Optical cable structure and method for manufacturing the optical cable structure

Abstract

This optical cable structure is equipped with a plurality of connector-equipped optical fibers (1) which are housed in a tubular member (100) and are drawn out from an end section of a sheath (S) of an optical cable (C). The plurality of connector-equipped optical fibers (1) are each equipped with a drawn optical fiber (2) which is drawn from the end section of a sheath (S) and an optical connector (3) which is provided to the tip end section of the drawn optical fiber (2). The lengths of the plurality of drawn optical fibers (2) are different.　The plurality of drawn optical fibers (2) each have a base end-side optical fiber (5) positioned on the sheath (S) end section side, a tip end-side optical fiber (6) positioned on the optical connector (3) side, and a connecting section (7) for connecting the base end-side optical fiber (5) and the tip end-side optical fiber (6) to one another. The plurality of connecting sections (7) are located inside the tubular member (100) in the state in which the plurality of connector-equipped optical fibers (1) are housed by the tubular member (100).

Description

[Technical field]

[0001] The present invention relates to an optical cable structure and a method for manufacturing an optical cable structure. This application claims priority to Patent Application No. 2021-199309, filed in Japan on December 8, 2021, the contents of which are incorporated herein by reference. [Background technology]

[0002] Conventionally, when laying optical wiring by inserting an optical cable into a duct, the tip of the optical cable is housed in a tubular member (pulling end) for protection. A plurality of optical fibers, each terminated with an optical connector, may be housed inside the tubular member as the tip of the optical cable. Patent Document 1 discloses an optical cable structure in which the lengths of the optical fibers constituting the tip portion of the optical cable are made different, and the optical connectors terminated to the optical fibers are arranged shifted in the length direction of the optical fibers (optical cable). In such an optical cable structure, the optical connectors are prevented from becoming bulky in the radial direction of the optical cable, and the diameter dimension of the tubular member that houses the optical connectors can be kept small. Therefore, even if there are a large number of optical fibers with optical connectors at the tip portion, the optical cable can be inserted into a thin duct. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2002-333561 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when manufacturing the optical cable structure disclosed in Patent Document 1, it is difficult to efficiently perform the work of terminating the optical connectors to the respective tips of the multiple optical fibers. For example, in order to efficiently perform the work of terminating the optical connectors, it is preferable to align the positions of the tips of the multiple optical fibers, but since the lengths of the multiple optical fibers are different, it is difficult to align the positions of the tips of the multiple optical fibers.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide an optical cable structure and a manufacturing method for an optical cable structure that makes it possible to easily perform the termination work of optical connectors to multiple optical fibers that constitute the tip portion of an optical cable housed in a tubular member. [Means for solving the problem]

[0006] An optical cable structure according to one aspect of the present invention is an optical cable structure having a plurality of connectorized optical fibers led out from an end of a sheath of an optical cable and housed in a tubular member having a predetermined length, wherein each of the plurality of connectorized optical fibers includes an outgoing optical fiber led out from an end of the sheath and an optical connector provided at a tip end of the outgoing optical fiber in a lead-out direction. At least some of the outgoing optical fibers led out from the end of the sheath have different lengths. Each of the plurality of outgoing optical fibers includes a base end optical fiber located on the end side of the sheath, a tip end optical fiber located on the optical connector side, and a connection portion connecting the base end optical fiber and the tip end optical fiber. When the plurality of connectorized optical fibers are housed in the tubular member, the connection portion of the plurality of outgoing optical fibers is located inside the tubular member.

