Fiber strand fixing structure, optical submarine repeater, and method for assembling fiber strand fixing structure

Abstract

To provide a fiber strand fixing structure with which microbending losses do not occur when fixing a plurality of fiber strands in position in the inside of an optical submarine repeater.SOLUTION: A fiber strand fixing structure 100 comprises: a rod-like fiber cushion 10 which has a plurality of slits extending in the length direction on the outer circumference, and which is constituted to allow a fiber strand 200 to be inserted into each of the plurality of slits; and a cushion fixing unit 20 which has a hollow cylindrical structure and is constituted such that, when the fiber cushion 10 is press-fitted to a prescribed position in the hollow, the fiber cushion 10 is pushed and fixed in position from the outer circumference of the fiber cushion 10.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a bare fiber fixing structure, an optical submarine repeater, and a method for assembling the bare fiber fixing structure. [Background technology]

[0002] In recent years, the demand for international communications, including intercontinental communications, has been expanding rapidly. In addition, the recent increase in data traffic has led to a rapid spread of optical communications. In order to accommodate large-capacity transmission methods, there is a demand for high-performance communication devices for optical submarine cables. Since such optical submarine cables are quite long, optical submarine repeaters are installed at regular intervals to amplify optical signals (see, for example, Patent Document 1).

[0003] In the optical submarine repeater, a plurality of bare fibers extending from the upstream optical submarine cable and a plurality of bare fibers extending from the downstream optical submarine cable are accommodated. In order to accommodate the bare fibers in the optical submarine cable in the optical submarine repeater, a stable fixing structure that realizes low loss is required. Here, in order to prevent the occurrence of kinks due to pulling on the bare fibers drawn from the optical submarine repeater to the opposite optical submarine cable side, it is necessary to reliably fix these bare fibers in the optical submarine repeater. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-78677 A Summary of the Invention [Problem to be solved by the invention]

[0005] One possible method for fixing the optical fiber strands is to sandwich multiple optical fiber strands between two cushions from their sides and compress and fix them in place inside the housing. However, simply arranging multiple optical fiber strands between two cushions may result in any two optical fiber strands crossing each other inside the cushion. In such a case, microbending may occur at the point where the two optical fiber strands cross due to excessive pressure from the cushion, which may result in loss (microbending loss).

[0006] The present disclosure has been made to solve such problems, and an object of the present disclosure is to provide a fiber bare wire fixing structure, an optical submarine repeater, and a method for assembling a fiber bare wire fixing structure that can reliably prevent a plurality of fiber bare wires from being compressed and fixed in a crossed state. [Means for solving the problem]

[0007] The fiber strand fixing structure according to the first aspect of the present disclosure includes: a rod-shaped cushion having a plurality of slits extending in a length direction on an outer periphery thereof, the fiber strands being able to be inserted into the plurality of slits; a cushion fixing part having a hollow tubular structure and configured to press and fix the cushion from the outer periphery of the cushion when the cushion is press-fitted to a predetermined position in the hollow; It is equipped with the following.

[0008] An optical submarine repeater according to a second aspect of the present disclosure includes: A housing having a rectangular prism shape, one surface of which serves as a lid; Two flat cushions, The fiber bare wire fixing structure according to the first aspect, Equipped with The optical fiber fixing structure is fixed in the housing in a state where it is pressed by the two cushions from two directions relative to a direction perpendicular to the main surface of the lid.

[0009] A method for assembling a fiber bare wire fixing structure according to a third aspect of the present disclosure includes the steps of: a rod-shaped cushion having a plurality of slits extending in a length direction on an outer periphery thereof, the optical fiber being inserted into each of the plurality of slits; With the plurality of bare fiber wires inserted into the plurality of slits, respectively, the cushion is press-fitted to a predetermined position within the hollow space of a cushion fixing portion having a hollow cylindrical structure. Effect of the Invention

