WO2006025144A1

WO2006025144A1 - Bundle fiber

Info

Publication number: WO2006025144A1
Application number: PCT/JP2005/010970
Authority: WO
Inventors: Tetsuya Otosaka; Jun Abe
Original assignee: Shin-Etsu Chemical Co., Ltd.
Priority date: 2004-09-02
Filing date: 2005-06-15
Publication date: 2006-03-09
Also published as: KR20060043019A; JP2006072025A; TW200613229A

Abstract

Disclosed is a bundle fiber (200) obtained by tying a plurality of optical fibers (100) in a bundle. In the end face of an integrated part (130) which is formed in the end portion on the guided light incident side, the area ratio of the material constituting waveguides is not less than 90% and not more than 100%. Consequently, more light can be introduced into the bundle fiber from the incident end face.

Description

Specification

Bundled fiber technology

[0001] The present invention relates to a bundle fiber. More specifically, the present invention relates to a bundle fiber formed by bundling a plurality of optical fibers.

[0002] Regarding designated countries where incorporation by reference of documents is permitted, the contents described in the following application are incorporated into this application by reference and made a part of the description of this application. Japanese Patent Application No. 2004-256031 (Filing date: September 2, 2004)

Background art

[0003] As one of media used for light transmission, there is a bundle fiber in which optical fibers are bundled. The light irradiated on the end face of the bundle fiber is not all guided into the bundle fiber. The reason is that since the optical fiber has a circular cross-sectional shape, there is a gap between the individual optical fibers in the bundle fiber in which the optical fiber is bundled, and the light irradiated to the gap is guided in the optical fiber. This is because there is nothing to do.

[0004] As a measure for increasing the incident efficiency of guided light to a bundle fiber, Patent Document 1 describes that a plurality of optical fibers are filled through a quartz sleeve and the ends of the bundle are melted together. It has been proposed to eliminate gaps between individual optical fibers.

Patent Document 1: Japanese Patent Laid-Open No. 08-304642

Disclosure of the invention

Problems to be solved by the invention

Many optical fibers have a low refractive index cladding portion around the core necessary for confining the guided light in the core portion. The light incident on the cladding is not basically guided into the core. Therefore, even if the gap between the optical fibers is eliminated by the method of Patent Document 1, the ratio of the core to the waveguide at the incident side end face (hereinafter referred to as “core filling factor”) is still Not 100%.

[0006] For example, a typical optical fiber used for a bundle fiber has a core diameter of about 200 μm and a cladding diameter of about 240 m. Described in Patent Document 1 using such an optical fiber When a bundle fiber with this structure is manufactured, its core filling factor is only about 69.4%. As described above, since the coupling rate at the incident-side end face is low, the overall transmission efficiency of the bundle fiber, which is a high-density optical transmission medium, is sufficiently high.

Means for solving the problem

In view of the above problems, as a first embodiment of the present invention, a bundle fiber in which a plurality of optical fibers are bundled, and a material for forming a core of the optical fiber on the incident side end face of the guided light! Provided is a bundled fiber characterized in that the ratio of area occupied by it is 90% or more and 100% or less in terms of area ratio. As a result, most of the incident-side end face of the bundle fiber is formed of the waveguide material, so that the light incident on the end face is efficiently coupled to the waveguide.

[0008] Further, as one embodiment, in the bundle fiber, the optical fibers are integrated with each other at the incident side end face by melting. As a result, the incident-side end surfaces are united, and all the light incident on the bundle fiber becomes guided light. In addition, since there is no foreign matter on the incident optical path, the bundle fiber can be efficiently coupled.

[0009] In another embodiment, in the bundle fiber, the optical fiber is a holey fiber. As a result, the member forming the incident side end face of the bundle fiber is formed of a single material from the beginning, and the incident side end face of a single material can be formed by simple processing.

[0010] As another embodiment, in the bundle fiber, the incident-side end face is formed of a holey fiber in which the holes are collapsed. As a result, the incident-side end face of the bundle fiber is formed of a waveguide material having no defects, and high-efficiency coupling can be achieved.

[0011] As another embodiment, in the above-mentioned bundle fiber, the material of the holey fiber is pure quartz glass. In still another embodiment, the bundle fiber is quartz glass doped with at least one of fluorine and hydroxyl groups. Furthermore, as another embodiment, each of the optical fibers is made of pure silica glass, or a core that also has a quartz glass power doped with at least one of fluorine and a hydroxyl group, and a cladding that also has a silica glass power doped with fluorine. And have. As a result, the incident side end face of the bundle fiber can be formed of a material suitable for guided light, and, for example, a bundle fiber with little deterioration against ultraviolet rays or the like is realized.

