JPH0721570B2 - Optical distribution circuit and manufacturing method thereof - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an optical distribution circuit for distributing an optical beam transmitted through an optical fiber to a plurality of optical fibers and a method for manufacturing the same.

[Background of the Invention]

Along with the rapid progress of optical fiber transmission technology, research and development of optical data links using optical fibers for data transmission between computers and computers and between computers and terminals have been actively conducted. In configuring this optical data link,
An optical star coupler capable of mixing optical signals from a plurality of input optical fibers and evenly distributing them to a plurality of output optical fibers with low loss is an essential device.

Conventionally, there is a biconical taper type shown in FIG. 7 as a typical example of an optical star coupler (published by Hisashiyoshi Yanai, "Optical Communication Handbook", Asakura Shoten, September 1, 1982, first edition, first edition 324).
~ Page 325). This is because a large number of optical fibers 1 are put together at one place, twisted while being heated and fused, and a tapered region 5 is formed in the central portion of the optical fiber 1 for input (the tapered region 5 The optical signal from the left side) is distributed to a plurality of output optical fibers (right side of the tapered region 5). In addition, in FIG. 7, the arrow indicates the traveling direction of the optical signal. As a heating source for this optical fiber,
An oxyhydrogen burner and an electric furnace are used. The method using the oxyhydrogen burner can raise and lower the temperature very easily, so the work can be completed in a short time, but the shape of the twisting, fusion, and extension part is deformed due to the wind pressure of the burner, flame temperature, disturbance, etc. Easy to do. That is, it is almost impossible to control the shape of the above-mentioned twist, fusion, and stretched portions, the yield is very poor, and there are problems in reproducibility and mass productivity. The method using an electric furnace can suppress the above-mentioned disturbance, but since the temperature rise and fall is extremely slow, there is a problem that the optical fiber is deformed excessively during the temperature rise and fall. As described above, it is difficult to produce good optical characteristics with good yield by the conventional method. Further, since the yield becomes very bad, it is difficult to reduce the cost.

The present inventor has previously proposed the optical distribution circuit of FIG. 6 as one method for solving the above problems. This is a fiber optic bundle
1a and 1b are inserted into a hollow glass tube 8 to form twisted portions 6a and 6b, and the glass tube 8 is heated by an oxyhydrogen burner, so that the twisting / fusion / stretching portion 7 is made into a glass by an indirect heating method. It is formed in the pipe. Then, both ends of the glass tube are sealed with an adhesive 9 or the like to fix the optical fiber bundles 1a and 1b and the glass tube 8. Since this structure can be manufactured by an integrated process, cost reduction can be expected. Further, since it is an indirect heating method of the optical fiber bundle, the optical fiber bundle is not excessively deformed by the wind pressure of the burner, flame, disturbance, etc.
The shape controllability of twisting, fusion, and stretching is extremely good. Impurities that cause absorption loss such as a large amount of water and transition metal ions contained in the flame of the burner are not diffused and penetrated into the optical fiber, resulting in low insertion loss. In addition, since the shape controllability is good, it has a feature that the variation (distribution variation) of the optical output of each output port fiber can be suppressed to an extremely small level. By the way, as shown in FIG. 1, the output port fibers 30- of the two optical distribution circuits 33, 34
3 and input port fiber 31-1 are connected in cascade (connection part 32)
Such a configuration is about to be used in various systems. In that case, if an attempt is made to use two optical distribution circuits as shown in FIG. 6, a connection loss occurs at the connection section 32, and the overall loss increases. If the connection is to be made by the heat fusion method, the length of the fibers 30-3 and 31-1 must be made sufficiently long, the loss increases accordingly, and the size of the optical distribution circuit also increases. growing. Further, since an extra process such as heat fusion work is added, the cost becomes high. As described above, it has been found that there are various problems when the individually formed optical distribution circuits are combined.

