Fiber optic cables and fiber optic cable connection systems

Abstract

An optical fiber cable (1) provided with: a plurality of optical fiber core wires (25) in which each optical fiber core wire (25) has a core part (251), a cladding part (252) for covering the outer periphery of the core part (251), and coating parts (254, 255) for covering the outer periphery of the cladding part (252); and a cable sheath (23) in which the plurality of optical fiber core wires (25) are accommodated, a multicore connector (3) capable of connecting a plurality of 24 or more optical fiber core wires (25) being provided at one end of the plurality of optical fiber core wires (25), and the density of the plurality of optical fiber core wires (25) in the optical fiber cable being 6.5 cores / mm2 to 9.0 cores / mm2.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to fiber optic cables and fiber optic cable connection systems. [Background technology]

[0002] Patent Document 1 discloses a multi-core optical fiber cable in which a plurality of optical fiber ribbons are assembled and integrated at high density. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2004-161499 Summary of the Invention [Means for solving the problem]

[0004] An optical fiber cable according to one aspect of the present disclosure includes: a plurality of optical fiber cores, each having a core portion, a clad portion covering the outer periphery of the core portion, and a coating portion covering the outer periphery of the clad portion; a cable jacket that accommodates the plurality of optical fiber cores; Equipped with , laid by air pressure feeding 1. A fiber optic cable comprising: a multi-fiber connector capable of connecting 24 or more of the optical fiber core wires to one end of the optical fiber core wires; The density of the optical fiber core wires in the optical fiber cable is 6.5 cores / mm 2 More than 9.0 cores / mm 2 Below is the law of nature, The cable jacket contains 1728 or more of the optical fiber core wires, and the optical fiber core wires have an outer diameter of less than 200 μm. The fluctuation range of the outer diameter of the cladding portion is ±0.5 μm or less, a metal protective tube for accommodating the multi-fiber connector is provided at the tip of the optical fiber cable; The tip of the protective tube is rounded, The outer diameter of the protective tube is equal to or less than the outer diameter of the optical fiber cable excluding the protective tube + 2 mm. .

[0005] An optical fiber cable connection system according to one aspect of the present disclosure includes: An optical fiber cable connection system for connecting the above optical fiber cable with an indoor optical fiber cable having a multi-fiber connector of 24 or more fibers at one end, The connection portion between the optical fiber cable and the indoor optical fiber cable is covered by a connection box. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram illustrating an optical fiber cable according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a cross-sectional view of an optical fiber core. [Figure 4] FIG. 4 is a diagram illustrating a multi-fiber connector for an optical fiber cable. [Figure 5] FIG. 5 is a cross-sectional view of a cable main body of an optical fiber cable according to the second embodiment. [Figure 6] FIG. 6 is a schematic diagram illustrating an optical fiber cable connection system. DETAILED DESCRIPTION OF THE INVENTION

[0007] (Problem to be solved by this disclosure) Optical fiber cables such as ultra-high-core cables are traditionally laid by pulling, and then spliced ​​to indoor cables by fusion splicing. However, the pulling and fusion splicing methods require time-consuming tasks such as winding the optical fiber cable into a figure-eight shape, and the splicing process takes a long time, which is problematic. One idea for shortening the laying time is to lay the cable by air pressure feeding, but there is still room for further improvement in order to air pressure feed a multi-core cable and shorten the time required for splicing work.

[0008] (Effects of the present disclosure) An object of the present disclosure is to provide a multi-fiber optical fiber cable with improved installation ease.