[0007] A method for manufacturing an optical cable structure according to one aspect of the present invention is a method for manufacturing an optical cable structure having a plurality of connectorized optical fibers led out from an end of a sheath of an optical cable and housed in a tubular member having a predetermined length, the method comprising: a first step of terminating an optical connector to a first longitudinal end of a distal optical fiber, a second step of leading out a plurality of base optical fibers from the end of the sheath, and a third step of, after the first and second steps, connecting second longitudinal ends of the plurality of distal optical fibers to distal ends of the plurality of base optical fibers, respectively, to form a plurality of connectorized optical fibers extending from an end of the sheath, the plurality of connectorized optical fibers having lead-out optical fibers constituted by the base optical fiber and the distal optical fiber and the optical connector. At least one of the lengths of the plurality of distal optical fibers and the lengths of the plurality of base optical fibers is set before the third step so that the lengths of at least some of the lead-out optical fibers led out from the end of the sheath are different. Effect of the Invention

[0008] According to the present invention, the end portion of an optical cable is formed, and the operation of terminating an optical connector to a plurality of outgoing optical fibers housed in a tubular member can be easily performed. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing an optical cable structure according to a first embodiment of the present invention and a state in which a plurality of optical fibers with connectors constituting the optical cable structure are housed in a tubular member. [Diagram 2] FIG. 2 is a perspective view showing a state in which a plurality of optical fibers with connectors are taken out of a tubular member in FIG. [Diagram 3] FIG. 3 is an enlarged perspective view of the connectorized optical fiber of FIGS. 1 and 2. [Figure 4] FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. [Diagram 5] 4 is a cross-sectional view taken along the arrows VV in FIG. 3. [Figure 6] FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. [Figure 7] FIG. 4 is an exploded perspective view of the connectorized optical fiber of FIG. [Figure 8] 1A to 1C are diagrams illustrating a manufacturing process of an optical cable structure according to a first embodiment of the present invention. [Figure 9] 5 is a cross-sectional view showing an optical cable structure according to a second embodiment of the present invention and a state in which a plurality of optical fibers with connectors constituting the optical cable structure are housed in a tubular member. FIG. [Figure 10] 10 is an enlarged plan view showing the connectorized optical fiber of FIG. 9. FIG. [Figure 11] 11 is a perspective view showing a state in which the connectorized optical fiber of FIG. 10 has been separated into a base end side optical fiber, a tip end side optical fiber, and a fusion spliced ​​portion. FIG. [Figure 12] 5A to 5C are diagrams illustrating a manufacturing process of an optical cable structure according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 and 2, the optical cable structure of the first embodiment has a plurality of optical fibers with connectors 1 that are led out from an end of a sheath S of an optical cable C and form a tip portion of the optical cable C. In the illustrated example, the number of optical fibers with connectors 1 is three, but is not limited to this. The plurality of optical fibers with connectors 1 are housed in a tubular member 100 having a predetermined length.

[0011] As shown in Fig. 1, the tubular member 100 covers a plurality of connectorized optical fibers 1. The tubular member 100 plays a role of protecting the plurality of connectorized optical fibers 1 when the optical cable C is passed through a duct or the like of a building. The tubular member 100 also plays a role of a pulling end that is pulled when the optical cable C is passed through the duct or the like. The tubular member 100 is removed from the optical cable C after the optical cable C is passed through the duct or the like.

[0012] The tubular member 100 has a tubular body 101 and a head 102. The tubular body 101 is formed in a tubular shape to accommodate the connector-equipped optical fiber 1. The tubular body 101 may be flexible, for example. The head 102 is provided at the tip of the tubular body 101 and covers an opening on the tip side of the tubular body 101. A pulling eye 103 is provided at the tip of the head 102. By tying a rope or the like to the pulling eye 103 and pulling it, it becomes easier to pass the optical cable C through a duct or the like. The tubular member 100 is detachably attached to the optical cable C by accommodating multiple optical fibers 1 with connectors in the tubular body 101 and holding the base end of the tubular body 101 in a holder 105 fixed to the end of the sheath S by a screw or the like.

[0013] As shown in Figures 1 to 3, each connectorized optical fiber 1 of the optical cable C has an output optical fiber 2 output from the end of the sheath S, and an optical connector 3 provided at the tip of the output optical fiber 2 in the output direction. The output optical fiber 2 has cores 52, 62 (see Figs. 4 to 6) for transmitting an optical signal. The number of cores 52, 62 in the output optical fiber 2 may be, for example, one, but is plural in this embodiment.