[Object of the Invention]

An object of the present invention is to solve the above problems and provide a low loss, small size, low cost integrated optical distribution circuit and a manufacturing method thereof.

[Outline of Invention]

The present invention is formed by juxtaposing two optical distribution circuits each having a twisted portion and a twisted / fused / extended portion of an optical fiber bundle composed of n optical fibers in a container. Is composed of one optical fiber having no common connecting portion between the two optical fiber bundles, and n optical fiber ends are provided on one end side of each container,
An optical distribution circuit in which n-1 optical fiber ends are located on the opposite end side, two containers are juxtaposed, and an optical fiber bundle consisting of n optical fibers is inserted into the two containers. At this time, one optical fiber is included in the two optical fiber bundles in a common state without being connected, and n optical fiber ends are provided on one end side of the respective containers, A step of bringing n-1 optical fiber ends to the opposite end side, a step of twisting the optical fiber bundle, a step of heating the container to twist / fuse / stretch the optical fiber bundle in the container. It is a method of manufacturing an optical distribution circuit, which comprises a step of adding and a step of sealing both ends of the container with an adhesive to fix the container and the optical fiber bundle.

Example of Invention

FIG. 2 shows an embodiment of the optical distribution circuit of the present invention. This is an embodiment in which the cascaded optical distribution circuit of FIG. 1 is constructed in an integrated structure, and there is no connecting portion 32 of FIG. That is, 30-1,51,31
-3 is composed of one optical fiber, as will be described later. The size is apparently small as it is configured in parallel, and the input / output ports 30-1, 30-2, 31-3, 31-4, 30-4,
Since 31-2 is arranged on the left and right, connection with other devices is easy. The structures of the twisting / fusing / extending portion and the twisting portion formed in the glass tubes 35 and 36 are the same as those in FIG.

FIG. 3 shows a method of manufacturing the optical distribution circuit of FIG. It consists of four processes. First, in (a), the optical fibers 51, 5 are placed in the glass tubes 35, 36 (for example, quartz glass tubes).
The process of inserting 2,53. The optical fiber 52 is inserted into the glass tubes 35 and 36. The glass tubes 35 and 36 are juxtaposed. Next, in (b), the input port fiber 30-
The optical signal Pi ₁ is input from 4 and the output port fiber 30-
No. 6 in the glass tube 35 while monitoring the optical output of 1,30-2
The twisted portion and the twisted / fused / stretched portion are formed by the same method as shown in the figure. Then, when the optical outputs of 30-1 and 30-2 become equal, the process of (b) is finished. Next, in (c), an optical signal Pi ₂ is made incident from the input port fiber 31-2, and a twisted portion and a twisted portion are formed in the same manner as in (b) above.
Manufactures fusion / stretching parts. Finally, in (d), both ends of the glass tube are sealed with the adhesive 9. Glass tube 3
5,36 may be filled with a high molecular weight polymer for absorbing mechanical vibration and impact. Further, the above processes (b) and (c) may be performed simultaneously.

FIG. 4 shows an embodiment of the optical distribution circuit manufacturing apparatus of the present invention. First, the parts will be explained. 39 is a laser light source (for example, He-Ne laser), which is an optical fiber for dummy
Input port fiber through 40-1, 40-2 30-4, 31-2
Light is injected into the interior. 41 is a connector. Reference numeral 42 is a base for fixing the optical fibers 31-2, 30-4, and 52, and 43-1 and 43-2 are fixing jigs thereof. 44-1, 44-2 are glass tube fixing bases. 45 is an installation base of the oxyhydrogen burner 15, which has a mechanism capable of moving in the direction of arrow 46. 47-1, 47-2 is a mechanism for fixing the optical fiber bundle and the above-mentioned optical fiber bundle is indicated by arrows 48-1,
It is equipped with a rotating mechanism that twists the optical fiber bundle by rotating it in the 48-2 direction. 49-1, 49-2 is the above 47-
It is a mechanism that moves 1,47-2 in the directions of arrows 50-1,50-2. 38 is the base. This equipment first heats the glass tube 35 to create a light distribution circuit, and then connects the oxyhydrogen burner 15 with an arrow.
It is a device that moves in the 46 direction and heats the glass tube 36 to make a light distribution circuit. However, with another oxyhydrogen burner,
If the laser light is made to enter the input port fibers 30-4 and 31-2 at the same time, the optical fiber bundle can be twisted, fused and stretched at the same time.

