WO2003083546A1

WO2003083546A1 - Optical fiber core

Info

Publication number: WO2003083546A1
Application number: PCT/JP2003/004064
Authority: WO
Inventors: Koji Kimura; Shogo Ikunishi
Original assignee: Mitsubishi Cable Industries, Ltd.
Priority date: 2002-03-29
Filing date: 2003-03-31
Publication date: 2003-10-09
Also published as: AU2003221001A1; JPWO2003083546A1

Abstract

An optical fiber core (10) being employed for laser guide or light guide. The optical fiber core (10) comprises an optical fiber (11) having a core (11a) at the center of the fiber and a clad (11b) covering the core (11a), a low refractive index reinforcing layer (12) provided to cover the optical fiber (11) and having a refractive index lower than that of the optical fiber (11) at at least a part touching the optical fiber (11), and an outer protective layer (14) provided to cover the low refractive index reinforcing layer (12) and being strippable independently thereof.

Description

Membrane Optical fiber core technology

The present invention relates to an optical fiber core for a laser guide and an optical fiber core for a light guide.

As shown in FIG. 7, an optical fiber core 10, which is generally used as a laser guide or the like, has a core 11a serving as the center of the fiber and a cladding 11b covering the core 11a '. An optical fiber 11, which has: a silicon resin layer 13 ′ provided to cover the optical fiber 11 ′; and a nylon resin outer protection provided to further cover the silicon resin layer 13 ′. And a layer 14 ′.

JP 2000-81552A discloses a non-peelable thin film made of a synthetic resin having good adhesion to a cladding on a single-mode optical fiber. FIG. 1 shows that primary and secondary coatings are formed, and describes that the connection loss is thereby reduced.

By the way, as shown in Fig. 8A, when a general connector 50 'is attached to the fiber end of the optical fiber core 10', usually, a predetermined length from the fiber end of the optical fiber 10 'is used. Separate the silicone resin layer 13 'and the outer protective layer 14', insert them from the rear end of the connector 50 ', and pass the exposed optical fiber 11 to the ferrule 51'. At the same time, the adhesive 54 'is injected into the gap to fix the optical fiber' core 10 '.

On the other hand, as shown in Fig. 8B, when a connector 20 for attaching the optical fiber 10 for the laser guide for transmitting the laser light to the fiber end of the optical fiber 10, The silicone resin layer 13 'and the outer protective layer 14 for a predetermined length are peeled off from the fiber end of the optical fiber' core 10 'and the connector is Insert the exposed optical fiber 11 'into the space 22' formed at the distal end of the connector 20, and insert the optical fiber 11 'with the ferrule 21 mechanically. And fixing the optical fiber core 10 'by caulking or the like at the rear end. In other words, the ferrule 21 is designed to prevent high heat from being applied by the laser beam and to use no adhesive. The peeling of the silicone resin layer 13 and the outer protective layer 14 'is also based on this viewpoint. At this time, if the peel length of the silicon resin layer 13 and the outer protective layer 14' is short, the outer protective layer There is a risk that high heat is applied to 14 'to melt it.

Also, as shown in Fig. 8C, a multi-core connector 30 for attaching to the optical fiber core 10 for the laser guide for transmitting the laser light is connected to the fiber end of the optical fiber core 10. When attaching to the connector, peel off the silicon resin layer 13 'and outer protective layer 14' for a considerable length from the fiber end, bundle them and connect them

A method is adopted in which the optical fiber 11 ', which is inserted from the rear end of 30' and exposed by the ferrule 31 ', is mechanically held and the optical fiber core 10' is fixed at the rear end. The reason why the silicone resin layer 13 and the outer protective layer 14 'are peeled off is to make the fiber ends close to each other. At this time, if the peel length of the silicon resin layer 13 and the outer protective layer 14 is short, However, it is difficult for the outer protective layers 14 'to interfere with each other due to interference between the outer protective layers 14'. In addition, the optical fiber core wire 10 'is sharply bent near the ferrule 31', which is apt to be broken, and the laser light is emitted. This can cause pattern failure.