[0012] As another embodiment, in the above-mentioned bundle fiber, each of the optical fibers is partially or entirely removed from each clad on the incident side end face. As a result, the portion on the incident side end face of the bundle fiber that does not contribute to the waveguide of incident light can be reduced, and highly efficient coupling can be achieved.

[0013] In another embodiment, in the bundle fiber, the cladding is removed by chemical etching at each incident side end face of the optical fiber. As a result, the cladding can be removed without applying physical stress to each optical fiber. In addition, since the properties of the surface to be coated are smooth according to chemical etching, the optical characteristics of the remaining core and clad are not deteriorated.

[0014] The above summary of the invention does not enumerate all necessary features of the present invention. Also, a sub-combination of these feature groups can also be an invention.

The invention's effect

[0015] The bundle fiber of the present invention can guide more light at the incident side end face by coupling it to the core. This bundle fiber is easy to manufacture and contributes to cost reduction.

Brief Description of Drawings

FIG. 1 is a cross-sectional view showing a structure of a single holey fiber 100.

FIG. 2 is a side view showing an embodiment of a bundle fiber 200 using a holey fiber 100.

FIG. 3 is a cross-sectional view for explaining processing into a conventional optical fiber 300 used for the bundle fiber 200.

FIG. 4 is a side view showing the structure of a bundle fiber 400 formed of an optical fiber having a clad 320.

Explanation of symbols

[0017] 100 holey fiber,

110 quartz glass part, 112 holes,

120, 330 protective coating,

130 integrated part,

200, 400 Nondolev: Γinoku,

300 optical fiber,

310 cores,

320 clad,

430 Meeting part

BEST MODE FOR CARRYING OUT THE INVENTION

[0018] Hereinafter, embodiments will be described, but the following embodiments do not limit the invention according to the claims. In addition, all the features in each embodiment are not necessarily essential configuration requirements.

[0019] A conventional optical fiber that is widely used has a solid structure in which a region having a high refractive index called a core is provided at the center of quartz glass or the like. On the other hand, as shown in FIG. 1, the holey fiber 100 is provided with a plurality of holes 112 in the axial direction of the fiber, and the central part of the stone glass part 110 is a high refractive index core part. The air layer in the hole 112 is a clad portion having a low refractive index. Since the refractive index difference between air and glass is extremely large, a high numerical aperture can be obtained and more incident light can be guided into the optical fiber. The guiding principle is total reflection at the boundary formed on the outer periphery of the core, as in a conventional optical fiber having a cladding. Although FIG. 1 shows a single layer of holes 112 arranged concentrically with the optical fiber itself, the holes 112 may be provided in multiple layers concentrically, and the cross-sectional shape of the holes 112 The arrangement may not be circular.

[0020] In order to manufacture the holey fiber 100, for example, there are the following methods. First, a porous glass base material is manufactured by depositing glass fine particles generated by a flame hydrolysis reaction of a glass raw material. Next, the obtained porous glass base material is heated at 1100 to 1450 ° C during dehydration treatment or after dehydration treatment as necessary to shrink the porous glass base material to a bulk density suitable for drilling. . In addition, the end face is polished and drilled in the axial direction with a carbide drill, diamond drill, etc., and then dehydrated, purified, and transparentized. Holey fiber Examples of 100 materials include pure quartz glass and quartz glass doped with at least one of fluorine and hydroxyl groups.

[0021] In the case where different cores and glasses are used for the core and the clad as in the conventional optical fiber, the core or the clad is not optimal for guiding light. I had to use it. On the other hand, in the case of holey fiber, only the glass most suitable for the wavelength of the transmitted light can be used. For example, a holey fiber can be formed from quartz glass having a single composition doped with at least one of fluorine and a hydroxyl group, which has excellent ultraviolet resistance when transmitting ultraviolet light.

[0022] In order to manufacture the bundle fiber 200 with the holey fiber 100 as described above, first, the force near the end of the holey fiber 100 and the protective coating 120 are removed, and then in an atmosphere gas or a reduced pressure atmosphere. By heating and collaborating, the pores 112 are crushed into a solid glass fiber. Next, as shown in FIG. 2, the bundled end portions are further heated and melted to form an integral flange portion 130.

