planes along the XZ plane, and are arranged along the Y direction.

[0085] The optical fiber holding member 30 has a fixing surface 30g for fixing the coating portions 13 of the plurality of optical fibers 10 together at a portion close to the rear surface 30b in the X direction. The fixing surface 30g is, for example, a plane along the XY plane, and is stepped relative to the upper surface 30c. The fixing surface 30g is connected to the upper surface 30c via a stepped surface 30s. The stepped surface 30s is, for example, a plane along the YZ plane, and is formed to be perpendicular to the fixing surface 30g and the upper surface 30c. The fixing surface 30g extends from the stepped surface 30s to the rear surface 30b in the X direction. The optical fiber holding member 30 has a plurality of V-grooves 30h for respectively holding the coating removal portions 12 of the plurality of optical fibers 10 at a portion close to the rear surface 30b in the X direction. The plurality of V-grooves 30h are formed on the upper surface 30c. The plurality of V-grooves 30h extend from the front surface 30a to the stepped surface 30s in the X direction on the upper surface 30c, and are arranged in an array along the Y direction.

[0086] like Fig.13As shown, the coating removal portions 12 of the plurality of optical fibers 10 are placed on the plurality of V-grooves 30h, respectively, and the coating portions 13 of the plurality of optical fibers 10 are placed on the fixing surface 30g. The coating removal portions 12 are placed on the respective V-grooves 30h, so that the positions of the optical fibers 10 relative to the YZ plane of the optical fiber holding member 30 are regulated. The optical fibers 10 are rotationally aligned in a state where the coating removal portions 12 are placed on the V-grooves 30h. Each V-groove 30h is configured to hold the coating removal portions 12 so as to be rotatable around the central axis L. In a state where all the optical fibers 10 that have been rotationally aligned are placed on the V-grooves 30h, respectively, an adhesive is applied to the optical fibers 10, and the coating removal portions 12 are pressed to the V-grooves 30h by the rectangular plate-shaped cover 31 provided on the coating removal portions 12. In this state, the adhesive is cured, and thereby the coating removal portions 12 are fixed to the V-grooves 30h via the adhesive. Similarly, the coating portion 13 is fixed to the fixing surface 30g via the adhesive. In this way, the optical fiber holding member 30 holding the plurality of optical fibers 10 is obtained.

[0087] Fig.16 2 is a cross-sectional view showing the state where the optical fiber holding component 30 is mounted on the ferrule 20B. Fig.16 As shown in FIG. 1 , the optical fiber holding member 30 holding a plurality of optical fibers 10 is arranged inside the ferrule 20B at a position opposite to the plurality of optical fiber holding portions 25C in the X direction. At this time, the lower surface 30d of the optical fiber holding member 30 is placed on the supporting surface 29a of the ferrule 20B, and the side surface 30e of the optical fiber holding member 30 hits the inner side surface 24a of the ferrule 20B. By aligning the lower surface 30d and the side surface 30e with the supporting surface 29a and the inner side surface 24a, respectively, the position of the optical fiber holding member 30 relative to the YZ plane of the ferrule 20B is determined, and the arrangement of the plurality of optical fibers 10 held by the optical fiber holding member 30 corresponds to the arrangement of the plurality of optical fiber holding portions 25C.

[0088] In this state, the optical fiber holding component 30 is advanced in the X direction, so that the coating removal portion 12 of each optical fiber 10 is inserted into the introduction hole 28C of the optical fiber holding component 25C. At this time, the posture of the optical fiber 10 is restricted by the optical fiber holding component 30 in the X direction, so the optical fiber 10 can be inserted straight into the introduction hole 28C. Then, the optical fiber holding component 30 is advanced in the X direction until the front surface 30a of the optical fiber holding component 30 hits the wall surface 26. As a result, Fig.13 As shown in FIG. 1 , the coating removal portion 12 is inserted into the holding hole 27 while the optical fiber 10 is maintained in the X direction. Then, the optical fiber holding member 30 holding the plurality of optical fibers 10 is fixed to the ferrule 20B via an adhesive, thereby obtaining Fig.13 The optical connector 1A is shown.