[0010] According to the present disclosure, it is possible to provide a fiber bare wire fixing structure, an optical submarine repeater, and a method for assembling a fiber bare wire fixing structure that can reliably prevent a plurality of fiber bare wires from being compressed and fixed in a crossed state within an optical submarine repeater. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view of an optical submarine repeater according to the present disclosure; [Diagram 2] 1 is a schematic cross-sectional view of a fiber strand fixing structure according to the present disclosure. [Diagram 3] 1A and 1B are schematic diagrams of a fiber cushion before a bare fiber is fixed thereto according to the present disclosure, in which (a) is a front view and (b) is a perspective view. [Figure 4] 13A and 13B are diagrams showing modified examples of a fiber cushion of the fiber strand fixing structure according to the present disclosure. [Diagram 5] FIG. 2 is a front view of a cushion fixing part before fixing a bare fiber according to the present disclosure. [Figure 6] 1A to 1C are diagrams showing a fiber bare wire arrangement step in the method for assembling the fiber bare wire fixing structure according to the present disclosure. [Figure 7] 1 is a diagram showing a preparation stage of a fiber cushion fixing step in the method of assembling a fiber bare wire fixing structure according to the present disclosure; FIG. [Figure 8] 11A and 11B are diagrams showing a state after a fiber cushion fixing step in the method of assembling a fiber bare wire fixing structure according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] (Embodiment) Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. However, the invention according to the claims is not limited to the following embodiment. In addition, all of the configurations described in the present embodiment are not necessarily essential as means for solving the problem. For clarity of explanation, the following description and drawings are omitted and simplified as appropriate. In each drawing, the same elements are given the same reference numerals, and repeated explanations are omitted as necessary.

[0013] <Optical undersea repeater> First, the configuration of an optical submarine repeater according to the present disclosure will be described with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view of an optical submarine repeater 1 according to the present disclosure. In the optical submarine repeater 1 of this embodiment, a fiber bare wire fixing structure 100, which will be described later, is housed in a housing main body 3 and fixed in a housing 5 by pressing with a lid 4. As shown in Fig. 1, the optical submarine repeater 1 includes the fiber bare wire fixing structure 100, two repeater cushions 2, and a housing 5 consisting of the housing main body 3 and the lid 4.

[0014] The housing 5 has a quadrangular prism shape, but the shape of the housing 5 is not limited to this. The housing 5 may have any shape, such as a cylindrical shape, as long as it can firmly fix the bare fiber fixing structure 100. If the housing 5 has another shape, the number and shape of the relay cushions 2 may be adjusted to match the shape.

[0015] As described above, the housing 5 has the housing body 3 and the lid 4. The housing body 3 has a box shape without a lid. The lid 4 forms one surface of the housing 5. When the optical submarine repeater 1 is in a completed state, the lid 4 is firmly fixed onto the housing body 3 to seal the inside of the optical submarine repeater 1 so that it can withstand the high water pressure at the bottom of the sea.

[0016] In this example, the two repeater cushions 2 are flat plates each having a main surface. The two repeater cushions 2 are disposed on the bottom of the housing 5 and on the top of the housing 5 via the fiber bare wire fixing structure 100 so that the main surfaces of the two repeater cushions 2 are in the same direction as the main surface of the cover 4 of the housing 5.

[0017] The material of the repeater cushion 2 may be any material that can firmly fix the fiber bare wire fixing structure 100, and may be, for example, rubber or sponge.

[0018] The fiber bare wire fixing structure 100 described below is installed in the optical submarine repeater 1. Specifically, the fiber bare wire fixing structure 100 is fixed in the housing 5 in a state where it is pressed by two repeater cushions 2, 2 from above and below in the vertical direction of the main surface of the lid portion 4 in FIG.

[0019] <Fiber strand fixing structure> Next, the configuration of the bare fiber fixing structure 100 according to the present disclosure will be described with reference to Figs. 2 to 5. Fig. 2 is a schematic cross-sectional view of the bare fiber fixing structure 100 according to the present disclosure. Fig. 3 is a schematic view of the fiber cushion 10 before fixing the bare fiber 200 according to the present disclosure, (a) being a front view thereof, and (b) being a perspective view thereof. Fig. 4 is a view showing a modified example of the fiber cushion 10 of the bare fiber fixing structure 100 according to the present disclosure. Fig. 5 is a front view of the cushion fixing part 20 before fixing the bare fiber 200 according to the present disclosure. The cross section of the bare fiber fixing structure 100 shown in Fig. 2 corresponds to the cross section of the bare fiber fixing structure 100 shown in Fig. 1.