[0009] (Description of Embodiments of the Present Disclosure) First, embodiments of the present disclosure will be listed and described. An optical fiber cable according to one aspect of the present disclosure includes: (1) A plurality of optical fiber cores, each having a core portion, a clad portion covering the outer periphery of the core portion, and a coating portion covering the outer periphery of the clad portion; a cable jacket that accommodates the plurality of optical fiber cores; Equipped with , laid by air pressure feeding 1. A fiber optic cable comprising: A multi-core connector is provided at one end of the plurality of optical fiber cores, and the plurality of optical fiber cores connected to one connector have 24 or more cores, The density of the optical fiber core wires in the optical fiber cable is 6.5 cores / mm 2 More than 9.0 cores / mm 2 Below is the law of nature, The cable jacket contains 1728 or more of the optical fiber core wires, and the optical fiber core wires have an outer diameter of less than 200 μm. The fluctuation range of the outer diameter of the cladding portion is ±0.5 μm or less, a metal protective tube for accommodating the multi-fiber connector is provided at the tip of the optical fiber cable; The tip of the protective tube is rounded, The outer diameter of the protective tube is equal to or less than the outer diameter of the optical fiber cable excluding the protective tube + 2 mm. . By providing the optical fiber cable with a high density of optical fiber cores as described above, the optical fiber cable can be made thinner. This allows the optical fiber cable to be made lighter, making it easier to install by air pressure feeding. Furthermore, since the connectors are pre-installed, fusion splicing is not required, thereby shortening the splicing work time. Furthermore, optical fiber cables containing 1,728 or more optical fiber cores, so-called ultra-high-core cables, can also be installed by air pumping. By making the outer diameter of the optical fiber core less than 200 μm, it becomes easy to make the optical fiber cable thinner. Since the outer diameter of the cladding is manufactured so that it varies within a certain range, the transmission loss that occurs when optical fiber cables are connected together using a multi-core connector can be reduced. Even if a protective tube is provided at the tip of the multi-core connector, the diameter of the entire optical fiber cable can be made sufficiently thin.

[0013] (5) Silicone may be added to the cable jacket. In the optical fiber cable having the above configuration, the addition of silicone to the cable jacket reduces the coefficient of friction of the cable jacket against the air-pumping duct, thereby enabling the optical fiber cable to be air-pumped for a long distance during installation.

[0014] (6) Inside the cable jacket, the plurality of optical fiber cores are bundled into a plurality of subunits, The outer peripheries of the plurality of sub-units may be covered with a sub-unit covering portion containing a flame retardant material. According to the optical fiber cable having the above-described configuration, each of the subunit coatings formed inside the optical fiber cable contains a flame-retardant material. This makes it possible to extract the optical fiber core from the outdoor cable in subunit units and lay it on each floor, even in cases where higher flame retardancy is required, such as in indoor wiring within a building. This makes it easier to handle the optical fiber cable when laying it.

[0015] (7) The thickness of the coating of the subunit coating portion may be 0.05 mm or more and 0.5 mm or less. If the coating thickness of the subunit coating portion is too thin, the optical fiber core wire inside cannot be effectively protected, and if the coating thickness of the subunit coating portion is too thick, the thin diameter of the entire optical fiber cable required for air pressure feeding cannot be achieved.However, if the coating thickness of the subunit coating portion is as described above, it is possible to achieve both protection of the optical fiber core wire and a thin diameter of the entire optical fiber cable.

[0016] (8) The coatings of the optical fibers forming the subunit may contain a flame-retardant material. According to the optical fiber cable having the above configuration, the coating of the optical fiber core wire inside the subunit coating also contains a flame-retardant material, so that the flame resistance of the entire optical fiber cable is improved.

[0018] (10) The number of cores of the plurality of optical fibers that can be connected to the multi-core connector may be 96 or more. According to the optical fiber cable having the above configuration, by increasing the number of optical fiber cores that can be connected to a multi-core connector, the number of multi-core connectors required is reduced, thereby achieving a reduction in the diameter of the entire optical fiber cable.

[0019] An optical fiber cable connection system according to one aspect of the present disclosure includes: (11) An optical fiber cable connection system for connecting the optical fiber cable according to any one of (1) to (10) above with an indoor optical fiber cable having a multi-fiber connector of 24 or more fibers at one end, The connection portion between the optical fiber cable and the indoor optical fiber cable is covered by a connection box. The optical fiber cable connection system configured as above allows the optical fiber cable pulled in from outdoors to be easily connected to the indoor optical fiber cable using the multi-fiber connector. In addition, the connection part is covered by the connection box, making it easy to effectively protect the connection part.

[0020] (Details of the embodiments of the present disclosure) Specific examples of optical fiber cables according to embodiments of the present disclosure will be described below with reference to the drawings. It should be noted that the present disclosure is not limited to these examples, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0021] (First embodiment) An optical fiber cable 1 according to a first embodiment will be described with reference to FIG. Fig. 1 is a diagram illustrating an optical fiber cable 1 according to a first embodiment. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. As shown in Fig. 1, the optical fiber cable 1 includes a cable main body 2 and a multi-fiber connector 3. The optical fiber cable 1 according to this embodiment is an optical fiber cable that is laid by air pressure feeding.