[0089] Even in such a form, the same effect as the optical connector 1 of the first embodiment can be obtained. That is, the coating removal portion 12 can be inserted into the holding hole 27 along the X direction in a state where friction between the coating removal portion 12 and the holding hole 27 is not likely to occur, so the occurrence of rotational deviation of the optical fiber 10 can be suppressed. As a result, the occurrence of positional deviation of the core 17 on the top surface 11 of the optical fiber 10 can be suppressed, and the occurrence of degradation of optical characteristics such as increase in connection loss can be suppressed. Moreover, in this embodiment, the optical fiber holding component 30 is arranged inside the ferrule 20B in a state where the plurality of optical fibers 10 that have been rotationally aligned are placed and fixed in the plurality of V-grooves 30h of the optical fiber holding component 30. As a result, the coating removal portions 12 of the plurality of optical fibers 10 can be inserted into the plurality of holding holes 27 together in a state where the postures of the plurality of optical fibers 10 are along the X direction. Thus, the possibility of friction between the holding hole 27 and the coating removal portion 12 can be more reliably reduced, and the installation work of the plurality of optical fibers 10 to the ferrule 20B can be facilitated. Furthermore, by placing the optical fiber holding member 30 on the support surface 29a, the posture of the optical fiber holding member 30 is stably maintained, and stress is not applied to the optical fiber 10. Furthermore, by holding both the coating removal portion 12 and the coating portion 13 by the optical fiber holding member 30, the posture of the optical fiber 10 can be further stabilized.

[0090] Fig.17 It is a cross-sectional view of an optical connector 1B according to a modified example of the second embodiment. Fig.18 1B is a perspective view of an optical fiber holding member 30A provided in the optical connector 1B. The optical connector 1B is provided with Fig.18 The optical fiber holding member 30A is replaced Fig.15 The optical fiber holding component 30A is different from the optical fiber holding component 30 and does not have a fixing surface 30g. The upper surface 30c extends from the front surface 30a to the rear surface 30b, and a plurality of V-grooves 30i formed on the upper surface 30c extend from the front surface 30a to the rear surface 30b. The coatings 13 of the plurality of optical fibers 10 are placed on the plurality of V-grooves 30i. Furthermore, the plurality of optical fibers 10 that have been rotationally aligned are respectively accommodated and fixed to the plurality of V-grooves 30i. A rectangular plate-shaped cover 31 that covers the coatings 13 of the plurality of optical fibers 10 is provided on the plurality of V-grooves 30i.

[0091] The ferrule 20C of the optical connector 1B has the same optical fiber holding portion 25 as in the first embodiment. The optical fiber holding member 30A is arranged inside the ferrule 20C at a position opposite to the optical fiber holding portion 25 in the X direction while holding the coating portions 13 of the plurality of optical fibers 10. Fig.17As shown, the coating portion 13 protruding forward from the optical fiber holding member 30A is inserted into the introduction hole 28 of the optical fiber holding part 25 , and the coating removal portion 12 protruding further forward from the coating portion 13 is inserted into the holding hole 27 of the optical fiber holding part 25 .

[0092] In this modification, similarly to the optical connector 1A of the second embodiment, the optical fiber holding member 30A is advanced on the support surface 29a, and the coating portion 13 is inserted into the introduction hole 28 and the coating removal portion 12 is inserted into the holding hole 27 while the posture of the optical fiber 10 is maintained along the X direction. Thereafter, the optical fiber holding member 30A holding the plurality of optical fibers 10 is fixed to the ferrule 20C via an adhesive, thereby obtaining Fig.17 Even in this form, the same effects as those of the optical connector 1A of the second embodiment can be obtained.

[0093] Fig.19 It is a cross-sectional view of an optical connector 1C according to another modified example of the second embodiment. Fig. 20 1C is a perspective view showing an optical fiber holding member 30B provided in the optical connector 1C. Fig. 20 The optical fiber holding member 30B is used instead Fig.15 The optical fiber holding component 30B is different from the optical fiber holding component 30 and does not have a fixing surface 30g. The upper surface 30c extends from the front surface 30a to the rear surface 30b. In addition, the optical fiber holding component 30B has a plurality of through holes 32 instead of the plurality of V-grooves 30h. The plurality of through holes 32 penetrate from the front surface 30a to the rear surface 30b in the X direction and are arranged along the Y direction. The plurality of optical fibers 10 are respectively inserted into the plurality of through holes 32.

[0094] like Fig.19 As shown, each through hole 32 has a small diameter portion 32a and a large diameter portion 32b. The coating removal portion 12 of the optical fiber 10 is inserted into the small diameter portion 32a. The inner diameter of the small diameter portion 32a is set to be the same as the outer diameter d1 of the coating removal portion 12, or slightly larger than the outer diameter d1 of the coating removal portion 12. The large diameter portion 32b has an inner diameter larger than the inner diameter of the small diameter portion 32a. The coating portion 13 of the optical fiber 10 is inserted into the large diameter portion 32b. The inner diameter of the large diameter portion 32b is set to be the same as the outer diameter d2 of the coating portion 13, or slightly larger than the outer diameter d2 of the coating portion 13. The optical fiber 10 is rotated and aligned in a state where the coating removal portion 12 and the coating portion 13 are respectively inserted into the small diameter portion 32a and the large diameter portion 32b, and the optical fiber 10 is fixed to the through hole 32 by the adhesive injected into the through hole 32.