[0020] The fiber bare wire fixing structure 100 of this embodiment is fixed inside the housing 5 of the optical submarine repeater 1, thereby fixing a plurality of fiber bare wires 200 inside the optical submarine repeater 1. As shown in FIG. 2, the fiber bare wire fixing structure 100 includes a fiber cushion 10 and a cushion fixing portion 20.

[0021] 3, the fiber cushion 10 is a rod-like cushion having a cylindrical shape, and has a plurality of slits 11 extending in the longitudinal direction on its outer periphery. In this example, the fiber cushion 10 has four slits 11 at equal intervals to fix four bare fibers 200 spaced apart from one another by the bare fiber fixing structure 100.

[0022] Each slit 11 has an opening whose cross section is substantially V-shaped. Then, as described later, in the process of assembling the bare fiber fixing structure 100, a bare fiber 200 is inserted into each of the openings of the slits 11.

[0023] The cross-sectional shape of the opening of the slit 11 is not limited to a substantially V-shape. For example, as shown in FIG. 4, the cross-sectional shape may be a substantially U-shape. That is, the fiber cushion 10 may have a plurality of slits 12 extending in the length direction instead of the slit 11. In this case, the bottom of the substantially U-shape, i.e., the curved surface portion of the slit 12 toward the center of the fiber cushion 10, may have a size that substantially matches the outer periphery of the fiber strand 200. By configuring the slit 12 in this way, the outer periphery of the fiber strand 200 comes into contact with the inner surface of the slit 12 more than in the case of the slit 11. This makes it possible to more evenly distribute the load from the fiber cushion 10 to the fiber strand 200.

[0024] The material of the fiber cushion 10 may be any material as long as each of the fiber strands 200 is firmly fixed after the fiber strand fixing structure 100 is assembled and excessive pressure is not applied to the fiber strands 200. The material of the fiber cushion 10 may be, like the repeater cushion 2, rubber or sponge, for example.

[0025] In this embodiment, the fiber cushion 10 has a cylindrical shape, but the shape of the fiber cushion 10 is not limited to this. As long as the load on the fiber strands 200 after the fiber strand fixing structure 100 is assembled is approximately uniform, the fiber cushion 10 may have a prismatic shape such as a quadrangle depending on the number of fiber strands 200 to be fixed, and more preferably, a regular polygonal prismatic shape.

[0026] 2 and 5, the cushion fixing part 20 is a hollow cylindrical (ring-shaped) mechanical component having a cylindrical shape. The cushion fixing part 20 is provided at one end in the axial direction with a tapered part 21 that gradually narrows from the one end to the other end (see FIG. 7). As will be described later, this tapered part 21 is used when inserting (press-fitting) the fiber cushion 10 into the hollow of the cushion fixing part 20.

[0027] The material of the cushion fixing part 20 is not particularly limited, but it is sufficient if it has the strength to press the fiber cushion 10 into the hollow interior. As will be described later, the cushion fixing part 20 is configured so that when the fiber cushion 10 is press-fitted to a predetermined position in the hollow interior of the cushion fixing part 20 using the tapered part 21, the fiber cushion 10 is pressed from the outer periphery of the fiber cushion 10 to be fixed.

[0028] When the outer periphery of the fiber cushion 10 is pressed and the fiber cushion 10 is fixed within the cushion fixing portion 20, the fiber strands 200 inserted into each of the multiple slits 11 or 12 are fixed within the slits 11 or 12 by pressure from the cross section (inner surface) of the corresponding slit 11 or 12 while spaced apart from each other, without touching the inner wall of the cushion fixing portion 20.

[0029] <How to assemble the fiber bare wire fixing structure> Next, a method for assembling a bare fiber fixing structure according to the present disclosure will be described with reference to Figs. 6 to 8. Fig. 6 is a diagram showing a bare fiber arrangement step in the method for assembling a bare fiber fixing structure 100 according to the present disclosure. Fig. 7 is a diagram showing a state in a preparation stage for a fiber cushion fixing step in the method for assembling a bare fiber fixing structure 100 according to the present disclosure. Fig. 8 is a diagram showing a state after the fiber cushion fixing step in the method for assembling a bare fiber fixing structure 100 according to the present disclosure. In this example, a case will be described where a fiber cushion 10 having the slit 11 of Fig. 3 is used.