[0022] The multi-fiber connector 3 is, for example, a connector based on an MT connector. For convenience of illustration, only three multi-fiber connectors 3 are shown in Fig. 1, but the number of multi-fiber connectors 3 may be determined appropriately depending on the number of optical fiber cores 25 accommodated in the optical fiber cable 1. The multi-fiber connector 3 is configured so that at least 24 or more optical fiber cores 25 can be connected to one multi-fiber connector 3. The multi-fiber connector 3 has, for example, a plurality of ferrules 31 therein. The ferrules 31 are, for example, MT ferrules configured so that the tips of the multiple optical fiber cores 25 are inserted and fixed therein.

[0023] 2, the cable main body 2 includes a slotted rod 21, a holding winding tape 22, a cable jacket 23, and a tensile member 24. The slotted rod 21 has a plurality of slotted grooves. The slotted grooves are twisted in a spiral or SZ shape relative to the longitudinal direction of the cable main body 2.

[0024] Each slot accommodates a plurality of optical fiber core wires 25 that have been rolled from a parallel state into a densely packed state. The optical fiber core wires 25 may be accommodated in the slot as an optical fiber ribbon configured by connecting a plurality of optical fiber core wires 25 in parallel in a direction perpendicular to the longitudinal direction.

[0025] A pressure winding tape 22 is wound around the slot rod 21. The pressure winding tape 22 is wound longitudinally or spirally around the entire slot rod 21 and the optical fiber 25. The pressure winding tape 22 is made water-absorbent by adhering water-absorbent powder to a base fabric made of polyester or the like. Note that although the cable main body 2 according to this embodiment includes the pressure winding tape 22, the cable main body 2 does not necessarily have to include the pressure winding tape 22.

[0026] The cable sheath 23 covers the periphery of the pressure winding tape 22. In other words, the pressure winding tape 22 and the optical fiber 25 are housed in the space inside the cable sheath 23. When the diameter of the cable main body 2 is 22 mm, the thickness of the cable sheath 23 is preferably 1.5 mm.

[0027] As described above, the optical fiber core wires 25 are housed in the space inside the cable jacket 23. At this time, the density of the housed optical fiber core wires 25 is 6.5 cores / mm 2 More than 9.0 cores / mm 2 The density of the optical fiber core wires 25 is 6.5 cores / mm 2 In this case, the proportion of the area occupied by the optical fiber 25 in the optical fiber cable 1 increases. The density of the optical fiber 25 is the value obtained by dividing the number of optical fiber 25 housed in the optical fiber cable 1 by the cross-sectional area of ​​the cable (the cross-sectional area determined from the diameter of the cable main body 2).

[0028] In addition, even when accommodating the same number of optical fiber cores (25), the 2 6.5 fibers / mm compared to: 2 In the above case, the optical fiber core 25 can be accommodated in a smaller space, which enables a reduction in the diameter of the optical fiber cable 1. Furthermore, the reduction in diameter allows a reduction in the volume of the slotted rod 21 and the cable jacket 23 provided around the slotted rod 21, which also reduces the weight of the entire optical fiber cable 1.

[0029] If the density at which the optical fiber core wires 25 are housed becomes too high, the transmission loss of the entire optical fiber cable 1 may increase. Therefore, the density of the housed optical fiber core wires 25 is set to 9.0 cores / mm 2 It is desirable that the following:

[0030] In this embodiment, by providing the optical fiber cores 25 at a high density as described above, the optical fiber cable 1 can be made thinner and lighter in weight. This makes it easier to lay the optical fiber cable 1 by air pressure feeding. Furthermore, since the connectors are provided in advance, no fusion splicing work is required when connecting the optical fiber cables 1 together, thereby reducing the time required for the connecting work.

[0031] In the cable main body 2, the number of optical fiber cores 25 housed inside the cable jacket 23 may be 1728 or more. Even in the case of a so-called ultra-high-core cable having a large number of optical fiber cores 25 inside, such as the optical fiber cable 1 according to the present embodiment, by configuring it as described above, it becomes possible to lay the cable by air feeding.