[0095] The optical connector 1C includes the same ferrule 20B as that of the second embodiment. The optical fiber holding member 30B is arranged inside the ferrule 20B at a position facing the optical fiber holding portion 25C in the X direction while holding a plurality of optical fibers 10. Fig.19 As shown, the coating portion 13 protruding forward from the optical fiber holding member 30B is inserted into the introduction hole 28C of the optical fiber holding portion 25C, and the coating removal portion 12 protruding further forward from the coating portion 13 is inserted into the holding hole 27 of the optical fiber holding portion 25C.

[0096] In this modification, similarly to the optical connector 1A of the second embodiment, the optical fiber holding member 30B is advanced on the support surface 29a, and the coating portion 13 is inserted into the introduction hole 28C and the coating removal portion 12 is inserted into the holding hole 27 while the optical fiber 10 is kept in the X direction. Then, the optical fiber holding member 30B holding the plurality of optical fibers 10 is fixed to the ferrule 20B via an adhesive, thereby obtaining Fig.19 The optical connector 1C shown in the figure. Even in this form, the same effect as the optical connector 1A of the second embodiment can be obtained. The through hole 32 may have only the small diameter portion 32a, or the cover removal portion 12 may be held only by the small diameter portion 32a. Alternatively, the through hole 32 may have only the large diameter portion 32b, or the cover portion 13 may be held only by the large diameter portion 32b.

[0097] Fig.21 2 is a cross-sectional view showing a modified example of the optical fiber holding component 30. Fig.21 As shown, the optical fiber holding component 30C is a resin layer that covers the coating 13 of the plurality of optical fibers 10 at a time. The optical fiber holding component 30C constitutes a ribbon optical fiber including the plurality of optical fibers 10. The optical fiber holding component 30C is used to suppress positional changes between the plurality of optical fibers 10. The optical fiber holding component 30C integrally holds the coating 13 of the plurality of optical fibers 10 in a state where the plurality of optical fibers 10 are arranged side by side in the Y direction and are rotationally aligned. The optical fiber holding component 30C is arranged at a position opposite to the optical fiber holding portion 25 in the X direction, for example, inside the ferrule 20C, in a state where the plurality of optical fibers 10 are held. Even in such a form, the same effect as that of the optical connector 1A of the second embodiment can be obtained.

[0098] The present disclosure is not limited to the above-mentioned embodiments and modifications, and other various modifications are possible. For example, the above-mentioned embodiments and modifications may be combined with each other within the scope of no contradiction according to the desired purpose and effect. The structure of the optical connector is not limited to the above-mentioned embodiments and modifications. For example, the optical fiber holding portion of the ferrule may not have a tapered portion, or may only have a holding hole and an introduction portion. The introduction groove of the optical fiber holding portion is not limited to a V-groove, and may be a groove having other shapes such as a U-groove or a rectangular groove.

[0099] Description of Reference Numerals

[0100] 1, 1A, 1B, 1C: optical connector, 1a: first optical connector, 1b: second optical connector, 10: optical fiber, 11: top end surface, 12: coating removal portion, 13: coating portion, 15: resin coating, 16: cladding, 17: core, 17a: central core, 17b: peripheral core, 20, 20A, 20B, 20C: ferrule, 21: front end surface, 22: rear end surface, 22a: opening, 23: guide hole, 24: optical fiber accommodating portion, 24a: inner side surface, 25, 25A, 25B, 25C: optical fiber holding portion, 26: wall surface, 27: holding hole, 28, 28C: introduction hole (an example of “introduction portion”), 28A, 28B: introduction groove (an example of “introduction portion”), 28a: tapered portion, 2 8b: sizing portion, 29: optical fiber supporting portion, 29a: supporting surface, 30, 30A, 30B, 30C: optical fiber holding component, 30a: front surface, 30b: rear surface, 30c: upper surface, 30d: lower surface, 30e, 30f: side surface, 30g: fixing surface, 30h, 30i: V-groove, 30s: step surface, 31: cover, 32: through hole, 32a: thin diameter portion, 32b: thick diameter portion, 40: guide pin, 50: spacer, 50a: opening, 100: optical coupling structure, C1, C2, C3: imaginary circle, D1, D2, D4: inner diameter, D1, D2, D3: diameter, d1, d2: outer diameter, L: center axis, P1: connecting portion, S1, S2: inner wall surface, S2A, S2B: inner side surface.

