JP4774337B2 - Multi-fiber cable - Google Patents

Description

  The present invention provides a single-core coated optical fiber having a coating on the outer periphery of an optical fiber having a characteristic that optical loss does not increase with respect to bending, for example, a photonic crystal fiber having a large number of holes near the center. The present invention relates to an assembled multi-core optical fiber cable.

  Currently, in order to provide diverse and broadband multimedia services, optical fibers having the characteristics of low loss and broadband have been introduced into communication networks. When an optical fiber is used in a communication network, the optical fibers are bundled and coated to provide an optical fiber cable. Up to now, when designing optical fiber cables, (1) without increasing the loss of the optical fiber against external forces such as tension and bending applied to the optical fiber during cable manufacturing, laying and long-term use (2) It was important to ensure long-term reliability. That is, the selection of a structure in which an external force such as tension and bending is not applied to the optical fiber as much as possible has been an important issue. In particular, a design that does not cause an increase in optical loss due to bending of the optical fiber is important (see, for example, Non-Patent Document 1).

  FIG. 9 is a cross-sectional view showing an example of a 100-core optical fiber cable mounted with a 4-core optical fiber tape that is currently widely used. As shown in FIG. 9, a groove (slot) 92 is provided on the outer periphery of the plastic rod 91, and a plurality of single-core, four-core or eight-core optical fiber tapes 93 are mounted while providing a gap portion in one slot 92, The outer cover 94 is provided. Reference numeral 95 denotes a tensile strength body. The optical fiber is protected from external force by the plastic rod 91 and the tensile body 95 so that a large force is not applied to the optical fiber as much as possible. The optical fiber tape is a tape in which a plurality of optical fibers are arranged in a straight line and collectively covered. Usually, a four-core optical fiber tape or an eight-core optical fiber tape in which four or eight optical fibers are collectively coated is used (see, for example, Patent Document 1).

  A communication network is constructed using such an optical fiber cable. However, as demand for optical fibers increases, underground pipes and pipes in buildings are insufficient, and multiple pipes or pipes are provided in one pipe or pipe. An optical fiber cable may be installed. In this case, depending on the diameter of the optical fiber cable previously laid, the gaps in the pipes and pipes are so small that the desired optical fiber cable cannot be laid, increasing the pipes and pipes, resulting in increased costs. An optical fiber cable having a smaller diameter and higher density is desired.

  On the other hand, in recent years, research and development related to optical fibers have greatly advanced, and various optical fiber structures and optical fiber systems have been proposed in order to transmit large volumes of data at high speed.

17A is a schematic diagram illustrating an example of a refractive index profile of a conventional optical fiber, and FIGS. 17B and 17C are schematic diagrams illustrating an example of a refractive index profile of a low bending loss optical fiber. . Center from the outer peripheral (cladding) shown in FIG. 17 (a) In the optical fiber refractive index of the (core) is made delta ₁ higher. On the other hand, as shown in FIG. 17B, the refractive index Δ ₂ (Δ ₂ > Δ ₁ ) of the optical fiber center (core) is further increased, or as shown in FIG. parts by lowering the refractive index delta ₃ of (core) from the outer periphery (cladding), an optical fiber for guiding confine light to the optical fiber center (core) has been proposed (e.g., see non-Patent Document 3.) .

  FIGS. 10A and 10B are schematic cross-sectional views showing a photonic crystal fiber. As shown in FIGS. 10A and 10B, a large number of holes are provided near the center of an optical fiber made of glass, and the refractive index is equivalently lowered from the center of the optical fiber so that An optical fiber called a photonic crystal fiber or a hole assist fiber for confining and guiding light has been proposed (see, for example, Non-Patent Document 2). These optical fibers can greatly suppress an increase in optical loss when the optical fiber is bent, and have a great feature different from the conventional optical fibers.

FIG. 11 is a characteristic diagram showing a comparison of characteristics of increasing optical loss due to bending of a conventional optical fiber and a photonic crystal fiber. As shown in FIG. 11, the optical loss increase characteristics due to bending of a conventional optical fiber and a photonic crystal optical fiber having six holes in the center of the optical fiber are compared. Thus, it can be seen that the effect of confining light is increased by providing a hole in the center of the optical fiber, and the optical loss does not increase even if the optical fiber is bent to a bending radius of 15 mm.