[0030] The method for assembling the fiber bare wire fixing structure 100 includes at least a fiber bare wire arrangement step and a fiber cushion fixing step. In the fiber bare wire arrangement step, first, a plurality of fiber bare wires 200 and a fiber cushion 10 are prepared. Then, as shown in Fig. 6, the fiber bare wires 200 are inserted into each slit 11 of the fiber cushion 10, thereby arranging the plurality of fiber bare wires 200 on the fiber cushion 10.

[0031] Next, in the fiber cushion fixing step, first, the cushion fixing part 20 is prepared. At this time, as shown in Fig. 7, the fiber cushion 10 into which the multiple fiber strands 200 are inserted and the cushion fixing part 20 are arranged so that the tapered part 21 of the cushion fixing part 20 faces the fiber cushion 10. In this case, the multiple fiber strands 200 arranged in the slit 11 penetrate the hollow interior of the cushion fixing part 20.

[0032] Then, with the multiple fiber strands 200 inserted into the multiple slits 11, respectively, the fiber cushion 10 with the multiple fiber strands 200 inserted therein is moved in the X direction shown in Fig. 7 while the cushion fixing part 20 is fixed. When one end side of the length direction of the fiber cushion 10 comes into contact with the tapered part 21 of the cushion fixing part 20, the one end side is compressed so as to fit along the inner surface of the tapered part 21, while the fiber cushion 10 is moved.

[0033] Finally, as shown in Fig. 8, the fiber cushion 10 with the multiple fiber strands 200 inserted therein is pressed into a predetermined position in the hollow of the cushion fixing portion 20 to complete the assembly of the fiber strand fixing structure 100. As a result, the fiber cushion 10 is substantially evenly compressed, and each fiber strand 200 is fixed individually. Here, the predetermined position refers to a position where the fiber cushion 10 has completely passed through the tapered portion 21 and the entire outer periphery of the fiber cushion 10 is in pressure contact with the inner surface of the cushion fixing portion 20. For this reason, the length of the cushion fixing portion 20 excluding the tapered portion 21 is set to be longer than the length of the fiber cushion 10 by a predetermined length or more.

[0034] Although not shown in the drawings, the method of assembling the optical submarine repeater 1 is as follows: That is, as shown in Fig. 1, after further preparing two repeater cushions 2 and a housing main body 3, one repeater cushion 2 is installed on the bottom of the housing main body 3, the optical fiber fixing structure 100 assembled as described above is placed on the repeater cushion 2, and another repeater cushion 2 is placed on the optical fiber fixing structure 100. Then, after further preparing a lid 4, the lid 4 is positioned so as to fit onto the housing main body 3.

[0035] Thereafter, pressure is slowly applied downward to the lid 4 so that the two repeater cushions 2 are gradually crushed by the fiber bare wire fixing structure 100. Finally, when the lid 4 completely reaches the housing main body 3, the lid 4 is fixed onto the housing main body 3 to seal the inside of the optical submarine repeater 1 and complete the assembly of the optical submarine repeater 1.

[0036] As described above, the fiber bare wire fixing structure 100 of the present disclosure is configured to include a rod-shaped fiber cushion (cushion) 10 having a plurality of slits 11 or 12 extending in the length direction on its outer periphery and configured to allow the fiber bare wire 200 to be inserted into each of the plurality of slits 11 or 12, and a cushion fixing part 20 having a hollow cylindrical structure and configured to press and fix the fiber cushion 10 from the outer periphery of the fiber cushion 10 when the fiber cushion 10 is pressed into a predetermined position in the hollow. By configuring the fiber bare wire fixing structure 100 in this way, the plurality of fiber bare wires 200 can be fixed while being spaced apart from each other. This can reliably prevent the plurality of fiber bare wires 200 from being compressed and fixed in the optical submarine repeater 1 in a crossed state. Therefore, it is possible to effectively prevent the occurrence of microbends due to excessive pressing of the crossed fiber bare wires.

[0037] Furthermore, the cushion fixing part 20 may be provided at one axial end thereof with a tapered part 21 that gradually narrows toward the other axial end thereof. By providing the cushion fixing part 20 with the tapered part 21, the fiber bare wire fixing structure 100 can be easily assembled.