In addition, as shown in Fig. 8D, when the multi-core connector 40, which is attached to the so-called light guide optical fiber core 10 ', is attached to the fiber end of the optical fiber core 10', the fiber ends from the fiber end. peeled considerable silicone resin layer 13 ⁵ and an outer protective layer 14, equivalent to the length, it plurality of bundled connector 40, inserting the rear end portion or these became exposed in Fell Ichiru 41 'it A method is adopted in which the optical fiber 11 1 ′ is held and the adhesive 44 ′ is injected into the gap to fix the optical fiber core 10. The silicon resin layer 13 'and the outer protective layer 14 are peeled off because it is necessary to prevent the outer protective layer 14 from interfering with each other when a plurality of optical fibers 11' are bundled in order to increase the light concentration. At this time, the silicon resin layer 13 ^If the peel length of the outer protective layer 14 and the outer protective layer 14 is short, the outer protective layers 14 'will interfere with each other and it will be difficult to bundle the optical fibers 11 at a high density.

However, in these cases, the exposed optical fiber 11 'does not have any protective layer, so that the mechanical strength is reduced at that portion, making it difficult to handle and mounting the connector. There is a problem that the workability is poor.

Also, in the optical fiber core wire 10 for the laser guide and the light guide, the light leaking from the clad lib 'to the outside is lost as it is, so it is desirable that such light leakage is small. It is. Disclosure of the invention

An object of the present invention is to provide an optical fiber core for a laser guide and an optical fiber core for a light guide, which maintain mechanical strength even when the outer protective layer is peeled off and have a low loss due to light leakage. It is to provide.

The present invention achieves the above-mentioned object by interposing a low-refractive-index reinforcing layer having a refractive index lower than that of a cladding at least in a portion in contact with the optical fiber between the optical fiber and the outer protective layer.

Specifically, the optical fiber core of one embodiment of the present invention is premised on a laser guide or a light guide.

An optical fiber having a core that forms the center of the fiber and a cladding that covers the core;

A low-refractive-index reinforcing layer provided so as to cover the optical fiber and having at least a portion in contact with the optical fiber having a lower refractive index than the cladding;

An outer protective layer provided so as to cover the low-refractive-index reinforcing layer and detachable independently of the low-refractive-index reinforcing layer;

Is provided.

According to the above configuration, when the connector is attached to the end of the fiber, the low refractive index reinforcing layer can be left even if the outer protective layer is peeled off. In this case, a low-refractive-index reinforcing layer exists in the other portion where the outer protective layer is peeled off, and the low-refractive-index reinforcing layer reduces the mechanical strength of the optical fiber core. Can be secured. Therefore, even if the outer protective layer is peeled off, the handling is easy, and the workability of the connection work is good.

In addition, since at least the portion of the low-refractive-index reinforcing layer that contacts the optical fiber has a lower refractive index than the cladding, propagating light is confined in the optical fiber, and light leakage from the cladding is suppressed. The loss due to leakage can be kept low. The optical fiber core of one embodiment of the present invention may have an outer diameter of the optical fiber of 100 to 150.

In one embodiment of the present invention, the low-refractive-index reinforcing layer includes: an inner low-refractive-index layer on the optical fiber side; and an outer reinforcing layer that covers the inner low-refractive-index layer. It may be something.

According to such a configuration, the operation of the present invention can be performed without using a single material having both the low refractive index property and the reinforcing property, and the range of material selection is wide. Become.

In this case, the optical fiber core wire of one embodiment of the present invention may have a thickness of the inner low refractive index layer of 10 to 20 O ^ drn. Further, the thickness of the outer reinforcing layer may be 50 to 100 zm.

In an optical fiber core according to one aspect of the present invention, a connector is attached to an end of a fiber, and in the connector, the outer protective layer is peeled off and the optical fiber is connected to the low refractive index reinforcing layer. It may have a portion covered with.

According to such a configuration, in the portion where the outer reinforcing layer is peeled off in the connector, the optical fiber is protected by the low refractive index reinforcing layer, and the mechanical strength is secured.

In the optical fiber core wire according to one aspect of the present invention, the low-refractive-index reinforcing layer may be formed of an ultraviolet-curable resin.

According to such a configuration, the operation of the present invention is more specifically performed. Further, the low-refractive-index reinforcing layer can be formed only by adhering a liquid uncured resin to the optical fiber and irradiating ultraviolet rays, so that the production of the optical fiber core is easy.

Further, according to the present invention, when the cladding of the optical fiber is composed of a plurality of layers having mutually different refractive indices, the refractive index of the low refractive index reinforcing layer is made lower than that of the cladding having the highest refractive index. This achieves the above object. Specifically, the optical fiber core according to another embodiment of the present invention is premised on a laser guide or a light guide.