JP-A-62-204214 [Online], June 1, 2005 search, Internet <URL: http: //www.corningcablesystems.com/web/library/litindex.nsf/$ALL/EVO-188-EN/$FILE/EVO-188 -EN.pdf> Takeshi Zhou et al. “Examination of application of photonic crystal fiber to home and building wiring” The Institute of Electronics, Information and Communication Engineers IEICE Technical Report, January 2003, p. 41-46 [Online], search on April 27, 2006, Internet <URL: http: //www.sei.co.jp/tr/t_technical_pdf/sei10358.pdf>

  In order to be able to lay a plurality of optical fiber cables in one pipe line or pipe, an optical fiber cable that is as thin as possible is desired. In particular, when a new optical fiber cable is to be installed in a pipeline or pipe in which an optical fiber cable has already been installed, there is a problem that there is no gap and a desired optical fiber cable cannot be installed. Yes. For this reason, an optical fiber cable with a smaller diameter and higher density is required.

  The present invention has been made in view of the above circumstances, and in order to reduce the optical loss caused by an external force applied to the optical fiber cable by using an optical fiber having a characteristic that the optical loss does not increase with respect to bending. By removing inclusions such as plastic rods and tensile bodies that have been used, and by densely accommodating optical fibers, the fibers are gathered together in a high density, and the optical fiber core density in the optical fiber cable is increased as much as possible. An object of the present invention is to provide a multi-core optical fiber cable having a small diameter, light weight and low optical loss.

  In order to obtain an optical fiber having a characteristic that the optical loss does not increase with respect to bending, for example, an optical fiber having an optical loss increase of 0.2 dB / 10 turn or less even when bent at a radius of 15 mm, a photonic such as a holey fiber is used. There are two types of methods: using a crystal fiber and adding a dopant such as GeO to the optical fiber or reducing the core diameter. These two methods can be performed simultaneously.

To accomplish the above object, photonic a multi-fiber optical fiber cable with a set of single-core coated optical fibers subjected to coating the outer periphery of the crystal fiber, the single-core coated optical fiber a plurality of the peripheral A discriminating yarn or tape is wound on the outer circumference which is closely gathered straight or twisted with the surfaces in contact with each other, and a plurality of optical fiber bundles wound with the discriminating yarn or tape are brought into contact with each other. The outer periphery is tightly gathered in a twisted state and is coated with an outer sheath, and the optical fiber is configured so that an increase in optical loss is 0.2 dB / 10 turn or less even when bent at a radius of 15 mm. To do.

The present invention is also a multi-core optical fiber cable in which single-core coated optical fibers coated on the outer periphery of a photonic crystal fiber are gathered, and a plurality of the single-core coated optical fibers are brought into contact with each other at their peripheral surfaces. The first identification yarn or tape is wound around the outer periphery that is closely gathered straight or twisted in a state, and a plurality of optical fiber bundles wound with the first identification yarn or tape are brought into contact with each other. The second identification yarn or tape is wound around the outer periphery that is twisted and densely gathered in a state, and a plurality of optical fiber bundles wound with the second identification yarn or tape are brought into contact with each other. the jacket applied on the outer periphery which closely by assembling twisted state, and the optical fiber, especially that also optical loss increases by bending at radius 15mm is configured to be 0.2dB / 10turn less It is an.

  The present invention is also the multi-core optical fiber cable, wherein the two strength members are embedded in the jacket so as to be symmetrical with each other with respect to the center of the multi-fiber optical fiber cable. The tear cord is embedded in the jacket so as to be symmetrical with each other with respect to the center of the multi-fiber optical fiber cable, and the thickness of the jacket of the tear cord embedding portion is the portion of the portion other than the tear cord embedding portion. It is characterized by being thicker than the thickness of the jacket.

The present invention also provides a multi-core optical fiber cable in which single-core coated optical fibers coated on the outer periphery of the optical fiber are assembled, and a plurality of the single-core coated optical fibers are in contact with each other on their peripheral surfaces. in densely assembled outer periphery to fit a straight or twisted winding the identification yarn or tape, densely twined with further state that said contacting with one another the plurality of the peripheral surface of the optical fiber bundle wound with identification yarn or tape the jacket applied on the outer periphery which is set, and the optical fiber, characterized in that also optical loss increases by bending at radius 15mm by the addition or control of the core diameter of the dopant is configured to be 0.2dB / 10turn less It is what.