[0014] The output optical fiber 2 includes a base end side optical fiber 5, a tip end side optical fiber 6, and a connection portion .

[0015] The base-side optical fiber 5 is a base-side portion of the derived optical fiber 2 located on the end side of the sheath S. As shown in Fig. 4, the base-side optical fiber 5 in this embodiment is a multi-core fiber 51 having a plurality of cores 52 (seven in the illustrated example). The multiple cores 52 constituting the multi-core fiber 51 are arranged on the same circumference centered on the axis C1 of the base-side optical fiber 5 when viewed from the longitudinal direction of the base-side optical fiber 5, and are arranged at intervals around the axis C1. In the multi-core fiber 51 in the illustrated example, one core 52 is arranged on the axis C1 of the base-side optical fiber 5.

[0016] 1 to 3, the tip side optical fiber 6 is a portion on the tip side of the lead-out optical fiber 2 located on the optical connector 3 side. As shown in Fig. 5 and Fig. 6, the tip side optical fiber 6 in this embodiment is composed of a plurality of (seven in the illustrated example) single-core fibers 61 each having one core 62. The number of single-core fibers 61 constituting the tip side optical fiber 6 corresponds to the number of cores 52 (see Fig. 4) of the multi-core fiber 51 constituting the base side optical fiber 5.

[0017] As shown in Fig. 3, at the base end (second end) 6B in the longitudinal direction of the tip side optical fiber 6 located on the base end side optical fiber 5 side, as shown in Fig. 5, a plurality of single core fibers 61 are arranged so as to correspond to the arrangement of the plurality of cores 52 of the base end side optical fiber 5 shown in Fig. 4. Specifically, at the base end of the tip side optical fiber 6, the plurality of single core fibers 61 are arranged on the same circumference centered on a predetermined axis C2 as shown in Fig. 5. Moreover, one single core fiber 61 is arranged so as to be located on the predetermined axis C2.

[0018] On the other hand, at a longitudinal tip portion (first end portion) 6A of the tip side optical fiber 6 located on the optical connector 3 side as shown in Fig. 3, a plurality of single-core fibers 61 are arranged so as to correspond to the optical connector 3 (ferrule) as shown in Fig. 6. Specifically, at the tip portion of the tip side optical fiber 6, a plurality of single-core fibers 61 are arranged in a line in a linear direction (left-right direction in Fig. 6) perpendicular to the longitudinal direction as shown in Fig. 6.

[0019] 1 to 3, the connection portion 7 connects the base end side optical fiber 5 and the tip end side optical fiber 6. The connection portion 7 has a role of optically coupling the multiple cores 52 (see FIG. 4) of the base end side optical fiber 5 and the multiple cores 62 (see FIG. 5) of the tip end side optical fiber 6 individually. The connection portion 7 in this embodiment is a connector connection portion 71 that mechanically connects the base end side optical fiber 5 and the tip end side optical fiber 6.

[0020] As shown in FIGS. 3 and 7, the connector connection portion 71 has a base end connector 72, a tip end connector 73, and an adapter 74. The proximal connector 72 is provided at the tip of the proximal optical fiber 5, and has a connection surface 721 from which the tip of the proximal optical fiber 5 is exposed. Although not shown, an insertion hole is formed in the proximal connector 72. The tip of the proximal optical fiber 5 is inserted into this insertion hole and exposed from the connection surface 721 of the proximal connector 72. The tip side connector 73 is provided at the base end of the tip side optical fiber 6, and has a connection surface 731 from which the base end of the tip side optical fiber 6 is exposed. Although not shown, an insertion hole is formed in the tip side connector 73. The base end of the tip side optical fiber 6 is inserted into this insertion hole and exposed from the connection surface 731 of the tip side connector 73.

[0021] The adapter 74 connects the base connector 72 and the tip connector 73, and optically couples the core 52 of the base optical fiber 5 (see FIG. 4) and the core 62 of the tip optical fiber 6 (see FIG. 5). The adapter 74 of this embodiment is formed in a cylindrical shape with both axial ends open. The base connector 72 and the tip connector 73 are inserted into the openings at both ends of the adapter 74 so that the connection surfaces 721, 731 of the base connector 72 and the tip connector 73 face each other. This allows the connection surfaces 721, 731 of the base connector 72 and the tip connector 73 to be butted against each other, and the core 52 of the base optical fiber 5 and the core 62 of the tip optical fiber 6 to be optically coupled.

