JP2011022540A - Multi-core connection structure of optical fiber and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-core connection structure of an optical fiber which is obtained by a simple process and prevents leakage of light from the side face of a connection part. <P>SOLUTION: The multi-core connection structure 100 of the optical fiber is configured in such a manner that the end parts of a plurality of optical fibers 111 are bundled by a pipe member 120 and integrally fused to form a connecting part 130, each of the optical fibers 111 including a core 111a having a relatively high refractive index and a clad having a relatively low refractive index and coating the core. The pipe member 120 has a layer having a refractive index lower than that of the core 111a of the plurality of optical fibers 111. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical fiber multi-core coupling structure and a method for manufacturing the same.

  As an optical device that collects and emits light from a plurality of light sources, an optical combiner in which one end portions of a plurality of optical fibers are fused and integrated to form a coupling portion is known.

  For example, Patent Document 1 discloses an optical combiner in which a coupling portion is configured by inserting an optical fiber into each hole of a porous capillary and melting and integrating the holes.

JP 2007-165822 A

  By the way, in the optical combiner, when the coupling portion is formed and processed, if the structure of the core and the cladding of the optical fiber collapses, and thus a thinned portion of the cladding is generated, the leakage of light from the core is likely to occur. There is a problem that the coating layer of the optical fiber core wire and the surrounding adhesive are damaged by heat when the light is emitted from the side surface of the coupling portion.

  On the other hand, it is conceivable to use an optical fiber having a thick cladding, but in this case, there is a demerit that the occupied area of the core exposed on the end face of the coupling portion is reduced.

  Further, in the case of the optical combiner disclosed in Patent Document 1, since the optical fibers are melted and integrated in a state where the optical fibers are inserted into the holes of the perforated capillary, the structure of the core and the clad of the optical fiber is less distorted. Therefore, light leakage from the core hardly occurs. However, it is very difficult to form a porous capillary by drilling in quartz.

  An object of the present invention is to provide an optical fiber multi-core coupling structure that can suppress light leakage from the side surface of the coupling portion and can be obtained by simple processing.

In the present invention, one end portions of a plurality of optical fibers each having a core having a relatively high refractive index and a clad having a relatively low refractive index covering the core are bundled by a pipe material, and these are fused together. An optical fiber multi-core coupling structure in which a coupling portion is configured,
The pipe material has a layer having a refractive index lower than that of the cores of the plurality of optical fibers.

In the present invention, one end portions of a plurality of optical fibers each having a core having a relatively high refractive index and a clad having a relatively low refractive index covering the core are bundled by a pipe material, and they are fused and integrated. A method of manufacturing a multi-core coupling structure of optical fibers that forms a coupling portion,
The pipe material has a layer having a refractive index lower than that of the cores of the plurality of optical fibers.

  According to the present invention, a pipe material having a layer having a refractive index lower than that of the core of the optical fiber is used, whereby one end portions of a plurality of optical fibers are bundled and melted and integrated to form a coupling portion. It can be manufactured by processing, and the pipe material has a layer having a refractive index lower than that of the core of the optical fiber, so that light leakage from the side surface of the coupling portion can be suppressed by the light confinement action. .

It is a perspective view which shows the optical combiner of embodiment. It is a perspective view which shows an optical fiber core wire. It is a front view of the end surface of a joint part. (A)-(d) is a cross-sectional view of a pipe material. (A)-(d) is a front view of the end surface of the mode coupling | bond part corresponding to Fig.4 (a)-(d), respectively. It is explanatory drawing which shows the manufacturing method of an optical combiner.

  Hereinafter, embodiments will be described in detail based on the drawings.

  FIG. 1 shows an optical combiner 100 having an optical fiber multi-core coupling structure according to this embodiment. The optical combiner 100 of this embodiment is an optical device used for collecting and emitting laser light from, for example, a plurality of laser oscillators.

  The optical combiner 100 of this embodiment includes a plurality of optical fiber cores 110. The number of optical fiber cores 110 is, for example, 3 to 37 (seven in FIG. 1).

  FIG. 2 shows an optical fiber core wire 110.