And an optical fiber comprising: a core that forms the center of the fiber; a cladding that covers the core and is composed of a plurality of layers having mutually different refractive indexes;

A low-refractive-index reinforcing layer provided so as to cover the optical fiber and having at least a portion in contact with the optical fiber having a lower refractive index than the layer having the highest refractive index of the clad;

Is provided.

An optical fiber core wire according to another aspect of the present invention may have an outer diameter of the optical fiber of 100 to 1500 zm.

In another aspect of the present invention, the low-refractive-index reinforcing layer includes: an inner low-refractive-index layer on the optical fiber side; and an outer reinforcing layer that covers the inner low-refractive-index layer. It may be something.

In this case, the optical fiber core wire according to another aspect of the present invention may have a thickness of the inner low refractive index layer of 10 to 200 m. Further, the outer reinforcing layer may have a thickness of 50 to 100 m.

According to another aspect of the present invention, there is provided an optical fiber having a connector attached to an end of a fiber, in which the outer protective layer is peeled off and the optical fiber is connected to the low refractive index reinforcing layer. It may have a portion covered with. In an optical fiber core wire according to another aspect of the present invention, the low-refractive-index reinforcing layer may be formed of an ultraviolet-curable resin. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a longitudinal sectional view of an optical fiber core for laser guide according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing a state in which a connector is attached to the optical fiber for a laser guide according to the first embodiment of the present invention. FIG. 3 is a view showing a state in which a connector is attached to an optical fiber for a laser guide according to a second embodiment of the present invention.

FIG. 4 is a view showing a state in which a connector is attached to a light guide optical fiber core according to Embodiment 3 of the present invention.

FIG. 5 is a longitudinal sectional view of an optical fiber according to Embodiment 4 of the present invention.

FIG. 6 is a view showing a refractive index profile of an optical fiber according to Embodiment 4 of the present invention.

FIG. 7 is a longitudinal sectional view of a conventional optical fiber core.

8A to 8D are views showing a state in which various connectors are attached to a conventional optical fiber core. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)

FIG. 1 shows an optical fiber core 10 for a laser guide according to Embodiment 1 of the present invention.

The optical fiber core 10 covers the optical fiber 11, the inner low-refractive-index layer 12 a provided to cover the optical fiber 11, and the inner low-refractive-index layer 12 a. Outer reinforcing layer 1 2b provided on the outer side, silicon resin layer 13 provided so as to cover outer reinforcing layer 1 2b, and outer protective layer 1 provided so as to cover silicon resin layer 13 4 is a laminated body.

The optical fiber 11 has an outer diameter of approximately 100 to 1500 zm, and has a high refractive index core 11a forming the center of the fiber and a low refractive index core covering the core 11a. The cladding 11b is integrated with the cladding 11b. The core 11a is made of pure quartz, while the cladding 11b is made of quartz doped with fluorine or the like for lowering the refractive index.

The inner low-refractive-index layer 12a has a thickness of approximately 100 to 200 μm and is formed of an ultraviolet curable resin having a refractive index lower than 1 lb of the cladding of the optical fiber 11. . The outer reinforcing layer 12 b has a thickness of approximately 50 to 100 μm, It is formed of an outside line curing resin. The inner low-refractive-index layer 12a and the outer reinforcing layer 12b formed of an ultraviolet-curable resin are made of a resin material in which a urethane acrylate-based polymer and a radical generator are added to the optical fiber 11. It can be formed by depositing and irradiating it with ultraviolet light. The inner low refractive index layer 12a and the outer reinforcing layer 12b are integrated to form the low refractive index reinforcing layer 12. The silicon resin layer 13 has a thickness of, for example, about 125 zm, and functions to prevent the optical fiber 11 from being greatly distorted when the optical fiber core 10 is bent.

The outer protective layer 14 is a nylon resin layer having a thickness of, for example, about 200 m, so that an excessive bending strain is not applied to the optical fiber 11 when the optical fiber core 10 is bent. At the same time, optical finos function to protect "11" from external factors such as external force.