[0022] 1 and 2, the lengths of the multiple output optical fibers 2 output from the end of the sheath S are different. In this embodiment, the lengths of all the output optical fibers 2 are different. In addition, the lengths of the multiple base-end side optical fibers 5 constituting the multiple output optical fibers 2 are different. Furthermore, the lengths of the plurality of tip side optical fibers 6 constituting the plurality of lead-out optical fibers 2 are equal. Since the multiple base-side optical fibers 5 that constitute the multiple output optical fibers 2 have different lengths, the multiple connection portions 7 (connector connection portions 71) located at the respective tips of the multiple base-side optical fibers 5 are positioned offset in the output direction of the output optical fiber 2.

[0023] The optical connector 3 is provided at the tip of each leading optical fiber 2 in the leading-out direction, that is, at the tip of each tip-side optical fiber 6. As shown in FIG. 3, the optical connector 3 has a connection end face 31 to which the tip of the tip-side optical fiber 6 is exposed. Although not shown, an insertion hole is formed in the optical connector 3. The tip of the tip-side optical fiber 6 is inserted into this insertion hole and exposed from the connection end face 31 of the optical connector 3. In this embodiment, the insertion hole of the optical connector 3 is formed to insert a plurality of single-core fibers 61 (see FIG. 6) constituting the tip-side optical fiber 6 while these single-core fibers 61 are aligned in a linear direction perpendicular to the longitudinal direction. As described above, the lengths of the multiple output optical fibers 2 output from the end of the sheath S are different. Therefore, the multiple optical connectors 3 provided at the respective tips of the multiple output optical fibers 2 are positioned offset in the output direction of the output optical fibers 2.

[0024] As shown in FIG. 1, in a state in which a plurality of connectorized optical fibers 1 of an optical cable C are housed in a tubular member 100 , the connection portions 7 of all of the output optical fibers 2 are located inside the tubular member 100 . Furthermore, the length of all of the connectorized optical fibers 1 is shorter than the length of the tubular member 100. This allows the connectorized optical fibers 1 to be housed in the tubular member 100 without bending any of the lead-out optical fibers 2.

[0025] Next, a method for manufacturing the optical cable structure of this embodiment will be described. When manufacturing an optical cable structure, first, as shown in Fig. 7 and Fig. 8, an optical connector 3 is terminated to a first end (tip portion) 6A in the longitudinal direction of a tip side optical fiber 6 (first step). The termination work of the optical connector 3 in the first step includes an insertion work of inserting the tip side optical fiber 6 into the optical connector 3, a polishing work of polishing the connection end face 31 of the optical connector 3 and the tip of the tip side optical fiber 6 exposed to this connection end face 31, and an inspection work of inspecting the optical loss of the tip of the tip side optical fiber 6 exposed to the connection end face 31. In addition, in the first step of this embodiment, a tip side connector 73 is terminated to a second end (base end) 6B of the tip side optical fiber 6. The termination work of the tip side connector 73 may include an insertion work, a polishing work, and an inspection work similar to the termination work of the optical connector 3 described above. The first step is performed on the plurality of distal end optical fibers 6. In this embodiment, before the first step, the lengths of the plurality of distal end optical fibers 6 are set in advance so that the lengths of the plurality of distal end optical fibers 6 are equal to each other.

[0026] Moreover, when manufacturing the optical cable structure, a plurality of base-side optical fibers 5 are led out from an end of the sheath S of the optical cable C (second step). In the second step of this embodiment, the lengths of the plurality of base-side optical fibers 5 are set so that the lengths of the plurality of base-side optical fibers 5 are different. In the second step of this embodiment, a base-side connector 72 is terminated to the tip of the base-side optical fiber 5. The termination work of the base-side connector 72 may include the same insertion work, polishing work, and inspection work as described above. The second step may, for example, be carried out before or after the first step, or simultaneously with the first step.