  The plurality of optical fiber cores 110 may be configured by the same optical fiber core 110, or may be configured by mixing different optical fiber cores 110. Each of the plurality of optical fiber cores 110 has a configuration in which an optical fiber 111 is covered with a coating layer 112. The optical fiber core wire 110 has, for example, a core wire length of 500 to 5000 mm and a core wire diameter of 250 to 600 μm.

  The optical fiber 111 includes a core 111a provided at the center of the fiber and a clad 111b provided concentrically so as to cover the core 111a. A plurality of pores each extending along the core 111a may be formed in the clad 111b so as to surround the core 111a. The fiber diameter of the optical fiber 111 is, for example, 125 to 450 μm.

  The core 111a may be made of quartz, or may be made of a resin such as an acrylic resin. The quartz core 111a may be doped with a dopant such as germanium (Ge) that increases the refractive index, but is preferably non-doped quartz that is not doped with a dopant. The softening temperature of the core 111a is 1600-1700 degreeC, for example. The core 111a has a relatively high refractive index, for example, about 1.447 for light with a wavelength of 0.975 μm. The core diameter is, for example, 100 to 400 μm.

  The clad 111b may be formed of quartz, or may be formed of a resin such as an acrylic ultraviolet curable resin. The quartz clad 111b may be non-doped quartz that is not doped with a dopant, or may be doped with a dopant such as fluorine (F) or boron (B) that lowers the refractive index. The softening temperature of the clad 111b is, for example, 1400 to 1600 ° C. The clad 111b has a relatively low refractive index and a refractive index lower than that of the core 111a. For example, the clad 111b has a refractive index of about 1.404 with respect to light having a wavelength of 0.975 μm. The thickness of the clad 111b is, for example, 50 to 200 μm.

  The covering layer 112 is made of, for example, a photocurable resin and has a thickness of, for example, 50 to 200 μm.

  As shown in FIG. 3, in the optical combiner 100 of the present embodiment, a plurality of optical fibers 111 from which the coating layers 112 are peeled off are bundled by pipe members 120 at one end portions of the plurality of optical fiber core wires 110. A joint 130 is formed by melting and integrating them. The plurality of optical fibers 111 are basically multimode fibers. However, the optical fiber 111 disposed in the center of the coupling unit 130 may be a multimode fiber or a single mode fiber. Also good.

  The pipe material 120 may be made of quartz or may be made of a resin such as acrylic resin, but is preferably made of the same material as the optical fiber 111. For example, the pipe member 120 has a length of 10 to 50 mm, an outer diameter of 450 to 1800 mm, and an inner diameter of 400 to 1400 mm.

  The pipe material 120 includes a layer having a refractive index lower than that of the cores 111 a of the plurality of optical fibers 111. Specifically, for example, when the material forming the core 111a is pure quartz not doped with a dopant, the pipe member 120 is made of fluorine (F), boron (B), or the like as shown in FIG. 4 (b), (c), and (d), respectively, may be configured by only the doped low-refractive index layer 121 formed of quartz doped with a dopant that lowers the refractive index. In addition, an inner layer, an intermediate layer, or an outer layer of the doped low refractive index layer 121 formed of quartz doped with such a dopant and the other non-doped high refractive index layer 122 may be used. The softening temperature of the doped low refractive index layer 121 is, for example, 1400 to 1600 ° C., and the softening temperature of the non-doped high refractive index layer 122 is, for example, 1600 to 1700 ° C. The refractive index of the doped low refractive index layer 121 is, for example, about 1.404 for light having a wavelength of 0.975 μm, and the refractive index of the non-doped high refractive index layer 122 is, for example, about 1.75 for light having a wavelength of 0.975 μm. 447. In the coupling unit 130, it is preferable that a plurality of optical fibers 111 are bundled in the pipe material 120 in a close-packed manner and fused and integrated. However, in the pipe material 120, the fibers are bundled with a gap between the fibers and melted. It may be integrated. The coupling portion 130 may be formed to have a uniform thickness, or may be tapered toward the end portion so as to correspond to the shape of the connection destination. For example, the coupling part 130 has a length of 5 to 30 mm and an outer diameter of 400 to 1400 μm.