As shown in FIG. 2, the connector 20 attached to the optical fiber core 10 for the laser guide has a space 22 at the distal end, and a ferrule 21 and a ferrule 21 after the space 22. After each thread 21, a fiber passage 23 is formed. When attaching the connector 20 to the fiber end, first, as shown in Fig. 1, the outer protective layer 14 of a predetermined length is peeled off from the fiber end, and at the same time, the ferrule 21 and the space 22 By peeling off the low-refractive-index reinforcing layer 12 of the required minimum length, the light having both the low-refractive-index reinforcing layer 12 and the outer protective layer 14 peeled off from the optical fiber core wire 10. The fiber 11 forms a bare part, and the outer protective layer 14 forms a part where the optical fiber 11 is peeled off and is covered with the low refractive index reinforcing layer 12. Here, the reason why both the outer protective layer 14 and the low refractive index reinforcing layer 12 are peeled off is to prevent them from being damaged by the laser beam. The reason why only the outer protective layer 14 is peeled off is to improve the connector workability.

Next, the fiber end is inserted from the rear end of the connector 20, and the optical fiber 11 exposed to the extent that the front end of the low refractive index reinforcing layer 12 abuts the rear end of the ferrule 21 is connected to the ferrule 21. By inserting the optical fiber 11 into the space 22, the optical fiber 11 is held by the ferrule 21, and the optical fiber 10 is fixed at the rear end of the connector 20 by caulking or the like. As a result, the fiber The optical fiber core wire 10 in the through portion 23 has only the outer protective layer 14 peeled off and is covered and protected by the low refractive index reinforcing layer 12.

According to the optical fiber core 10 for a laser guide having the above configuration, when the connector 20 is attached to the end of the fiber, the low refractive index reinforcing layer 12 remains even after the outer protective layer 14 is peeled off. If the optical fiber 11 is exposed only in the minimum necessary portion corresponding to the space 22 and the ferrule 21, the other fiber passages 2 3 from which the outer protective layer 14 has been peeled off The low refractive index reinforcing layer 12 is present in the portion of the optical fiber core 10. The mechanical strength of the optical fiber core 10 can be ensured by the low refractive index reinforcing layer 12. Therefore, even if the outer protective layer 14 is peeled off, the handling is easy, and the workability of mounting the connector 20 is improved.

Also, since the inner low refractive index layer 12a in contact with the optical fiber 11 has a lower refractive index than the cladding 11b, one laser beam is confined in the optical fiber 11 and the laser 11b is emitted from the cladding 11b. Since laser light leakage is suppressed, energy loss due to light leakage can be kept low.

(Embodiment 2)

The optical fiber core for a laser guide according to the second embodiment of the present invention has the same configuration as that of the first embodiment. Therefore, the optical fiber cores and their respective parts are denoted by the same reference numerals as in the first embodiment.

As shown in FIG. 3, the connector 30 attached to the fiber end of the optical fiber core 10 for the laser guide has a ferrule capable of holding a large number of optical fiber cores 10 in a bundle. After the ferrule 31 and the ferrule 31, a fiber passage 33 is formed.

When attaching the connector 30 to the end of the fiber, first, as in the case of Fig. 1, it is necessary to peel off the outer protective layer 14 of a predetermined length from the end of the fiber and make it slightly longer than the thickness of the ferrule 31. By stripping the minimum low refractive index reinforcing layer 12, the optical fiber core 10 has an optical fiber 11 with both the low refractive index reinforcing layer 12 and the outer protective layer 14 separated. Is formed, and a portion where the outer protective layer 14 is peeled off and the optical fiber 11 is covered with the low refractive index reinforcing layer 12 is formed. Here, both the outer protective layer 14 and the low refractive index reinforcing layer 12 are separated by laser This is to prevent damage from light. In addition, the reason why only the outer protective layer 14 is peeled off is that it is necessary to prevent the outer protective layers 14 from interfering with each other at the fiber passage portion 33 because the fiber ends are close to each other. Further, it is possible to prevent the optical fiber core wire 10 from being sharply bent near the ferrule 31 to damage the optical fiber core wire 10 or to prevent the laser light pattern defect from being caused by the bending. That's why.

Next, insert the fiber ends of the plurality of optical fibers 10 from the rear end of the connector 30, insert the exposed portions of the optical fibers 11 into the ferrules 31, hold them, and At the rear end, the optical fiber 10 is fixed by caulking or the like. As a result, the optical fiber core wire 10 in the fiber passage portion 33 is separated from the outer protective layer 14 between the fibers by preventing only the outer protective layer 14 from peeling off and has a low refractive index. The coating is protected by the reinforcing layer 12. In addition, a pattern defect of one laser beam is prevented.

Functions and effects are the same as those of the first embodiment.

