JPH0477286B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical branching device for branching transmitted optical signals in a signal transmission system using optical fibers as transmission paths.

Conventional configurations and their problems In recent years, optical fiber transmission has been put into practical use, and is being applied not only to general communications but also to relatively simple signal transmission in the fields of consumer and industrial equipment. As one of the optical components suitable for such an optical fiber transmission system, an optical branching device for branching optical signals is considered to be useful.

Hereinafter, the conventional optical splitter as described above will be explained with reference to the drawings.

A typical configuration of a conventional optical splitter is shown in FIG.

In Figure 1, 1 is an optical fiber for inputting light into a splitter 2, 3 is its core, 2 is an optical splitter, and one tip of the two optical fibers 4 and 5 is gradually polished. and then come into close contact with each other at position 6,
At the light incident end position 7, the core diameter is the same as that of the optical fiber 1.

The operation of the optical splitter configured as above will be explained. First, the light 8 emitted from the optical fiber 1 enters the input end 7 of the optical splitter 2 . The incident light passes through position 6 and gradually connects to two optical fibers 4.
and 5, the light beams branch out and proceed, resulting in the branched lights 9 and 10.

However, the above-mentioned configuration has the disadvantage that mass production is poor because the production of the optical splitter 2 involves the difficult work of polishing the optical fibers 4 and 5. moreover,
In this configuration, the branching ratio at which the light emitted from the optical fiber 1 is branched into the optical fibers 4 and 5 is uniquely determined by the amount of polishing at the position 6 of the optical fibers 4 and 5, so any branching ratio can be set. Cannot be changed.

Furthermore, since polishing has poor reproducibility, it has drawbacks such as variations in branching characteristics.

OBJECT OF THE INVENTION In view of the drawbacks of the conventional example, the object of the present invention is to provide simple optical fiber transmission for use in the consumer and industrial equipment fields, and to be able to arbitrarily vary the branching ratio and eliminate the need for polishing of the optical fiber. The object of the present invention is to provide an optical splitter that can be easily mass-produced.

Structure of the Invention The optical branching device of the present invention includes an optical branching section that collects one end of each of two optical fibers and uses it as a light input end;
It is composed of another optical fiber for inputting light into this input end.

An optical branching section is an abbreviation that is made by heating one end of a plastic optical fiber with a relatively large core diameter and a thin cladding part, gradually deforming it, and maintaining the radius and cross-sectional area of the original optical fiber at the end face. Two semicircular optical fibers are formed by heating and deforming the surfaces thereof in close contact with each other so that the outer shape of the tip part becomes a substantially oval shape having the radius of the original optical fiber. Furthermore, another optical fiber is provided to allow light to enter from this oval end face, and the light output end face of this optical fiber can be moved in the longitudinal direction of the approximately oval end face perpendicular to the direction in which the light travels. The light branching ratio can be arbitrarily varied according to the amount of movement.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows the configuration of a typical optical splitter according to the present invention. In FIG. 2, reference numeral 11 denotes an optical fiber that allows light to travel in the direction of arrow 12, such as a plastic optical fiber with a large core diameter and a thin cladding; 13 and 14 the core and cladding of the optical fiber 11;
1 is a holding fitting for the optical fiber 11, and 16 is a light emitting end face. Numerals 17 and 18 are plastic optical fibers having the same core diameter as the optical fiber 11, and constitute a branch portion 19. 20, 21 and 2
2 and 23 are the core portion and cladding portion of the optical fibers 17 and 18, respectively; 24 is the input end surface that makes the light 12 emitted from the optical fiber 11 enter the branching portion 19; and the end surface 24 is the deformation of the optical fibers 17 and 18 near the end surface. They are brought into close contact with each other at the boundary 25 to form a substantially oval shape as shown in the figure. 26 is a holding fitting for optical fibers 17 and 18; 27 and 2;
8 indicates light propagating in optical fibers 17 and 18, respectively.

The configuration of the branching section 19 will be explained in more detail. FIG. 3 is an explanatory diagram of the branching section 19. Here, 18 is a plastic optical fiber, 21, 23
2 are a core portion and a cladding portion, respectively, and 26 is a metal fitting for holding and deforming the optical fiber 18.

First, in FIG. 1A, the tip 29 of the optical fiber 18 fixed to the metal fitting 26 is heated to soften it
The optical fiber 18 is crushed to the position of the surface 30 and deformed into a substantially semicircular shape while maintaining the radius and cross-sectional area of the optical fiber 18 at the tip end surface 31, as shown in the end view of the optical fiber in FIG. 3B. That is, the area of the portion shown at 32 is transformed to come to positions 33 and 34.