[0023] By these steps, the gap between the holey fibers 100 is eliminated. Further, the end face of the integral part 130 is formed of a single composition glass. Here, “collapse” means filling the gap between the optical fibers and the hole 112 of the holey fiber 100 by melting and crushing the bundled optical fibers (holey fiber 100).

[0024] It should be noted that a carbon heater, an oxyhydrogen flame, or the like can be used as a heating means for forming the integral flange 130. Further, by removing the protective coating 120 in the vicinity of the end portion and heating and melting the bundled holey fiber 100, the collapse of the air holes 112 and the integral flange portion 130 can be simultaneously formed.

[0025] Further, according to the present invention, the core filling rate of the bundle fiber can be improved even when the conventional optical fiber 300 is used. As shown in a cross section in FIG. 3, the protective coating 330 is first removed near the end of the light incident end side, and then part or all of the cladding 320 of the optical fiber 300 is removed. Further, the core 310 is melted and integrated in the vicinity of the end. The bundle fiber obtained in this way can increase the core filling factor of the light incident part up to 100%. Such a bundle fiber is formed by using a plurality of conventional optical fibers having a core portion and a clad portion, and a bundle fiber having a core filling rate of 90% or more on the incident side end face. One of Aiba.

[0026] In order to remove a part or all of the cladding 320 in the vicinity of the incident side end face of the optical fiber 300, for example, a method in which the optical fiber 300 is immersed in a hydrofluoric acid solution and chemically etched is used. Can be mentioned. At this time, etching is performed so that the core filling rate at the end face of each optical fiber 300 is 90% or more, preferably 80% or more, and more preferably 100%.

[0027] In addition, in order to obtain a bundle fiber suitable for the transmission of ultraviolet rays, the core is made of pure silica glass or quartz glass doped with at least one of fluorine and a hydroxyl group, and the glass is doped with fluorine. Is preferable.

FIG. 4 is a side view schematically showing the structure of the bundle fiber 400 formed by the optical fiber 300 having the clad 320. As shown in FIG. 3, the optical fiber forming the bundle fiber 400 has the clad 320 removed in the vicinity of the incident end as shown in FIG. Therefore, the incident end of the bundle fiber 400 is formed as an aggregate portion 430 in which the cores 310 of the optical fiber 300 are densely aggregated.

[0029] In this bundle fino 00, the end surface on the incident side should be melted and integrated, but the core filling rate by the core 310 is still 90% or more. Such a bundle fiber is also one of bundle fibers formed by using a plurality of conventional optical fibers having a core part and a clad part, and having a core filling rate of 90% or more on the incident side end face.

Industrial applicability

[0030] In this way, a bundle fiber having a high core filling factor on the incident side end face can be obtained easily and at low cost. A bundle fiber with a high core filling factor can guide much of the incident light, so high V and transmission efficiency can be obtained. When a bundle fiber is produced using an optical fiber made of a quartz material, it can be suitably used for transmitting ultraviolet rays.

Claims

The scope of the claims

[1] A bundle fiber in which a plurality of optical fibers are bundled, and the ratio force area ratio of the material forming the core of the optical fiber on the incident side end face of the guided light is 90% or more and 100% or less Bundle fiber characterized by being.

2. The bundle fiber according to claim 1, wherein the optical fibers are integrated with each other at the incident side end face by melting.

[3] The bundle fiber according to claim 1 or 2, wherein the optical fiber is a holey fiber.

4. The bundle fiber according to claim 3, wherein the incident side end face is formed by the holey fiber having its holes collapsed.

[5] The bundle fiber according to [3] or [4], wherein the material of the holey fiber is pure silica glass.

[6] The fiber strength of the holey fiber according to claim 3 or 4, wherein the fiber is quartz glass doped with at least one of fluorine and a hydroxyl group.

[7] The optical fiber includes pure silica glass or a core made of quartz glass that is doped with at least one of fluorine and a hydroxyl group, and a clad made of quartz glass that is doped with fluorine. The bundle fiber according to Item 2.

[8] The bundle fiber according to [7], wherein a part or all of each clad is removed from each force on the incident side end face of the optical fiber.

9. The bundle fiber according to claim 8, wherein the clad is removed by chemical etching on the incident side end face of each of the optical fibers.