(Embodiment 3)

The optical fiber core for a light guide according to the third embodiment of the present invention has the same configuration as that of the first embodiment. Accordingly, the optical fiber cores and their respective parts are denoted by the same reference numerals as in the first embodiment.

As shown in FIG. 4, a connector 40 attached to the fiber end of the optical fiber core 10 for the light guide has a ferrule capable of holding a large number of optical fiber cores 10 individually. After the fiber 41 and the ferrule 41, fiber passages 43 are formed respectively.

When attaching the connector 40 to the fiber end, first, the outer protective layer 14 of a predetermined length is peeled from the fiber end, so that only the outer protective layer 14 is peeled off from the optical fiber core 10. In addition, the optical fiber 11 forms a portion covered with the low refractive index reinforcing layer 12. The reason why the outer protective layer 14 is peeled off is to prevent the outer protective layers 14 from interfering with each other when a plurality of optical fibers 11 are bundled in order to increase the degree of light collection. At this time, the low-refractive-index reinforcing layer 12 having a slightly longer end portion may be peeled off. By doing so, the density of the bundle of the plurality of optical fibers 11 can be increased. Next, insert the ends of the plurality of optical fibers 10 from the rear end of the connector 40, and insert the bundle of optical fibers 11 covered only with the low refractive index reinforcing layer 12 into the ferrule 41. The fiber layer through hole 43 is filled with an adhesive 44 to fix the optical fiber core 10. As a result, the optical fiber core wire 10 in the fiber passage portion 43 is separated from the outer protection layer 14 between the fibers by preventing only the outer protection layer 14 from peeling off and has a low refractive index. According to the optical fiber core 10 for a light guide having the above configuration, which is covered and protected by the modulus reinforcing layer 12 and the adhesive 44, when the connector 40 is attached to the end of the fiber, Even if the protective layer 14 is peeled off, the low-refractive-index reinforcing layer 12 can be left, so the ferrule 41 from which the outer protective layer 14 has been peeled off and the fiber passage portion 4 3 have the low-refractive-index reinforcing layer 1. The low refractive index reinforcing layer 12 ensures the mechanical strength of the optical fiber core 10. Therefore, even if the outer protective layer 14 is peeled off, the handling is easy, and the workability of the mounting work of the connector 40 is improved.

In addition, since the inner low refractive index layer 12a has a lower refractive index than the cladding 11b, the propagating light is confined in the optical fiber 11 ', and light leakage from the cladding 11b is suppressed. Therefore, loss due to light leakage can be kept low.

(Embodiment 4)

FIG. 5 shows an optical fiber core wire 10 according to Embodiment 4 of the present invention. In addition, each part of the optical fiber core wire 10 is denoted by the same reference numeral as in the first embodiment.

The optical fiber core 10 covers the optical fiber 11, the inner low-refractive-index layer 12 a provided to cover the optical fin 11, and the inner low-refractive-index layer 12 a. The provided outer reinforcing layer 12b, the silicon resin layer 13 provided to cover the outer reinforcing layer 12b, and the outer protective layer 14 provided to cover the silicon resin layer 13 And a laminate comprising:

The optical fino'11 has an outer diameter of approximately 100 to 150〃m and has a high refractive index core 11a that forms the center of the fiber and a low refractive index that covers the core 11a. And the clad 11 1b are integrated. The core 11a is formed of pure quartz. The cladding 1 1b has a two-layer structure consisting of an inner part 1 1 1b and an outer part 1 1 2b. The former is made of quartz doped with fluorine or the like that lowers the refractive index, while the latter is made of pure quartz. Thus, the outer portion 1 1 2b has a higher refractive index than the inner portion 1 1 lb.

The inner low-refractive-index layer 12a has a thickness of approximately 10 to 200 m, and the outer portion 1 1 2b, which is the layer having the highest refractive index in the cladding 11b of the optical fiber 11. It is made of UV curable resin with a lower refractive index. However, the refractive index of the inner low refractive index layer 12 a may be lower than the inner part 11 lb as shown by the line A in FIG. 6 or the inner part 11 1 as shown by the line B. It may be higher than lb and lower than the outer part 1 1 2b. The outer reinforcing layer 12b has a thickness of approximately 50 to 100 zm and is formed of a high-strength ultraviolet curable resin. The inner low-refractive index layer 12a and the outer reinforcing layer 12b, which are formed of an ultraviolet curable resin, adhere a resin material obtained by adding a radical generator to a urethane acrylate-based polymer to the optical fiber 11. It can be formed by irradiating it with ultraviolet light. The inner low refractive index layer 12a and the outer reinforcing layer 12b constitute a low refractive index reinforcing layer 12 as a body.