The present invention also provides a multi-core optical fiber cable in which single-core coated optical fibers coated on the outer periphery of the optical fiber are assembled, and a plurality of the single-core coated optical fibers are in contact with each other on their peripheral surfaces. In a state where a first identification yarn or tape is wound around an outer circumference that is closely gathered straight or twisted, and a plurality of optical fiber bundles wound with the first identification yarn or tape are in contact with each other. In a state where the second identification yarn or tape is wound around the outer periphery densely gathered by twisting, and a plurality of optical fiber bundles wound with the second identification yarn or tape are in contact with each other. the jacket applied on the outer periphery which closely by assembling twisted, and the optical fiber, also optical loss increases by bending at radius 15mm by the addition or control of the core diameter of the dopants 0.2dB / 10turn less By being configured such that is characterized in.

  The present invention is also the multi-core optical fiber cable, wherein the two strength members are embedded in the jacket so as to be symmetrical with each other with respect to the center of the multi-fiber optical fiber cable. The tear string is embedded in the jacket so as to be symmetric with respect to the center of the multi-core optical fiber cable, and the thickness of the jacket of the embedded portion of the strength member is the thickness of the portion other than the embedded portion of the strength body. It is characterized by being thicker than the thickness of the jacket.

  According to the present invention, in the multi-fiber optical fiber cable, tensile strength fibers are arranged on the outer periphery of the cable core.

The present invention makes use of the feature that the optical loss is not increased with respect to bending by the low bending loss optical fiber and the photonic crystal fiber, and the optical fiber cable has a small diameter, high density, and light weight by densely mounting the optical fiber. Is realized. Specifically, it is sufficient to design in consideration of ensuring long-term reliability.Except for plastic rods, tensile bodies, etc. that have been used to reduce optical loss caused by external forces applied to cables, It is characterized in that the optical fibers are densely accommodated by eliminating problems and gathered at a higher density than conventional optical fiber cables, and the optical fiber core density in the optical fiber cables is increased as much as possible. An optical fiber cable. With this structure, the core density can be set to, for example, 2.5 cores / mm ² or more.

The multi-core optical fiber cable of the present invention makes it possible to omit plastic rods and strength members, and has a small diameter, high density, light weight, low optical loss, and in particular, an optical fiber cable that is easy to design with extremely low optical loss increase. As a result, it is possible to effectively use the accommodation space of the existing pipeline, and at the time of laying a new optical line, the cost for civil engineering equipment investment can be greatly reduced and the construction period can be greatly shortened. Further, since the diameter is smaller than that of the existing optical fiber cable, it is expected that the cable handling performance is improved, the burden on the cable laying operator is reduced, and the cable laying can be performed more quickly. In addition, the fiber receives external force at the time of branching by accommodating the core wires at a high density, but because of the use of an optical fiber having a characteristic that optical loss does not increase with respect to bending, it branches with low loss. be able to. In addition, in the case of obstacle relocation work, etc., the influence on the optical fiber core wire during service can also be reduced. Also, when negotiating between utility poles, the cable is thin and lightweight, so the tension due to the weight of the cable is reduced, the long-term reliability of the cable is improved, and the aerial distance can be extended. With the multi-core optical fiber cable of the present invention, the core density can be set to, for example, 2.5 cores / mm ² or more.