  In the case of the pipe member 120 composed only of the doped low-refractive index layer 121 shown in FIG. 4A, the coupling portion 130 includes the clads 111b of the plurality of optical fibers 111, as shown in FIG. A plurality of cores 111a are arranged in the clad coupling part 131 where the two are coupled to each other at intervals, and a low refractive index layer 132 made of the pipe material 120 is provided so as to cover them. The thickness of the low refractive index layer 132 is, for example, 25 to 200 μm.

  In the case of the pipe member 120 in which the inner layer shown in FIG. 4B is a doped low-refractive index layer 121 and the outer layer outside thereof is a non-doped high-refractive index layer 122, the coupling portion 130 is formed as shown in FIG. As shown in FIG. 2, a plurality of cores 111a are disposed at intervals in a clad coupling portion 131 in which clads 111b of a plurality of optical fibers 111 are coupled to each other, and the pipe material 120 is covered so as to cover them. The low refractive index layer 132 is provided by the inner layer that is the inner peripheral side portion, and the support layer 133 is provided by the outer layer that is the outer peripheral side portion of the pipe material 120 so as to cover it. The thickness of the low refractive index layer 132 is, for example, 5 to 100 μm.

  In the case of the pipe member 120 in which the intermediate layer shown in FIG. 4C is the doped low-refractive index layer 121 and the inner layer and the outer layer outside thereof are configured as the non-doped high-refractive index layer 122, As shown in FIG. 5 (c), a plurality of cores 111a are disposed at intervals in a clad coupling part 131 in which clads 111b of a plurality of optical fibers 111 are coupled to each other so as to cover them. Is provided with a non-doped intermediate layer 134 by an inner layer which is an inner peripheral side portion of the pipe material 120, and a low refractive index layer 132 by an intermediate layer of the pipe material 120 is provided so as to cover it. In this way, the support layer 133 is provided by the outer layer which is the outer peripheral side portion of the pipe material 120. The thickness of the low refractive index layer 132 is, for example, 5 to 100 μm.

  In the case of the pipe member 120 in which the inner layer shown in FIG. 4 (d) is the non-doped portion 122 and the outer layer outside thereof is the doped portion 121, a plurality of coupling portions 130 are formed as shown in FIG. 5 (d). A plurality of cores 111a are disposed in the clad coupling portion 131 where the clads 111b of the optical fiber 111 are coupled to each other, and are the inner peripheral side portions of the pipe member 120 so as to cover them. A non-doped intermediate layer 134 is provided as an inner layer, and a low refractive index layer 132 is provided as an outer layer which is an outer peripheral side portion of the pipe material 120 so as to cover it. The thickness of the low refractive index layer 132 is, for example, 5 to 100 μm.

  In the configuration of the optical combiner 100 of the present embodiment described above, the softening temperature of the pipe material 120 itself or the inner layer that is the inner peripheral side portion thereof is preferably equal to or lower than the softening temperature of the clad 111b of the plurality of optical fibers 111. According to such a configuration, the pipe material 120 melted earlier than the clad 111b or the inner layer, which is the inner peripheral portion thereof, flows into the gap between the optical fibers 111 during the melt processing, thereby the core 111a and the clad 111b of the optical fiber 111. The collapse of the structure can be suppressed. Therefore, the movement of light between the optical fibers 111 can be suppressed, and for example, the occurrence of unevenness in the emission pattern when emitted to the lens system can be suppressed.

  The pipe material 120 itself or the inner layer which is the inner peripheral side portion thereof preferably has the same refractive index as the clad 111b of the plurality of optical fibers 111, and is formed of the same material as the clad 111b of the plurality of optical fibers 111. May be.

  Moreover, it is preferable that the pipe material 120 itself or the outer layer that is the outer peripheral side portion thereof has a softening temperature higher than the other portions of the pipe material 120 and the cores 111 a and the clads 111 b of the plurality of optical fibers 111. According to such a configuration, the pipe member 120 or the outer layer which is the outer peripheral side portion thereof is most difficult to melt at the time of melting processing, whereby the joint portion 130 can be formed in a state in which the outer shape of the pipe member 120 is retained.

  The optical combiner 100 of the present embodiment described above can be used for a purpose in which light is incident on a plurality of optical fibers 111 from a light source or a fiber laser, and is propagated and emitted from the coupling unit 130. It can also be used in applications where light is incident on the light source, propagated, distributed from the plurality of optical fibers 111, and emitted.