[0027] After the first and second steps, as shown in Figures 2 and 3, second ends (base ends) 6B of the multiple distal optical fibers 6 are respectively connected to the distal ends of the multiple proximal optical fibers 5 (third step). By carrying out this third step, a lead-out optical fiber 2 having the proximal optical fiber 5 and the distal optical fiber 6 is formed. In addition, a connectorized optical fiber 1 having the lead-out optical fiber 2 and the optical connector 3 and extending from the end of the sheath S is formed. In the third step of this embodiment, the base end side optical fiber 5 and the tip end side optical fiber 6 are connected by the connector connection part 71. Specifically, by using an adapter 74, a base end side connector 72 provided at the tip end of the base end side optical fiber 5 and a tip end side connector 73 provided at the second end (base end) 6B of the tip end side optical fiber 6 are butted together, whereby the base end side optical fiber 5 and the tip end side optical fiber 6 are connected.

[0028] In the manufacturing method of this embodiment, as described above, before the first step, the lengths of the plurality of distal optical fibers 6 are set so that the lengths of the plurality of distal optical fibers 6 are equal. In addition, in the second step, the lengths of the plurality of proximal optical fibers 5 are set so that the lengths of the plurality of proximal optical fibers 5 are different. Therefore, in the state after the third step, the lengths of the plurality of derived optical fibers 2 are different. This completes the method for manufacturing the optical cable structure.

[0029] As described above, in the optical cable structure and manufacturing method thereof of the first embodiment, the lengths of the multiple outgoing optical fibers 2 outgoing from the end of the sheath S are different. Therefore, the multiple optical connectors 3 provided at the respective tip portions of the multiple outgoing optical fibers 2 can be positioned with a shift in the outgoing direction of the outgoing optical fibers 2. This makes it possible to prevent the multiple optical connectors 3 from becoming bulky in the radial direction of the optical cable C. Therefore, it becomes possible to accommodate the multiple connector-equipped optical fibers 1 in a tubular member 100 having a small diameter dimension.

[0030] In addition, in the optical cable structure and its manufacturing method of the first embodiment, after the optical connector 3 is terminated to the tip portion (first end portion) 6A of the tip side optical fiber 6, the tip side optical fiber 6 can be connected to the base side optical fiber 5. That is, the termination work of the optical connector 3 can be performed before the tip side optical fiber 6 is connected to the base side optical fiber 5. Therefore, even if the lengths of the multiple lead-out optical fibers 2 in the optical cable structure after manufacture are different, the termination work of the optical connector 3 for the multiple lead-out optical fibers 2 accommodated in the tubular member 100 can be easily performed. Specifically, since the positions of the tip portions (first end portions) 6A of the multiple tip side optical fibers 6 can be easily aligned, the termination work (particularly the polishing work and the inspection work) of the optical connector 3 for the tip side optical fiber 6 can be easily performed.

[0031] Moreover, in the optical cable structure and its manufacturing method of the first embodiment, the lengths of the multiple base-side optical fibers 5 extending from the end of the sheath S are different. Therefore, the multiple connection parts 7 provided at the respective tip parts of the multiple base-side optical fibers 5 can be positioned with a shift in the longitudinal direction of the lead-out optical fiber 2. This makes it possible to prevent the multiple connection parts 7 from becoming bulky in the radial direction of the optical cable C. Therefore, it becomes possible to easily accommodate the multiple connectorized optical fibers 1 in the tubular member 100 having a small diameter. In the first embodiment, the diameter of the connector connection part 71 is larger than the diameter of the lead-out optical fiber 2, and therefore the above effect is particularly useful.

[0032] In the optical cable structure and the manufacturing method thereof according to the first embodiment, the length of the plurality of tip side optical fibers 6 is equal. This makes it possible to manufacture the optical cable structure using the plurality of tip side optical fibers 6 having the same length. Therefore, it becomes possible to manufacture the optical cable structure efficiently.