Embodiments of the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing a multi-core optical fiber cable according to a first embodiment of the present invention, and FIG. 2 is a schematic diagram for explaining an optical fiber twisting method according to the first embodiment of the present invention. FIG. 3 and FIG. 3 are schematic views for explaining an optical fiber bundle twisting method according to the first embodiment of the present invention. As shown in FIG. 1, a plurality of, for example, four single-core coated optical fibers 11 that are coated concentrically on the outer periphery of a photonic crystal fiber having a large number of holes near the center are straightened or twisted. An identification yarn or identification tape 12 is wound around the densely gathered outer periphery to form an optical fiber bundle, and a plurality of, for example, seven optical fiber bundles wound with the identification yarn or identification tape 12 are straight or twisted together. A multi-core optical fiber cable 10 is formed by presser winding / jacket 13 on the outer periphery that is densely gathered. FIG. 2 shows an optical fiber twisting method, in which four single-coated optical fibers 11 coated with a photonic crystal fiber are twisted together to form an optical fiber bundle by winding an identification yarn 12 around a densely gathered outer periphery. To do. FIG. 3 shows a method for twisting optical fiber bundles, in which four single-core coated optical fibers 11 are twisted and densely assembled, and seven optical fiber bundles are twisted and closely gathered. In addition, a buffer layer 14 such as yarn or resin can be provided on the outer periphery of the optical fiber in the jacket 13, and the side pressure can be reduced. In addition, two strength members 15 are embedded in the jacket 13 so as to be symmetrical with each other with respect to the center of the multi-core optical fiber cable, and the two tear strings 16 are embedded in the multi-core optical fiber cable. It is embedded in the vicinity of the inner side of the outer jacket 13 so as to be symmetric with respect to the center. The thickness of the jacket 17 in the embedded portion of the tear string 16 is thicker than the thickness of the jacket 13 in the portion other than the embedded portion of the tear string 16. With such a structure, the position of the tear string 16 can be known from the outside, and the jacket 17 can be removed using a cutter or the like. Further, by removing the thickened portion and then forming a shallow cut, the tear string 16 can be easily taken out and the jacket 17 is torn, so that the branching property is also excellent.

  FIG. 4 is a cross-sectional view showing another example of the multi-core optical fiber cable according to the first embodiment of the present invention. As shown in FIG. 1, when a multi-core optical fiber cable is formed by twisting seven optical fiber bundles, one fiber bundle obtained by twisting four single-core coated optical fibers 11 arranged in the center is formed. As shown in FIG. 4, mechanical properties can be improved by replacing the strength member 18.

  As shown in FIG. 4, when the strength member 18 is arranged in the cable core or when the strength fiber is arranged on the outer periphery of the cable core, a structure in which the strength member 15 is not required in the jacket 13 is also conceivable. Moreover, you may use a tensile strength fiber for the part shown by the buffer layer 14 instead of arrange | positioning the tensile strength bodies 15 and 18. FIG.

  FIG. 5 is a sectional view showing still another example of the multi-core optical fiber cable according to the first embodiment of the present invention. That is, a multi-core optical fiber cable having a structure in which the support wire 19 is integrally provided on the upper part of the multi-core optical fiber cable of FIG. 1 is also conceivable, and the tensile body 18 in the cable core or the tensile body 15 in the jacket 13 is omitted. It is also possible to do. In addition, in the multi-core optical fiber cable in the present embodiment example, a structure in which no strength members are arranged is also conceivable.

  FIG. 6 is a cross-sectional view showing a multi-core optical fiber cable according to a second embodiment of the present invention, and FIG. 7 is a view for explaining an optical fiber bundle twisting method according to the second embodiment of the present invention. FIG. As shown in FIG. 6, a plurality of, for example, four single-core coated optical fibers 11 that are concentrically coated on the outer periphery of a photonic crystal fiber provided with a large number of holes near the center are straightened or twisted. A first optical fiber bundle 21 is formed by winding an identification yarn or identification tape 12 around a densely gathered outer periphery, and a plurality of first optical fiber bundles 21 around which the identification yarn or identification tape 12 is wound are formed. For example, an identification yarn or identification tape 22 is wound around the outer periphery of four straight or twisted and closely gathered to form a second optical fiber bundle 23, and the identification yarn or identification tape 22 is further wound. A plurality of second optical fiber bundles 23, for example, seven straight or twisted tightly gathered to form an outer periphery, a buffer layer 14 is interposed on the outer periphery, and press winding / jacket 13 is applied to form a multi-core optical fiber cable 25. To configure. FIG. 7 shows a second optical fiber bundle twisting method, in which four single-core coated optical fibers 11 are twisted and densely assembled, and four first optical fiber bundles 21 are twisted and densely assembled. The optical fiber bundle 23 is formed, and seven second optical fiber bundles 23 are twisted to form a dense assembly. The buffer layer 14 may be omitted.

  FIG. 8 is a cross-sectional view showing another example of the multi-core optical fiber cable according to the second embodiment of the present invention. As shown in FIG. 6, when the second optical fiber bundle 23 is twisted to form a multi-core optical fiber cable, four first optical fiber bundles 21 arranged at the center are twisted 1 By replacing the second fiber bundle 23 of the book with a strength member 24 as shown in FIG. 8, it is possible to improve the mechanical characteristics. Further, the tensile body 15, the tensile fiber or buffer layer 14, the tear string 16, and the support line 19 in the outer jacket 13 can be arranged or omitted as in the first embodiment.

