JPS6348506A - Optical branching tool for optical fiber - Google Patents

Abstract

PURPOSE:To mass-produce articles of accurate size by molding an optical transmission branch line out of a transparent material, supporting both its end parts on a casing through supporting bodies made of other transparent materials with a low refractive index, and placing the remaining part in air in a noncontact state. CONSTITUTION:The supporting bodies 2 made of the transparent materials which have the lower refractive index than the transparent material of the optical transmission branch line 1 are mounted on both end parts of the optical transmission branch path 1 molded branching off into plural optical transmission lines. Those supporting bodies 2 are molded by fitting tubular moldings onto the end parts of the optical transmission lines 1a and 1b or placing them in molds. The optical transmission branch line 1 is supported at the supporting bodies 2 by being clamped with two split casings 3 and 3 from above and below, and the intermediate part of the optical transmission branch line 1 which is not supported by the supporting body couple 2 is held in air in the noncontact state. The air layer is inevitably lower in refractive index than the transparent material of the optical transmission branch line, so the air layer itself serves as a clad to branch light with small light transmission loss. Consequently, transmission lines of accurate size can be mass-produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an optical branching tool used as a connecting tool when branching an optical transmission line of an optical fiber into two or more.

[Prior art]

In general, optical fibers, whether made of quartz or plastic, have a structure in which the outer periphery of an optical transmission path made of a transparent material is covered with a cladding made of a transparent material with a lower refractive index. This is so that the transmitted light is reflected at the boundary with the cladding, reducing light transmission loss. Therefore, an optical branching device for branching an optical fiber optical transmission line into two or more is also required to have a similar configuration.

Conventionally, as the above-mentioned optical branching device, by masking a part and performing photopolymerization, a difference in the degree of polymerization is given partially, and the part with a high degree of polymerization and a high refractive index is used as an optical transmission path, and a refractive index with a low degree of polymerization is used. There is one in which the lower part is molded into a craft.

However, this method is unsuitable for mass production because it tends to cause variations in the degree of polymerization and boundaries, so when mass-produced, the dimensions of each product vary.

[Purpose of the invention]

An object of the present invention is to provide an optical branching device for optical fibers that is easy to manufacture and can be mass-produced with precisely uniform dimensions.

[Structure of the invention]

The optical branching device of the present invention which achieves the above object has a light transmission branch path branched into two or more formed of a transparent material, and at least both ends of the light transmission branch path are formed with a refractive index lower than that of the transparent material. It is characterized in that it is supported on the casing via a support made of another transparent material, and the other parts are kept out of contact with the air.

The transparent material for forming the optical transmission branch in the present invention is preferably a resin such as polymethyl methacrylate (refractive index -1.49), and the transparent material constituting the support is, for example, Fluorine-containing resins such as polytetrafluoroethylene (refractive index = 1°41) are suitable.

〔Example〕

1 to 3 show an optical fiber branching device according to an embodiment of the present invention, in which 1 is molded from a transparent material so that one optical transmission line 1a is branched into two optical transmission lines 1b and 1b. This is an optical transmission branch. This branched optical transmission line 1b
The number of branches is not limited to two, but may be three or more, and the form of branching is not limited to one:multiple branches, but may be multiple:multiple branches. That is, in the first and second embodiments, only one optical transmission line 1a is provided, but a plurality of optical transmission lines 1a may be provided.

At both ends of the optical transmission branch line 1 formed by branching into a plurality of optical transmission lines, there is a respective optical transmission branch line 1.
A support 2 made of a transparent material whose refractive index is lower than that of the transparent material is attached. As shown in FIG. 4, this support body 2 is formed into a tube shape and is used as the optical transmission path 1a.

It may be fitted into the end of 1b, or it may be attached to a mold and molded.

The optical transmission branch l having the support 2 attached thereto in this manner is supported by being sandwiched between the two halves of the casing 3.3 from above and below by the support 2. In this supported state, the intermediate portion of the optical transmission branch 1 that is not supported by the support pair 2 is held in the air in a non-contact state. The material of the casing 3 is not particularly limited, and may be, for example, resin or metal, and does not need to be transparent.

According to the optical branching device configured as described above, most of the optical transmission branch 10 remains exposed to the air layer, but the air layer necessarily has a lower refractive index than the transparent material of the optical transmission branch. Therefore, the air layer itself acts as a cladding and can branch light with little light transmission loss.

In addition, since most of the optical transmission branching path is not covered with a special material, manufacturing of this optical branching device is easy because all that is required is to accurately mold only the optical transmission branching path. and can be mass-produced with accurate dimensions.

〔Effect of the invention〕

As described above, in the present invention, an optical transmission branch path that is branched into two or more is formed of a transparent material, and at least both ends of this optical transmission branch path are formed of another transparent material having a refractive index lower than that of the transparent material. Since it is supported on the casing via a support body and the other parts are kept out of contact with the air, it can be easily manufactured and one product with accurate dimensions can be produced.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional plan view of an optical fiber branching device according to an embodiment of the present invention, FIG. 2 is a side view of the same, and FIG.
The figure is a view taken in the direction of the ■ arrow in FIG. 2, and FIG. 4 is an explanatory diagram showing an exploded view of the optical transmission branch and the support body in the optical branching device. DESCRIPTION OF SYMBOLS 1... Optical transmission branch line, la, lb... Optical transmission line, 2... Support body, 3... Casing.

Claims (1)

[Claims] A light transmission branch branched into two or more is molded with a transparent material,
At least both ends of this optical transmission branch path are supported on the casing via a support made of another transparent material having a lower refractive index than the transparent material, and the other portion is kept in a non-contact state in the air. Features: Optical branching device for optical fibers.