[0032] Next, the optical fiber 25 housed inside the slot groove will be described. FIG. 3 is a cross-sectional view of the optical fiber 25. As shown in FIG. 3, the optical fiber 25 has a glass fiber 253 composed of a core 251 having a refractive index higher than that of the surrounding glass and a cladding 252 surrounding the core 251, two coating layers 254 and 255 covering the glass fiber 253, and a colored layer 256 covering the coating layer 255. Of the two coating layers 254 and 255, the inner coating layer 254 is formed from a cured product of a primary resin. Furthermore, of the two coating layers 254 and 255, the outer coating layer 255 is formed from a cured product of a secondary resin.

[0033] The glass fiber 253 has a core 251 at its center, and a cladding 252 that surrounds the core 251 .

[0034] The primary resin constituting the inner primary coating portion in contact with the glass fiber 253 is a soft resin with a relatively low Young's modulus that serves as a buffer layer. The secondary resin constituting the outer secondary coating portion is a hard resin with a higher Young's modulus than the primary resin that serves as a protective layer. The Young's modulus of the cured primary resin at room temperature (e.g., 23°C) is 1.0 MPa or less, and preferably 0.7 MPa or less. The Young's modulus of the cured secondary resin at room temperature (e.g., 23°C) is 900 MPa or more, preferably 1000 MPa or more, and more preferably 1500 MPa or more.

[0035] Here, it is desirable that the diameter D1 of the coated optical fiber 25 is less than 200 μm. By determining the diameter D1 of the coated optical fiber 25 as described above, it becomes easy to make the optical fiber cable 1 thinner.

[0036] Furthermore, it is desirable that the fluctuation range of the outer diameter D2 of the cladding portion 252 be within a certain range when manufactured. Specifically, it is desirable that the fluctuation range of the outer diameter D2 of the cladding portion 252 be ±0.5 μm or less. By manufacturing the cladding portion 252 as described above, the fluctuation range of the outer diameter D2 of the cladding portion 252 is manufactured to fall within a certain range, thereby reducing the transmission loss that occurs when optical fiber cables 1 are connected together using the multi-fiber connector 3.

[0037] Furthermore, in the optical fiber cable 1 according to this embodiment, silicone may be added to the cable jacket 23. This reduces the coefficient of friction of the cable jacket 23 with respect to the air-pressure-feeding duct 50. This reduces the frictional force that occurs when the cable jacket 23 rubs against the air-pressure-feeding duct 50 (see FIG. 4), thereby realizing an optical fiber cable 1 that can be air-pressurized for a long distance during installation.

[0038] In the optical fiber cable 1 according to this embodiment, it is desirable that the number of cores in the optical fiber 25 that can be connected to the multi-core connector 3 is 96 or more. As the number of cores in the optical fiber 25 that can be connected to the multi-core connector 3 increases, the number of multi-core connectors 3 required decreases, making it easier to connect the optical fiber cables 1.

[0039] Returning to FIG. 1, the optical fiber cable 1 according to this embodiment further includes a protective tube 4. The protective tube 4 is, for example, a metal member. The protective tube 4 is provided at the end of the optical fiber cable 1 and houses the multi-fiber connector 3 therein. The protective tube 4 protects the end of the cable main body 2 and the multi-fiber connector 3 from damage during air pressure feeding.

[0040] 1, the outer diameter D3 of the protective tube 4 is slightly larger than the outer diameter of the optical fiber cable 1 excluding the protective tube 4. In the optical fiber cable 1 according to this embodiment, the "outer diameter of the optical fiber cable 1 excluding the protective tube 4" corresponds to the outer diameter D4 of the cable main body 2. It is preferable that the outer diameter D3 of the protective tube 4 is larger than the outer diameter D4 of the cable main body 2 and smaller than the outer diameter D4 + 2 mm.

[0041] In this way, in the optical fiber cable 1 according to this embodiment, the size of the outer diameter D3 of the protective tube 4 is kept within a certain range that is larger than the outer diameter of the optical fiber cable 1 excluding the protective tube 4. This allows the entire optical fiber cable 1 to be made sufficiently thin in diameter even when the protective tube 4 is provided to protect the multi-fiber connector 3 and the like.