  FIG. 12 is a cross-sectional view showing a multi-core optical fiber cable according to the third embodiment of the present invention. As shown in FIG. 12, a plurality of, for example, four, single-core-coated optical fibers 11 that are concentrically coated on the outer periphery of a photonic crystal fiber provided with a large number of holes in the vicinity of the center are straightened or twisted. An identification yarn or identification tape 12 is wound around the densely gathered outer periphery to form an optical fiber bundle, and a plurality of, for example, seven optical fiber bundles wound with the identification yarn or identification tape 12 are straight or twisted together. A multi-core optical fiber cable 10 is formed by presser winding / jacket 13 on the outer periphery that is densely gathered. In order to obtain an optical fiber having a characteristic that the optical loss does not increase with respect to bending, for example, an optical fiber having an optical loss increase of 0.2 dB / 10 turn or less even when bent at a radius of 15 mm, a photonic such as a holey fiber is used. There are two types of methods: using a crystal fiber and adding a dopant such as GeO to the optical fiber or reducing the core diameter. These two methods can be performed simultaneously. In addition, a buffer layer 14 such as yarn or resin can be provided on the outer periphery of the optical fiber in the jacket 13, and the side pressure can be reduced. In addition, two strength members 15 are embedded in the jacket 13 so as to be symmetrical with each other with respect to the center of the multi-core optical fiber cable, and the two tear strings 16 are embedded in the multi-core optical fiber cable. It is embedded in the vicinity of the inner side of the outer jacket 13 so as to be symmetrical with respect to the center. The thickness of the outer cover 17 of the embedded portion of the strength member 15 is larger than the thickness of the outer cover 13 of the portion other than the embedded portion of the strength member 15. With such a structure, the position of the tear string 16 is known from the outside, and a shallow slit is formed in the outer cover 13 using a cutter or the like, whereby the tear string 16 is easily taken out and the outer cover 13 is torn. Therefore, it has excellent branching properties.

  FIG. 13 is a sectional view showing another example of the multi-core optical fiber cable according to the third embodiment of the present invention. As shown in FIG. 12, when a multi-core optical fiber cable is formed by twisting seven optical fiber bundles, one fiber bundle obtained by twisting four single-core coated optical fibers 11 arranged in the center is formed. As shown in FIG. 13, the mechanical properties can be improved by replacing the strength member 18.

  As shown in FIG. 13, when the strength member 18 is disposed in the cable core or when the strength fiber is disposed on the outer periphery of the cable core, a structure in which the strength member 15 is not required in the jacket 13 is also conceivable. Moreover, you may use a tensile strength fiber for the part shown by the buffer layer 14 instead of arrange | positioning the tensile strength bodies 15 and 18. FIG.

  FIG. 14 is a sectional view showing still another example of the multi-core optical fiber cable according to the third embodiment of the present invention. That is, a multi-core optical fiber cable having a structure in which the support wire 19 is integrally provided on the upper part of the multi-core optical fiber cable in FIG. 12 is also conceivable, and the tensile body 18 in the cable core or the tensile body 15 in the jacket 13 is omitted. It is also possible to do. In addition, in the multi-core optical fiber cable in the present embodiment example, a structure in which no strength members are arranged is also conceivable.

  FIG. 15 is a sectional view showing a multi-core optical fiber cable according to a fourth embodiment of the present invention. As shown in FIG. 15, a plurality of, for example, four single-core coated optical fibers 11 that are coated concentrically on the outer periphery of a photonic crystal fiber having a large number of holes near the center are straightened or twisted. A first optical fiber bundle 21 is formed by winding an identification yarn or identification tape 12 around a densely gathered outer periphery, and a plurality of first optical fiber bundles 21 around which the identification yarn or identification tape 12 is wound are formed. For example, an identification yarn or identification tape 22 is wound around the outer periphery of four straight or twisted and closely gathered to form a second optical fiber bundle 23, and the identification yarn or identification tape 22 is further wound. A multi-core optical fiber cable 2 having a plurality of second optical fiber bundles 23, for example, seven straight or twisted tightly gathered together, and a presser winding / jacket 13 is provided on the outer periphery with a buffer layer 14 interposed therebetween. Constitute a. The buffer layer 14 may be omitted.