The present invention is not limited to the above embodiment. For example, as shown in FIG. 5, the present invention can be applied to a configuration in which n × n port type optical distribution circuits 59 and 60 having n input / output port fibers are connected in cascade.
In this case, 55-1, 56-1 and 58-1 consist of one common optical fiber. The number of ports of the optical distribution circuits 59 and 60 may be different. The material of the optical fiber may be a multi-component type or a plastic fiber other than the quartz type. As the glass tube, other than the quartz tube, a Vycor glass tube, a multi-component glass tube, or the like can be used, which may be selected depending on the material of the optical fiber used. Further, it can be applied to a configuration in which three or more light distribution circuits are connected in cascade.

〔The invention's effect〕

According to the present invention, a low-loss, small-sized integrated optical distribution circuit can be configured. Further, in the conventional method, the optical distribution circuits had to be spliced together by a heat fusion technique or the like, but this configuration does not require such work, and since it is possible to make them in a consistent process or at the same time, Expect mass production at a cost.

[Brief description of drawings]

1 and 5 are block diagrams of cascaded optical distribution circuits, FIG. 2 is an embodiment of the optical distribution circuit of the present invention, and FIG. 3 is an embodiment of a method of manufacturing the optical distribution circuit of the present invention. , FIG. 4 is an embodiment of an apparatus for manufacturing the optical distribution circuit of the present invention, FIG. 6 is a schematic view of the optical distribution circuit previously proposed by the present inventor, and FIG. 7 is a schematic view of a conventional optical distribution circuit. is there. Explanation of symbols 1,1a, 1b, 30-1 to 30-4,31-1 to 31-4,51,40-1,40-
2,55-1 to 55-n, 56-1 to 56-n, 57-2 to 57-n, 58-1
〜58-n …… optical fiber, 6a, 6b …… twisted part, 5,7 ……
Twist / fusion / extension part, 8,35,36 …… glass tube, 9 …… adhesive, 15 …… burner, moving mechanism, 33,34,59,60 …… light distribution circuit, 39 …… light source, 41 ... Connector, 42 ... Optical fiber fixing base, 43-1, 43-2 ... Optical fiber fixing jig, 44-
1,44-2 …… Glass tube fixing base, 45 …… Burner installation base, 47
-1,47-2 ...... Fixed mechanism and rotation mechanism of optical fiber bundle, 49-1,49-2 ...... Axial movement mechanism, 61,62
...... Optical mixing section.

Claims (2)

[Claims] 1. An optical fiber bundle comprising n optical fibers, wherein two optical distribution circuits each having a twist portion and a twist / fusion / extension portion are juxtaposed in a container. One of the optical fibers is composed of one optical fiber having no common connecting portion between the two optical fiber bundles, and n optical fiber ends are provided on one end side of each container.
An optical distribution circuit having n-1 optical fiber ends on the opposite end side. 2. Two containers are juxtaposed, and n is placed in the two containers.
When an optical fiber bundle consisting of two optical fibers is inserted, the two optical fiber bundles are configured so that one optical fiber is included in a common state without being connected, and A step in which n optical fiber ends are provided on one end side and n-1 optical fiber ends are provided on the opposite end side; a twisting step is applied to the optical fiber bundle; A method of manufacturing an optical distribution circuit, comprising the steps of twisting, fusing, and stretching an optical fiber bundle, and sealing both ends of the container with an adhesive to fix the container and the optical fiber bundle.