[0033] Moreover, in the optical cable structure and the manufacturing method thereof according to the first embodiment, the base end side optical fiber 5 and the tip end side optical fiber 6 are mechanically connected by the connector connecting portion 71. This makes it possible to easily connect the base end side optical fiber 5 and the tip end side optical fiber 6 without using a device such as a fusion splicer.

[0034] Second Embodiment Next, an optical cable structure and a manufacturing method thereof according to a second embodiment of the present invention will be described with reference to Fig. 9 to Fig. 12. In the following description, configurations common to those already described will be denoted by the same reference numerals, and duplicated description will be omitted.

[0035] 9, the optical cable structure of the second embodiment, like the first embodiment, has a plurality of connectorized optical fibers 1B that are led out from an end of a sheath S of an optical cable C and housed in a tubular member 100. In addition, the led-out optical fiber 2B of each connectorized optical fiber 1B has a connection portion 7B that connects a base end side optical fiber 5 and a tip end side optical fiber 6. The connecting portion 7B of the second embodiment is a fusion splicing portion 71B that fusion splices the base end side optical fiber 5 and the tip end side optical fiber 6. As shown in Fig. 10 and Fig. 11, the fusion splicing portion 71B of the second embodiment is configured separately from the base end side optical fiber 5 and the tip end side optical fiber 6.

[0036] The fusion splice 71B has a base end portion 72B and a tip end portion 73B. The base end portion 72B is composed of a multicore fiber having multiple cores. The cross-sectional shape of the base end portion 72B is similar to the cross-sectional shape of the base end optical fiber 5 shown in FIG. 4. The tip end portion 73B is composed of multiple single-core fibers having one core. The cross-sectional shape of the tip end portion 73B is similar to the cross-sectional shape of the base end side of the tip end optical fiber 6 shown in FIG. 5. The base end portion 72B and the tip end portion 73B are arranged in the longitudinal direction of these cores (the left-right direction in FIG. 10) and joined by fusion or the like. As a result, the multiple cores of the base end portion 72B and the multiple cores of the tip end portion 73B are individually optically coupled to each other. According to this configuration, when connecting an optical connector (e.g., an MT ferrule) to the end of an optical fiber, if the end of the optical fiber located on the optical connector side is a multi-core fiber, alignment work is required in the rotational direction of the optical fiber (direction around the axis of the optical fiber). However, if the end of the optical fiber is a single-core fiber, the optical fiber has no rotational directionality, making the above-mentioned alignment work unnecessary.

[0037] A base end portion 72B of the fusion splice 71B is fusion spliced ​​to the tip end of the base end optical fiber 5. A tip end portion 73B of the fusion splice 71B is fusion spliced ​​to the base end of the tip end optical fiber 6. As a result, the core 52 (see FIG. 4) of the base end optical fiber 5 and the core 62 (see FIG. 5) of the tip end optical fiber 6 are optically coupled via the cores of the fusion splice 71B (base end portion 72B and tip end portion 73B).

[0038] In the second embodiment, the length of the fusion splice 71B is shorter than the lengths of the base end side optical fiber 5 and the tip end side optical fiber 6. In the second embodiment, the lengths of the fusion splice 71B are equal among the multiple output optical fibers 2B. Although not shown, the fusion splice 71B may have, for example, a protective sleeve for protecting the fusion portion between the base end side optical fiber 5 and the tip end side optical fiber 6. In this case, the diameter of the fusion splice 71B is larger than the diameter of the output optical fiber 2.

[0039] Next, a method for manufacturing the optical cable structure according to the second embodiment will be described. The manufacturing method of the second embodiment differs from the manufacturing method of the first embodiment in that in the first step, a tip side connector 73 (see Figures 7 and 8) is not terminated to the tip side optical fiber 6, and further in the second step, a base side connector 72 (see Figures 7 and 8) is not terminated to the base side optical fiber 5. In addition, in the manufacturing method of the second embodiment, the method of connecting the second end portions (base end portions) 6B of the multiple tip side optical fibers 6 to the tip portions of the multiple base end side optical fibers 5 in the third step is different from the manufacturing method of the first embodiment. The third step in the manufacturing method according to the second embodiment will be described below.