  FIG. 16 is a cross-sectional view showing another example of the multi-core optical fiber cable according to the fourth embodiment of the present invention. As shown in FIG. 15, when two second optical fiber bundles 23 are twisted to form a multi-core optical fiber cable, four first optical fiber bundles 21 arranged at the center are twisted 1 By replacing the second fiber bundle 23 of the book with a strength member 24 as shown in FIG. 16, it is possible to improve the mechanical characteristics. Further, the tensile body 15, the tensile fiber or buffer layer 14, the tear string 16, and the support line 19 in the outer jacket 13 can be arranged or omitted as in the third embodiment.

As described above, according to the present embodiment, the low bending loss optical fiber and the photonic crystal fiber provided with a large number of holes near the center take advantage of the feature that the optical loss does not increase with respect to bending, By densely mounting optical fibers, a thin, high-density, lightweight multi-core optical fiber cable is realized. Specifically, it is sufficient to design in consideration of ensuring long-term reliability.Except for plastic rods, tensile bodies, etc. that have been used to reduce optical loss caused by external forces applied to cables, The optical fiber density is increased as much as possible in a multi-core optical fiber cable by gathering the optical fibers densely without causing problems and gathering them in a higher density than conventional optical fiber cables. It is a multi-core optical fiber cable. With this structure, the core density can be set to a high density of, for example, 2.5 cores / mm ² or more.

  In addition, the multi-core optical fiber cable of the present embodiment enables the omission of plastic rods and strength members, realizing an optical fiber cable with a small diameter, high density, light weight and easy design, which can accommodate existing pipes. Space can be used effectively, and when laying a new optical line, the cost of civil engineering equipment investment can be greatly reduced and the construction period can be greatly shortened. Further, since the diameter is smaller than that of the existing optical fiber cable, it is expected that the cable handling performance is improved, the burden on the cable laying operator is reduced, and the cable laying can be performed more quickly. The fiber is subjected to external force at the time of intermediate post-branching by accommodating the core wires at a high density, but since the optical fiber having the characteristic that the optical loss does not increase with respect to bending is used, it is low loss. Can be branched. In addition, in the case of obstacle relocation work, etc., the influence on the optical fiber core wire during service can also be reduced. Also, when negotiating between utility poles, the cable is thin and lightweight, so the tension due to the weight of the cable is reduced, the long-term reliability of the cable is improved, and the aerial distance can be extended.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiment examples may be appropriately combined.

It is sectional drawing which shows the multi-core optical fiber cable which concerns on the 1st Example of this invention. It is a model for demonstrating the optical fiber twisting method which concerns on the 1st Example of this invention. It is a model for demonstrating the optical fiber bundle twisting method which concerns on the 1st Example of this invention. It is sectional drawing which shows the other example of the multi-core optical fiber cable which concerns on the 1st Example of this invention. It is sectional drawing which shows the further another example of the multi-core optical fiber cable which concerns on the 1st Example of this invention. It is sectional drawing which shows the multi-core optical fiber cable which concerns on the 2nd Example of this invention. It is a model for demonstrating the optical fiber bundle twisting method which concerns on the 2nd Example of this invention. It is sectional drawing which shows the other example of the multi-core optical fiber cable which concerns on the 2nd Example of this invention. It is sectional drawing which shows the example of the 100 core optical fiber cable which mounted the 4 core optical fiber tape currently used widely. It is a section schematic diagram showing a photonic crystal fiber. It is a characteristic view which shows the optical loss increase characteristic comparison by the bending of a conventional optical fiber and a photonic crystal fiber. It is sectional drawing which shows the multi-core optical fiber cable which concerns on the 3rd Example of this invention. It is sectional drawing which shows the other example of the multi-core optical fiber cable which concerns on the 3rd Example of this invention. It is sectional drawing which shows the further another example of the multi-core optical fiber cable which concerns on the 3rd Example of this invention. It is sectional drawing which shows the multi-core optical fiber cable which concerns on the example of 4th Embodiment of this invention. It is sectional drawing which shows the other example of the multi-core optical fiber cable which concerns on the example of 4th Embodiment of this invention. It is the schematic which shows the example of the refractive index profile of a conventional optical fiber and a low bending loss optical fiber.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Single-core coated optical fiber, 12 ... Identification thread | yarn or identification tape, 13 ... Presser winding and jacket, 14 ... Buffer layer, 15 ... Strength body, 16 ... Ripped string