[0038] Moreover, the optical submarine repeater 1 of the present disclosure comprises a housing 5 having a rectangular prism shape with one surface serving as the lid 4, two flat repeater cushions (cushions) 2, 2, and the above-described fiber bare wire fixing structure 100, and the fiber bare wire fixing structure 100 is configured to be fixed within the housing 5 in a state where it is pressed by the two repeater cushions 2, 2 from two directions relative to the perpendicular direction of the main surface of the lid 4. By configuring the optical submarine repeater 1 in this manner, it is possible to prevent the occurrence of kinks due to pulling on the fiber bare wire 200, while achieving the same effect as that achieved by using the fiber bare wire fixing structure 100.

[0039] Furthermore, the method of assembling the fiber bare wire fixing structure 100 of the present disclosure is configured to insert the fiber bare wires 200 into each of the multiple slits 11 or 12 of a rod-shaped fiber cushion (cushion) 10 having multiple slits 11 or 12 extending in the length direction on its outer periphery, and then press the fiber cushion 10 into a predetermined position within the hollow of the cushion fixing part 20 having a hollow cylindrical structure with the multiple fiber bare wires 200 inserted into each of the multiple slits 11 or 12. By configuring the method of assembling the fiber bare wire fixing structure 100 in this manner, it is possible to achieve the same effect as that achieved by using the fiber bare wire fixing structure 100.

[0040] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by a person skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure.

[0041] Each drawing is merely an example for illustrating one or more embodiments or variations. Each drawing may relate not only to one particular embodiment, but to one or more other embodiments. As will be appreciated by those skilled in the art, various features described with reference to any one drawing may be combined with features shown in one or more other drawings to create an embodiment not expressly shown or described, for example. Not all features shown in any one drawing are necessary to describe an exemplary embodiment, and some features may be omitted.

[0042] Although the present invention has been described with reference to the embodiment, the present invention is not limited to the above embodiment and can be modified as appropriate without departing from the spirit of the present invention.

[0043] A part or all of the above-described embodiments can be described as, but is not limited to, the following supplementary notes. (Appendix 1) a rod-shaped cushion having a plurality of slits extending in a length direction on an outer periphery thereof, the fiber strands being able to be inserted into the plurality of slits; a cushion fixing part having a hollow tubular structure and configured to press and fix the cushion from the outer periphery of the cushion when the cushion is press-fitted to a predetermined position in the hollow; A fiber strand fixing structure comprising: (Appendix 2) The cushion has a cylindrical shape, The cushion fixing portion has a cylindrical shape. 2. The optical fiber fixing structure according to claim 1. (Appendix 3) A tapered portion is provided on one axial end side of the cushion fixing portion, the tapered portion gradually narrowing toward the other axial end side. 3. The optical fiber fixing structure according to claim 2. (Appendix 4) The cross section of each of the plurality of slits is substantially V-shaped or substantially U-shaped. 4. A fiber strand fixing structure according to claim 1. (Appendix 5) When the outer periphery of the cushion is pressed and the cushion is fixed in the cushion fixing part, the optical fiber inserted into each of the plurality of slits is fixed in the corresponding slit by pressure from a cross section of the slit without touching the cushion fixing part. 5. The optical fiber fixing structure according to claim 4. (Appendix 6) The optical fiber fixing structure is installed in an optical submarine repeater. 4. A fiber strand fixing structure according to claim 1. (Appendix 7) A housing having a rectangular prism shape, one surface of which serves as a lid; A fiber bare wire fixing structure according to any one of Supplementary Note 1 to Supplementary Note 3, Two cushions having the same main surface as the main surface of the lid of the housing; Equipped with the fiber bare wire fixing structure is fixed in the housing in a state where it is pressed by the two cushions from above and below in a direction perpendicular to the main surface of the lid portion; Optical undersea repeater. (Appendix 8) a rod-shaped cushion having a plurality of slits extending in a length direction on an outer periphery thereof, the optical fiber being inserted into each of the plurality of slits; With the plurality of fiber strands inserted into the plurality of slits, the cushion is press-fitted to a predetermined position within the hollow of a cushion fixing part having a hollow cylindrical structure. A method for assembling a fiber bare wire fixing structure. (Appendix 9) The cushion has a cylindrical shape, The cushion fixing portion has a cylindrical shape. A method for assembling the optical fiber fixing structure described in appendix 8. (Appendix 10) A tapered portion is provided on one axial end side of the cushion fixing portion, the tapered portion gradually narrowing toward the other axial end side, the cushion in a state in which the plurality of bare fiber wires are inserted into the plurality of slits, respectively, is press-fitted into the cushion fixing part from the side where the tapered part is provided; A method for assembling the optical fiber fixing structure described in appendix 9. (Appendix 11) The cross section of each of the plurality of slits is substantially V-shaped or substantially U-shaped. A method for assembling a fiber strand fixing structure according to any one of claims 8 to 10. (Appendix 12) When the cushion is fixed to the cushion fixing portion, the optical fiber inserted into each of the plurality of slits is fixed in the corresponding slit by pressure from a cross section of the slit without touching the cushion fixing portion. A method for assembling the optical fiber fixing structure according to claim 11. (Appendix 13) The assembled optical fiber fixing structure is installed in an optical submarine repeater. A method for assembling a fiber strand fixing structure according to any one of claims 8 to 10. [Explanation of symbols]