The silicon resin layer 13 has a thickness of, for example, about 125 μm, and functions to prevent a large distortion from being applied to the optical fiber 11 when the optical fiber core 10 is bent. Fulfill.

The outer protective layer 14 is a nylon resin layer having a thickness of, for example, about 200, so that an excessive bending strain is not applied to the optical fiber 11 when the optical fiber core 10 is bent. And a function of protecting the optical fiber 11 from external factors such as external force.

This optical fiber core wire 10 is used for a laser guide or a light guide as in the first to third embodiments.

(Other embodiments)

In the first to fourth embodiments, the optical fiber core 10 made of quartz is used. However, the present invention is not particularly limited to this, and an optical fiber core made of resin may be used.

Further, in Embodiments 1 to 4, the low refractive index protective layer, the inner low refractive index layer 12a, and the outer reinforcing layer 12b are used, but the present invention is not limited to this. It may be formed of a single layer.

Further, in the first to fourth embodiments, the low-refractive-index reinforcing layer 12 is formed of a urethane acrylate-based ultraviolet-curable resin. However, the present invention is not particularly limited to this, and other materials may be used. Good.

In the first to fourth embodiments, the optical fiber 11 is made of pure silica in which the core 11 a is formed of pure quartz while the clad 11 b is doped with fluorine or the like that lowers the refractive index. It is assumed that the core is made of quartz doped with Ge, which increases the refractive index, while the cladding is made of pure quartz. Good.

Further, in Embodiment 4 described above, the 1 lb of the clad has a two-layer structure of the inner portion 11 lb and the outer portion 11 12 b. However, the present invention is not limited to this, and it is a multilayer structure. Is also good.

Industrial applicability

As described above, the optical fiber core wire according to the present invention can be suitably used for a laser guide or a light guide.

Claims

The scope of the claims

1. an optical fiber used for a laser guide or a light guide, the optical fiber having a core forming the center of the fiber and a cladding covering the core;

With fiber optic core.

2. In the optical fiber cable described in claim 1,

An optical fiber core having an optical fiber with an outer diameter of 100 to 1500 m.

3. In the optical fiber cable described in claim 1,

An optical fiber cable, wherein the low-refractive-index reinforcing layer includes: an inner low-refractive-index layer on the optical fiber side; and an outer reinforcing layer that covers the inner low-refractive-index layer.

4. In the optical fiber cable described in claim 3,

An optical fiber core having a thickness of the inner low refractive index layer of 10 to 200 m.

5. The optical fiber according to claim 3,

An optical fiber having a thickness of the outer reinforcing layer of 50 to 100 m.

6. In the optical fiber core described in claim 1,

A connector is attached to the end of the fiber,

An optical fiber core having a portion in which the outer protective layer is peeled off and the optical fiber is covered with the low refractive index reinforcing layer in the connector.

7. In the optical fiber cable described in claim 1,

An optical fiber cable in which the low-refractive-index reinforcing layer is formed of an ultraviolet-curable resin.

8. An optical fiber core used for a laser guide or a light guide, comprising a core that forms the center of the fiber and a cladding that covers the core and has a plurality of layers having different refractive indexes. And an optical fiber comprising:

The optical fiber is provided so as to cover the optical fiber and at least contacts the optical fiber. A low-refractive-index reinforcing layer whose portion has a lower refractive index than the highest-refractive-index layer of the cladding;

With fiber optic core.

9. The optical fiber according to claim 8, wherein:

An optical fiber having an optical fiber with an outer diameter of 100 to 150 m.

10. The optical fiber cable according to claim 8,

11. In the optical fiber core wire described in claim 10,

An optical fiber having a thickness of the inner low refractive index layer of 10 to 200 / m.

1 2. In the optical fiber core wire described in claim 10,

An optical fiber having a thickness of the outer reinforcing layer of 50 to 100 μm.

1 3. In the optical fiber cable described in claim 8,

A connector is attached to the fiber end,

14. In the optical fiber core wire described in claim 8,

An optical fiber core wherein the low-refractive-index reinforcing layer is formed of an ultraviolet-curable resin.