Claims

1. An optical connector comprising: A plurality of optical fibers each having a coating removal portion obtained by removing a predetermined length of a resin coating from a top end surface and a coating portion in which the resin coating remains, and each having at least one of a core and a stress applying portion at a position offset from a central axis; as well as The ferrule has a front end face, a rear end face and a plurality of optical fiber holding parts, wherein: The front end face and the rear end face are arranged in a first direction extending from the central axis, the plurality of optical fiber holding portions extend between the front end face and the rear end face in the first direction, and are arranged in a second direction intersecting the first direction and respectively hold the plurality of optical fibers, The plurality of optical fiber holding parts respectively include: a holding hole into which the cover removed portion is inserted along the first direction and which holds the cover removed portion in a manner that maintains the position of the cover removed portion in a plane perpendicular to the first direction; and an introduction portion, located between the holding hole and the rear end surface, and having an inner wall surface inscribed with an imaginary circle, wherein the imaginary circle has a diameter larger than the inner diameter of the holding hole, A length of the holding hole in the first direction is shorter than a length of the introduction portion in the first direction.

2. The optical connector according to claim 1, wherein: The introduction portion is an introduction hole communicating with the holding hole in the first direction, The inner diameter of the introduction hole defined by the diameter of the imaginary circle is greater than or equal to the outer diameter of the covering portion, The covering portion is inserted into the introduction hole.

3. The optical connector according to claim 1, wherein: The introduction portion is an introduction hole communicating with the holding hole in the first direction, The inner diameter of the introduction hole defined by the diameter of the imaginary circle is equal to or greater than the outer diameter of the coating removal portion, Of the cover removed portion and the cover portion, only the cover removed portion is inserted into the introduction hole.

4. The optical connector according to claim 1, wherein: The introduction portion is an introduction groove communicating with the holding hole in the first direction, The diameter of the imaginary circle inscribed in the introduction groove is greater than or equal to the outer diameter of the coating removal portion, Of the cover removed portion and the cover portion, only the cover removed portion is accommodated in the introduction groove.

5. The optical connector according to claim 1, wherein: The introduction portion is an introduction groove communicating with the holding hole in the first direction, The diameter of the imaginary circle inscribed in the introduction groove is greater than or equal to the outer diameter of the covering portion, The covering portion is accommodated in the introduction groove.

6. The optical connector according to any one of claims 1 to 5, further comprising: The optical fiber holding member is arranged inside the ferrule at a position facing the plurality of optical fiber holding portions in the first direction, and holds the plurality of optical fibers.

7. The optical connector according to claim 6, wherein: The optical fiber holding member is a resin layer that collectively covers the coating portions of the plurality of optical fibers.

8. The optical connector according to claim 6, wherein: The optical fiber holding member has a plurality of V-grooves, wherein the plurality of V-grooves extend in the first direction and are arranged in the second direction to respectively accommodate the plurality of optical fibers.

9. The optical connector according to claim 6, wherein: The optical fiber holding member has a plurality of through holes, wherein the plurality of through holes penetrate in the first direction and are arranged in the second direction so as to allow the plurality of optical fibers to be inserted therethrough.

10. The optical connector according to any one of claims 1 to 9, wherein: The optical fiber is any one of a multi-core optical fiber, a polarization-maintaining optical fiber, and a bundled optical fiber.

11. A ferrule is a ferrule for holding a plurality of optical fibers, wherein: The plurality of optical fibers each have a coating removal portion obtained by removing a predetermined length of the resin coating from a top end surface and a coating portion where the resin coating remains, and each have at least one of a core and a stress applying portion at a position offset from a central axis, The ferrule has: Front face; a rear end surface, arranged with the front end surface in a first direction; as well as A plurality of optical fiber holding portions are configured to extend between the front end face and the rear end face in the first direction, and to be arranged in a second direction intersecting the first direction and to respectively hold the plurality of optical fibers, The plurality of optical fiber holding parts respectively include: a holding hole into which the cover removal portion is inserted along the first direction and configured to maintain a position of the cover removal portion in a plane perpendicular to the first direction; and an introduction portion, located between the holding hole and the rear end surface, and having an inner wall surface inscribed with an imaginary circle, wherein the imaginary circle has a diameter larger than the inner diameter of the holding hole, A length of the holding hole in the first direction is shorter than a length of the introduction portion in the first direction.

12. An optical coupling structure comprising a first optical connector and a second optical connector as the optical connectors according to any one of claims 1 to 10, The first optical connector is arranged to be opposed to the second optical connector in the first direction and optically coupled to the second optical connector.

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