A groove for deforming the optical fiber 18 is cut in the metal fitting 26 in advance. The two optical fibers produced by heating and deforming in this way are brought into close contact with each other at the surface 30, and the end surface 2 is formed as shown in FIG. 3c.
4 is fixed in a substantially oval shape having the radius of the original optical fiber and the cross-sectional area of the two optical fibers, thereby forming the branch portion 19.

Returning again to the embodiment shown in FIG. 2, the explanation will be continued.

The optical fiber 11 through which light enters the branch portion 19 is perpendicular to the direction of the arrow 35, that is, the direction in which the light travels, and is movably held in the longitudinal direction of the substantially oval end face 24. Note that the end surface 24 and the end surface 16 are almost close to each other and face each other.

The operation of the optical splitter configured as described above will be explained below. End face 16 of optical fiber 11
The light 12 emitted from the branch section 19 enters the end face 24 and enters each of the optical fibers 17 and 18. The operation at this time will be explained using FIG. 4. FIG. 4 shows a coupling surface between the input end surface 24 of the splitting section 19 and the output end surface 16 of the optical fiber 11. In the same figure a, when the output end face 16 of the optical fiber 11 is located at the center of the input end face 24 of the branch part 19, the input end face 24
Approximately 50% of the light incident through the optical fibers 17 and 18 is split into each of the optical fibers 17 and 18 and propagated therein, so that the branching ratio is 1:1. Next, as shown in FIG. 4B, when the output end face 16 is shifted from the position of the boundary 25 of the input end face 24 and coupled, the light enters the optical fibers 17 and 18 according to the amount of shift. Incidence end surface 2
4, the ratio of the amount of incident light, that is, the branching ratio changes.

As described above, according to this embodiment, since the optical splitter is constituted by an optical fiber that has been deformed by heating, mass productivity is better than in the conventional example which requires polishing work. Furthermore, by changing the coupling position between the input end face 24 of the branching part 19 and the output end face 16 of the optical fiber 11 that makes light enter the branching part 19,
This has the effect of allowing the light branching ratio to be changed arbitrarily.

In the embodiments of the present invention, the optical fiber has been described using a plastic optical fiber having a relatively large core diameter, but any optical fiber may be used as long as it can be heated and deformed. Moreover, although the holding metal fittings were used to thermally deform the optical fiber, any other means may be used. Furthermore, a close contact portion (boundary) 25 of the two optical fibers 17 and 18 that constitute the branch portion 19
If plastic optical fibers with thin cladding parts are used, the cladding parts may be left in close contact with each other without being removed; however, in the case of other optical fibers, the cladding parts in the contacting parts may be removed by polishing or the like. Also good. Further, in this embodiment, in order to vary the branching ratio, the optical fiber 11 for making light enter the branching part 19 is held movably, but the entrance surface 24 of the branching part 19 or both may be moved. It may be kept at

Effects of the Invention According to the present invention, by preparing an optical fiber having a deformed end face and one optical fiber, an optical splitter having an arbitrary branching ratio can be manufactured. That is, the deformed end face is formed by abutting the radial portions of two optical fibers, each of which is an ellipse having the diameter of one optical fiber before deformation, at one end, and a different optical fiber is formed on the deformed end face. By moving the fiber in the longitudinal direction, an optical fiber with an arbitrary branching ratio can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional optical branching device, FIG. 2 is an explanatory diagram of an optical branching device according to an embodiment of the present invention, FIG. 3 is an explanatory diagram of the optical branching section in FIG. 2, and FIG. The figure is the second
FIG. 3 is an explanatory diagram of a coupling surface of the optical splitter shown in the figure. 11, 17, 18...optical fiber, 12, 2
7, 28...Arrow representing light, 13, 20, 21
... core part, 14, 22, 23 ... clad part,
15, 26... Holding metal fitting, 16... Light output end face, 19... Light branching section, 24, 31... Light incidence end face, 25, 30... Optical fiber contact surface/boundary, 29... Light Fiber tip, 35...arrow indicating direction of movement.

Claims (1)

[Claims] 1. One end of each of the two optical fibers is used as a light output end, and the other ends of the two optical fibers are brought together,
The outer shape of the collective end surface is such that it has a radius portion of the optical fibers in the center and approximately 2 points at the ends of the optical fibers.
One optical fiber is deformed into a substantially oval shape having twice the cross-sectional area and optically coupled to the deformed end face, and the end face of the one optical fiber and the collective end face are connected in the longitudinal direction of the collective end face. An optical branching device characterized in that it is optically coupled in a movable manner relative to the optical branching device.