[0042] Next, a description will be given of the multi-fiber connector 3 of the optical fiber cable 1. Fig. 4 is a diagram illustrating the multi-fiber connector 3 of the optical fiber cable 1. A case where a protective tube 4 is provided at the tip of the optical fiber cable 1 will be described with reference to Fig. 4.

[0043] During installation, the optical fiber cable 1 is inserted through the compressed air duct 50. The inner diameter of the compressed air duct 50 is, for example, 28 mm. The outer diameter of the cable main body 2 is approximately 1 mm smaller than the outer diameter of the protective tube 4. For example, in the optical fiber cable 1 of this embodiment, the outer diameter of the cable main body 2 is 22 mm, and the outer diameter of the protective tube 4 is 23 mm. A multi-core connector 3 is provided inside the protective tube 4. A plurality of coated optical fibers are connected to the multi-core connector 3. It is desirable that the outer diameter of the multi-core connector 3 is approximately half the inner diameter of the protective tube 4. For example, the inner diameter of the protective tube 4 is 19 mm, and the outer diameter of the multi-core connector is 10 mm. By making the multi-core connector 3 approximately half the size of the inner diameter of the protective tube 4 in this way, it is possible to ensure space for passing coated optical fibers 25 to be connected to another multi-core connector 3.

[0044] When the multiple multi-core connectors 3 provided inside the protective tube 4 are approximately half the size of the inner diameter of the protective tube 4, the multiple multi-core connectors 3 can be arranged staggered in the longitudinal direction of the optical fiber cable 1, as shown in Figure 4, thereby preventing the inner diameter of the protective tube 4 from becoming too large.

[0045] Second Embodiment Next, an optical fiber cable 1A according to a second embodiment will be described. For the sake of convenience, the description of the members having the same reference numerals as those already described in the second embodiment will be omitted.

[0046] 5 is a cross-sectional view of a cable main body 2A of an optical fiber cable 1A according to the second embodiment. As with the first embodiment, the optical fiber cable 1A according to the second embodiment includes a cable main body 2A and a multi-fiber connector 3 (see FIGS. 1 and 4) that is common to the first embodiment. However, compared to the first embodiment, the internal structure of the cable main body 2A is different. More specifically, no slot rod 21 is provided in the space inside the cable jacket, and multiple optical fiber cores 25 are bundled together into multiple subunits 250.

[0047] Each subunit 250 is covered by a subunit covering portion 250a. By tearing the cable jacket 23, each subunit 250 covered by the subunit covering portion 250a can be wired. The subunit covering portion 250a is formed to include a flame-retardant material. An example of the subunit covering portion 250a formed to include a flame-retardant material is covering the subunit 250 with flame-retardant polyolefin.

[0048] Generally, optical fiber cables used indoors require higher flame retardancy than those used outdoors. For this reason, optical fiber cables with different flame retardancy are used for indoor and outdoor use. Normally, when an outdoor optical fiber cable with low flame retardancy is brought indoors, it is necessary to connect it to an indoor cable with high flame retardancy before bringing it indoors.

[0049] The optical fiber cable 1A according to this embodiment is configured so that each of the multiple subunit sheaths 250a formed therein contains a flame-retardant material. This makes it possible to extract the optical fiber core wires 25 from the outdoor cable for each subunit 250 and lay them on each floor, even in cases where higher flame retardancy is required, such as for wiring inside a building. This makes it easier to handle the optical fiber cable 1A when laying it.

[0050] The coating thickness of the subunit coating portion 250a is preferably 0.05 mm or more and 0.5 mm or less. If the coating thickness of the subunit coating portion 250a is too thin, the internal optical fiber core wire cannot be effectively protected, and if the coating thickness of the subunit coating portion 250a is too thick, the overall diameter of the optical fiber cable 1A, which is necessary for air pumping, cannot be reduced. With the coating thickness of the subunit coating portion 250a as described above, it is possible to protect the optical fiber core wire 25 and reduce the overall diameter of the optical fiber cable 1A.

[0051] Furthermore, it is desirable that the coatings 254, 255 of the multiple optical fibers 25 constituting the subunit 250 contain a flame-retardant material. Not only the subunit coating 250a but also the coatings 254, 255 of the optical fibers 25 therein contain a flame-retardant material, which improves the flame resistance of the entire optical fiber cable 1A.