  The optical combiner 100 of the present embodiment peels the coating layer 112 at one end of the plurality of optical fiber cores 110, and bundles one end of the plurality of optical fibers 111 with a pipe member 120 as shown in FIG. It can be manufactured by heating and fusing to form the joint 130, and cleaving the part to form an end face and polishing the end face. At this time, it is preferable not to form a gap in the pipe material 120. For this reason, it is preferable to provide the optical fiber 111 in a close-packed configuration, and a filler made of the same material as that of the clad 111b in the gap between the fibers. May be provided. Moreover, it is preferable to depressurize the inside of the pipe material 120, and the pressure is 0.01-0.1 MPa, for example. Examples of the heating means include a torch and a carbon dioxide laser. The heating temperature is, for example, 1400 to 1800 ° C. although it depends on the material of the optical fiber 111 and the pipe material 120. When the softening temperature of the pipe material 120 itself or the outer layer that is the outer peripheral side portion thereof is higher than the softening temperatures of the other portions of the pipe material 120 and the cores 111a and clads 111b of the plurality of optical fibers 111, the outer shape of the pipe material 120 From the viewpoint of forming the coupling portion 130 in a state where the shape is maintained, the heating temperature is preferably set to a temperature intermediate between the former and the latter.

  According to the optical combiner 100 of the present embodiment having the above configuration, the pipe material 120 having a layer having a refractive index lower than that of the core 111a of the optical fiber 111 is used, thereby bundling one end portions of the plurality of optical fibers 111. And the pipe member 120 has a layer having a refractive index lower than that of the core 111a of the optical fiber 111, thereby confining light. By the action, leakage of light from the side surface of the coupling portion 130 can be suppressed.

  In the present embodiment, the light-proof combiner 100 having the coupling portion at one end is taken as an example, but the present invention is not particularly limited thereto, and may be a heat-resistant bundle having the coupling portion at both ends.

  In the present embodiment, the coupling portion 130 is the exit end. However, the present invention is not particularly limited to this, and the coupling portion 130 may have a configuration in which another optical fiber core wire is connected to the exit end. Further, an optical coupling device can be configured by connecting a rod material made of a single material such as pure quartz.

  INDUSTRIAL APPLICABILITY The present invention is useful for an optical fiber multi-core coupling structure and a manufacturing method thereof.

100 Optical combiner (optical fiber multi-core coupling structure)
110 Optical fiber core wire 111 Optical fiber 111a Core 111b Clad 112 Coating layer 120 Pipe material 121 Doped low refractive index layer
122 non-doped high refractive index layer 130 coupling portion 131 clad coupling portion 132 low refractive index layer 133 support layer 134 non-doped intermediate layer

Claims (5)

One end portions of a plurality of optical fibers each having a core having a relatively high refractive index and a clad having a relatively low refractive index covering the core are bundled by a pipe material, and they are fused and integrated to form a coupling portion. Is a multi-core coupling structure of optical fibers,
The pipe material is a multi-core coupling structure of optical fibers having a layer whose refractive index is lower than that of the cores of the plurality of optical fibers. In the multi-fiber coupling structure of an optical fiber according to claim 1,
An optical fiber multi-core coupling structure in which a softening temperature of at least an inner peripheral side portion of the pipe material is equal to or lower than a softening temperature of a clad of the plurality of optical fibers. In the multi-core coupling structure of an optical fiber according to any one of claims 1 and 2,
An optical fiber multi-core coupling structure in which at least an outer peripheral side portion of the pipe material has a softening temperature higher than other portions of the pipe material and the cores and clads of the plurality of optical fibers. One end portions of a plurality of optical fibers each having a core having a relatively high refractive index and a clad having a relatively low refractive index covering the core are bundled by a pipe material, and they are fused and integrated to form a coupling portion. A manufacturing method of a multi-core coupling structure of optical fibers forming
The said pipe material is a manufacturing method of the multi-core coupling structure of the optical fiber which has a layer whose refractive index is lower than the core of said some optical fiber. In the manufacturing method of the multi-fiber coupling structure of the optical fiber according to claim 4,
A method of manufacturing an optical fiber multi-core coupling structure in which the inside of a pipe material is depressurized when a portion where one end of the optical fiber is bundled with a pipe material is melted.

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