[0040] 10 to 12, in the third step of the second embodiment, the tip end of the base end optical fiber 5 and the base end of the tip end optical fiber 6 are fusion spliced ​​by a fusion splice 71B. Specifically, first, as shown in Figs. 11 and 12, the fusion splice 71B is disposed between the tip end of the base end optical fiber 5 and the base end of the tip end optical fiber 6. Then, as shown in Fig. 10, the tip end of the base end optical fiber 5 is fusion spliced ​​to the base end part 72B of the fusion splice 71B. In addition, the base end of the tip end optical fiber 6 is fusion spliced ​​to the tip end part 73B of the fusion splice 71B. After the first and second steps, the third step of the second embodiment is carried out, thereby completing the manufacturing method of the second embodiment.

[0041] According to the second embodiment, the same effects as those of the first embodiment are achieved. Furthermore, according to the second embodiment, the base end side optical fiber 5 and the tip end side optical fiber 6 are fusion spliced ​​together, which allows the base end side optical fiber 5 and the tip end side optical fiber 6 to be spliced ​​together with higher reliability.

[0042] In the second embodiment, the fusion splice 71B is configured separately from the base end side optical fiber 5 and the tip end side optical fiber 6. The fusion splice 71B has a base end side section 72B configured from a multi-core fiber similar to the base end side optical fiber 5, and a tip end side section 73B configured from a plurality of single-core fibers similar to the tip end side optical fiber 6. Therefore, the base end side optical fiber 5 and the tip end side optical fiber 6 can be connected by fusion splicing between multicore fibers and between multiple single-core fibers. Here, fusion splicing between optical fibers of the same type can be performed more easily than fusion splicing between optical fibers of different types (i.e., fusion splicing between a multicore fiber and multiple single-core fibers). This allows the base end side optical fiber 5 and the tip end side optical fiber 6 to be fusion spliced ​​easily.

[0043] Furthermore, a large number of fusion splices 71B having a base end portion 72B and a tip end portion 73B can be manufactured in advance before fusion splicing the base end optical fiber 5 and the tip end optical fiber 6. This makes it possible to efficiently fusion splice a plurality of base end optical fibers 5 and a plurality of tip end optical fibers 6. From the above, it becomes possible to efficiently manufacture the optical cable structure.

[0044] In the second embodiment, for example, the length of the fusion splice portion 71B may be different among the multiple output optical fibers 2 B. For example, the lengths of the multiple output optical fibers 2 B may be made different by making the lengths of the fusion splice portion 71B different among the multiple output optical fibers 2 B.

[0045] In the second embodiment, the length of the fusion splice 71B may be greater than or equal to the lengths of the proximal optical fiber 5 and the distal optical fiber 6, for example.

[0046] In the second embodiment, the fusion splice 71B may be formed, for example, by the tip end of the base end side optical fiber 5 and the base end of the tip end side optical fiber 6. That is, the base end side optical fiber 5 and the tip end side optical fiber 6 may be directly fusion spliced.

[0047] Although the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit and scope of the present invention.

[0048] In the present invention, for example, the lengths of the multiple base end side optical fibers 5 may be equal. In this case, for example, the lengths of the multiple tip end side optical fibers 6 may be made different, thereby making the lengths of the multiple lead-out optical fibers 2, 2B different.

[0049] In the present invention, both the base end side optical fiber 5 and the tip end side optical fiber 6 may be, for example, a multi-core fiber 51, or may be, for example, composed of a plurality of single-core fibers 61. In addition, the base end side optical fiber 5 and the tip end side optical fiber 6 may be one single-core fiber 61.