[0052] Next, an optical fiber cable connection system 100 using the optical fiber cables 1, 1A according to the first and second embodiments will be described. Fig. 6 is a schematic diagram illustrating the optical fiber cable connection system 100. As shown in Fig. 6, the optical fiber cable connection system 100 includes an optical fiber cable 1 according to the first embodiment that is pulled into a building H from outside the building H, and an indoor optical fiber cable 101. The indoor optical fiber cable 101 includes a multi-fiber connector (not shown) with 24 or more fibers at at least one end thereof. The optical fiber cable 1 and the indoor optical fiber cable 101 can be connected by the multi-fiber connector 3 included in the optical fiber cable 1 and the multi-fiber connector included in the indoor optical fiber cable 101. The optical fiber cable pulled into the building H from outside may be the optical fiber cable 1A according to the second embodiment. In the case of the optical fiber cable 1A, the subunit 250 may be wired as an indoor optical fiber cable 101 without going through the junction box 102.

[0053] The optical fiber cable 1 and the indoor optical fiber cable 101 are connected inside the connection box 102. In other words, the connection portion between the optical fiber cable 1 and the indoor optical fiber cable 101 is covered by the connection box 102.

[0054] The optical fiber cable 1 includes the multi-fiber connector 3, so that it can be easily connected to the indoor optical fiber cable 101. Furthermore, the connection portion is covered by the connection box 102, so that the connection portion can be easily protected effectively.

[0055] Although the present disclosure has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present disclosure. Furthermore, the number, position, shape, etc. of the components described above are not limited to the above embodiments, and can be changed to the number, position, shape, etc. that are suitable for implementing the present disclosure. [Explanation of symbols]

[0056] 1,1A fiber optic cable 2,2A Cable body 3 Multi-fiber connector 4 Protection tube 21 Slot Rod 22 Tape 23 Cable jacket 24 Tensile strength body 25 optical fiber core 31 Ferrule 50 Air pressure duct 100 Fiber Optic Cable Connection System 101 Indoor fiber optic cable 102 Junction box 250 subunits 250a Subunit coating 251 Core 252 Cladding 253 Glass Fiber 254 Covering part 255 Covering part 256 Colored layer

Claims

1. a plurality of optical fiber cores, each having a core portion, a clad portion covering the outer periphery of the core portion, and a coating portion covering the outer periphery of the clad portion; a cable jacket that accommodates the plurality of optical fiber cores; An optical fiber cable that is laid by air pressure feeding, comprising: a multi-fiber connector is provided at one end of the plurality of optical fiber cores, and the plurality of optical fiber cores to be connected to one connector are 24 or more cores; The density of the optical fiber core wires in the optical fiber cable is 6.5 cores / mm ２ Above, 9.0 cores / mm ２ is as follows: The cable jacket contains 1728 or more optical fiber cores, and the optical fiber cores have an outer diameter of less than 200 μm. The fluctuation range of the outer diameter of the cladding portion is ±0.5 μm or less, a metal protective tube for accommodating the multi-fiber connector is provided at the tip of the optical fiber cable; The tip of the protective tube is rounded, The outer diameter of the protective tube is equal to or less than the outer diameter of the optical fiber cable excluding the protective tube + 2 mm. Fiber optic cable.

2. The cable jacket is silicone-added.

2. The optical fiber cable according to claim 1.

3. The plurality of optical fiber cores are bundled into a plurality of subunits inside the cable jacket, The outer peripheries of the plurality of subunits are covered with a subunit covering portion containing a flame retardant material.

3. The optical fiber cable according to claim 1 or 2.

4. The coating thickness of the subunit coating portion is 0.05 mm or more and 0.5 mm or less. The optical fiber cable according to claim 3.

5. 5. The optical fiber cable according to claim 3, wherein the coatings of the optical fibers forming the subunit contain a flame-retardant material.

6. 6. The optical fiber cable according to claim 1, wherein the number of core fibers of the plurality of optical fibers that can be connected to the multi-core connector is 96 or more.

7. An optical fiber cable connection system for connecting the optical fiber cable according to any one of claims 1 to 6 with an indoor optical fiber cable having a multi-fiber connector of 24 or more fibers at one end, An optical fiber cable connection system, wherein the connection portion between the optical fiber cable and the indoor optical fiber cable is covered by a connection box.

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