[0044] 1. Optical submarine repeater 2. Repeater cushion 3. Main body 4 Lid 5. Cabinet 10 Fiber Cushion 11 Slit 20 Cushion fixing part 21 Tapered section 100 Fiber Wire Fixing Structure 200 Fiber Bare Wire

Claims

1. a rod-shaped cushion having a plurality of slits extending in a length direction on an outer periphery thereof, the fiber strands being able to be inserted into the plurality of slits; a cushion fixing part having a hollow tubular structure and configured to press and fix the cushion from the outer periphery of the cushion when the cushion is press-fitted to a predetermined position in the hollow; A fiber strand fixing structure comprising:

2. The cushion has a cylindrical shape, The cushion fixing portion has a cylindrical shape. The optical fiber fixing structure according to claim 1 .

3. A tapered portion is provided on one axial end side of the cushion fixing portion, the tapered portion gradually narrowing toward the other axial end side. The optical fiber fixing structure according to claim 2 .

4. A cross section of each of the plurality of slits is substantially V-shaped or substantially U-shaped.

4. The optical fiber fixing structure according to claim 1.

5. When the outer periphery of the cushion is pressed and the cushion is fixed in the cushion fixing part, the optical fiber inserted into each of the plurality of slits is fixed in the corresponding slit by pressure from a cross section of the slit without touching the cushion fixing part.

5. The optical fiber fixing structure according to claim 4.

6. A housing having a rectangular prism shape, one surface of which serves as a lid; Two flat cushions, A fiber bare wire fixing structure according to any one of claims 1 to 3, Equipped with the fiber bare wire fixing structure is fixed in the housing in a state where it is pressed by the two cushions from two directions with respect to a direction perpendicular to a main surface of the lid portion; Optical undersea repeater.

7. a rod-shaped cushion having a plurality of slits extending in a length direction on an outer periphery thereof, the optical fiber being inserted into each of the plurality of slits; With the plurality of fiber strands inserted into the plurality of slits, the cushion is press-fitted to a predetermined position within the hollow space of a cushion fixing part having a hollow cylindrical structure. A method for assembling a fiber bare wire fixing structure.

8. The cushion has a cylindrical shape, The cushion fixing portion has a cylindrical shape. A method for assembling the optical fiber fixing structure according to claim 7.

9. A tapered portion is provided on one axial end side of the cushion fixing portion, the tapered portion gradually narrowing toward the other axial end side, the cushion in a state in which the plurality of bare fibers are inserted into the plurality of slits, respectively, is press-fitted into the cushion fixing portion from the side where the tapered portion is provided; A method for assembling the optical fiber fixing structure according to claim 8.

10. A cross section of each of the plurality of slits is substantially V-shaped or substantially U-shaped, In a state where the cushion is fixed to the cushion fixing portion, the optical fiber inserted into each of the plurality of slits is fixed in the corresponding slit by pressure from a cross section of the slit without touching the cushion fixing portion. A method for assembling the optical fiber fixing structure according to any one of claims 7 to 9.

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