[0050] In the manufacturing method of the optical cable structure of the present invention, for example, in the first step, the lengths of the multiple distal optical fibers 6 may be set so that the lengths of the multiple distal optical fibers 6 are different. In this case, in the second step, for example, as in the above embodiment, the lengths of the multiple proximal optical fibers 5 may be set so that the lengths of the multiple proximal optical fibers 5 are different, or the lengths of the multiple proximal optical fibers 5 may be set so that the lengths of the multiple proximal optical fibers 5 are equal. By setting the lengths of the multiple distal optical fibers 6 and the multiple proximal optical fibers 5 in this manner, the lengths of the multiple derived optical fibers 2, 2B in the manufactured optical cable structure can also be made different.

[0051] In the present invention, the lengths of all the lead-out optical fibers 2, 2B extending from the end of the sheath S may not be different. For example, among all the lead-out optical fibers 2, 2B extending from the end of the sheath S, some of the lead-out optical fibers 2, 2B may have the same length. For example, the lead-out optical fibers 2, 2B extending from the end of the sheath S may be divided into a plurality of groups, and the lengths of the lead-out optical fibers 2, 2B constituting the same group may be the same, and the lengths of the lead-out optical fibers 2, 2B of different groups may be different. In this case, the optical connectors 3 provided at the tips of the lead-out optical fibers 2, 2B constituting the same group are disposed at the same position in the lead-out direction of the lead-out optical fibers 2, 2B. Moreover, the optical connectors 3 provided at the tips of the lead-out optical fibers 2, 2B of different groups are positioned shifted in the lead-out direction of the lead-out optical fibers 2, 2B. [Explanation of symbols]

[0052] 1, 1B... optical fiber with connector, 2, 2B... derived optical fiber, 3... optical connector, 5... base end side optical fiber, 6... tip end side optical fiber, 7, 7B... connection portion, 51... multi-core fiber, 52... core, 61... single-core fiber, 62... core, 71... connector connection portion, 71B... fusion splice portion, 100... tubular member, C... optical cable, S... sheath

Claims

1. An optical cable structure having a plurality of connectorized optical fibers led out from an end of a sheath of an optical cable and housed in a tubular member having a predetermined length, Each of the plurality of connectorized optical fibers includes an output optical fiber output from an end of the sheath, and an optical connector provided at a tip end of the output optical fiber in a direction in which the output optical fiber is output. The lengths of at least some of the plurality of output optical fibers output from the end of the sheath are different, Each of the plurality of derived optical fibers has a base end side optical fiber located on an end side of the sheath, a tip end side optical fiber located on the optical connector side, and a connection portion that connects the base end side optical fiber and the tip end side optical fiber, When the plurality of connectorized optical fibers are housed in the tubular member, connection portions of the plurality of output optical fibers are located inside the tubular member, The lengths of the plurality of base-end side optical fibers extending from the end of the sheath are different, An optical cable structure in which the plurality of tip-side optical fibers are equal in length.

2. 2. The optical cable structure according to claim 1, wherein the connection portion is a fusion splice portion that fusion-splices the base end side optical fiber and the tip end side optical fiber.

3. 2. The optical cable structure according to claim 1, wherein the connecting portion is a connector connecting portion that mechanically connects the base end side optical fiber and the tip end side optical fiber.

4. the base end side optical fiber is a multi-core fiber having a plurality of cores, the distal end optical fiber is composed of a plurality of single-core fibers each having one core, 3. The optical cable structure according to claim 1, wherein the connection portion optically couples a plurality of cores of the multi-core fiber and a plurality of cores of the single-core fiber individually.

5. A method for manufacturing an optical cable structure having a plurality of connectorized optical fibers led out from an end of a sheath of an optical cable and housed in a tubular member having a predetermined length, comprising the steps of: A first step of terminating an optical connector to a first end portion in a longitudinal direction of the tip side optical fibers having the same length; a second step of leading out a plurality of base end side optical fibers having different lengths from an end of the sheath; and a third step of, after the first step and the second step, connecting second end portions in the longitudinal direction of the plurality of distal end optical fibers to distal ends of the plurality of proximal end optical fibers, respectively, to configure the plurality of connectorized optical fibers having an outflow optical fiber constituted by the proximal end optical fiber and the distal end optical fiber and the optical connector, and extending from an end of the sheath. A method for manufacturing an optical cable structure.

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