Claims (7)

A multi-core optical fiber cable in which single-coated optical fibers coated on the outer periphery of a photonic crystal fiber are assembled,
The single cardiac coated optical fiber to a plurality of periphery which closely by assembling the combined straight or twisted its circumferential surface being in contact with each other to wind the identification yarn or tape, optical wrapped further said identification yarn or tape A plurality of fiber bundles are applied to the outer periphery of the outer periphery, which is tightly gathered by twisting the peripheral surfaces in contact with each other ,
The multi-fiber optical fiber cable is configured such that the optical loss increases to 0.2 dB / 10 turn or less even if the optical fiber is bent at a radius of 15 mm. A multi-core optical fiber cable in which single-coated optical fibers coated on the outer periphery of a photonic crystal fiber are assembled,
The single cardiac coated optical fiber a plurality of combined straight or twisted in a state where the peripheral surface is brought into contact with each other to wind the first identification yarn or tape tightly assembled periphery, said first identification yarn or tape A second identification yarn or tape is wound around the outer periphery of a plurality of optical fiber bundles wound with a plurality of optical fiber bundles and tightly gathered in a state where the peripheral surfaces thereof are in contact with each other , and further the second identification yarn or tape the envelope applied to a plurality of periphery that closely is set by twisting its circumferential surface being in contact with each other through the optical fiber bundle wound,
The multi-fiber optical fiber cable is configured such that the optical loss increases to 0.2 dB / 10 turn or less even if the optical fiber is bent at a radius of 15 mm.   3. The multi-core optical fiber cable according to claim 1, wherein two strength members are embedded in the jacket so as to be symmetrical with each other with respect to the center of the multi-fiber optical fiber cable, and 2 The tear cords are embedded in the jacket so that they are in positions symmetrical to each other with respect to the center of the multi-fiber cable, and the thickness of the jacket of the tear cord embedded portion is other than the portion where the tear cord is embedded. A multi-core optical fiber cable characterized by being thicker than the thickness of the jacket of the part. A multi-core optical fiber cable in which single-core coated optical fibers are coated on the outer periphery of the optical fiber,
The single cardiac coated optical fiber to a plurality of periphery which closely by assembling the combined straight or twisted its circumferential surface being in contact with each other to wind the identification yarn or tape, optical wrapped further said identification yarn or tape A plurality of fiber bundles are applied to the outer periphery of the outer periphery, which is tightly gathered by twisting the peripheral surfaces in contact with each other ,
The multi-fiber optical fiber cable is characterized in that the optical fiber has an optical loss increase of 0.2 dB / 10 turn or less even when bent at a radius of 15 mm by adding a dopant or controlling the core diameter. A multi-core optical fiber cable in which single-core coated optical fibers are coated on the outer periphery of the optical fiber,
The single cardiac coated optical fiber a plurality of combined straight or twisted in a state where the peripheral surface is brought into contact with each other to wind the first identification yarn or tape tightly assembled periphery, said first identification yarn or tape A second identification yarn or tape is wound around the outer periphery of a plurality of optical fiber bundles wound with a plurality of optical fiber bundles and tightly gathered in a state where the peripheral surfaces thereof are in contact with each other , and further the second identification yarn or tape the envelope applied to a plurality of periphery that closely is set by twisting its circumferential surface being in contact with each other optical fiber wound,
The multi-fiber optical fiber cable is characterized in that the optical fiber has an optical loss increase of 0.2 dB / 10 turn or less even when bent at a radius of 15 mm by adding a dopant or controlling the core diameter.   6. The multi-core optical fiber cable according to claim 4, wherein two strength members are embedded in the jacket so as to be symmetrical with each other with respect to the center of the multi-fiber optical fiber cable. The tear string of the book is embedded in the jacket so as to be symmetric with respect to the center of the multi-fiber optical fiber cable, and the thickness of the jacket of the embedded portion of the strength member is other than the embedded portion of the strength member A multi-core optical fiber cable characterized by being thicker than the thickness of the jacket of the part.   7. The multi-core optical fiber cable according to claim 1, wherein tensile strength fibers are arranged on the outer periphery of the cable core.

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