JP2000075162A - Production of fusion stretched optical coupler and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a fusion stretched optical coupler having a production yield of >=90% and having high reliability and an apparatus therefor. SOLUTION: The fusion stretched optical coupler, which is made uniform in optical fiber tension at the time of forming an optical fiber bundle, has the production yield of >=90% and has the high reliability, is produced by fusion stretching the optical fiber bundle by setting the set tension of optical fibers as the time of constituting the optical fiber bundle at a range of 19.5 to 105 MPa and maintaining the tension differences between the respective fibers within 20% of the set tension.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing an optical coupler, and more particularly, to a fusion-stretched optical coupler having a tapered region obtained by fusion-stretching while heating a central portion of an optical fiber bundle. And a device therefor.

[0002]

2. Description of the Related Art With the development of optical fiber transmission technology, optical couplers for multiplexing and splitting light have become increasingly important as optical components for optical fiber communication systems, LANs and various measurement systems.

FIG. 4 is a flowchart of a method for manufacturing a conventional fusion-stretched optical coupler, and FIG. 5 is an external perspective view of the fusion-stretched optical coupler.

In FIG. 4 and FIG. 5, a fusion-stretched optical coupler 1 is provided with an optical fiber treatment by removing coatings 2a and 3a at the center of optical fibers 2 and 3 and removing optical fiber cores 2b and 3a.
b is exposed (Step Sa), and two optical fibers 2 and 3 are set in a manufacturing apparatus not shown (Step Sb),
Optical fiber cores 2b, 3b at the center of optical fibers 2, 3
(Step Sc), and the portion where the optical fibers 2 and 3 are closely adhered is fused and stretched while being heated by a heat source such as a burner (not shown) to form a tapered region 4 (Step S).
d), heating is completed when predetermined optical characteristics are obtained, and the obtained optical fiber coupler body is obtained by bonding and fixing the both ends of the glass tube with an adhesive such as an epoxy resin or an acrylic resin at both ends (step). Se).

[0005] The fusion-stretched optical coupler 1 is such that an optical signal 5 input from one end (left end in the figure) can be output to two optical fibers (right side in the figure).

Here, the characteristics of the optical coupler include excess loss and branch ratio, which are defined by equations (1) and (2), respectively.

[0007]

(Equation 1)

[0008]

(Equation 2)

Here, Pin: input power Pt: output power on the transmission side Pc: output power on the coupling side

[0010]

However, in the conventional method, since the optical fiber tension at the time of forming the optical fiber bundle is not uniform, the production yield is as low as about 70%, and even if the initial characteristics are satisfied, the manufacturing yield remains low. In some cases, the tapered region was disconnected over time due to the influence of stress.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a method and apparatus for manufacturing a fusion-stretched optical coupler having a manufacturing yield of 90% or more and having high reliability.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, a method for manufacturing a fusion-stretched optical coupler according to the present invention comprises the steps of fusion-stretching while heating a central portion of an optical fiber bundle comprising a plurality of optical fibers. In the method for producing an optical fiber coupler having a tapered region obtained by the above method, the set tension of the optical fiber is 1
The optical fiber bundle is configured so as to be in the range of 9.5 to 195 MPa, and the difference in tension between the optical fibers is set to 20 of the set tension.
%.

According to the apparatus for manufacturing a fusion-stretched optical coupler of the present invention, a holding means for holding an optical fiber bundle comprising a plurality of optical fibers, a heating means for heating a central portion of the optical fiber bundle, and a heating means for heating the heating means And a fusion stretching means for forming a tapered region by fusing the drawn optical fiber bundle to form a tapered region, wherein the set tension of the optical fiber when forming the optical fiber bundle is 19.5 to 195 MPa. And the difference in tension between the optical fibers is 20% of the set tension.
% Or less, and a tension applying device for performing fusion-stretching.

According to the present invention, the set tension of the optical fibers when forming the optical fiber bundle is set in the range of 19.5 to 195 MPa, and the difference in tension between the optical fibers is set to the set tension of 20 MPa.
%, The optical fiber tension at the time of forming the optical fiber bundle becomes uniform, the production yield is 90% or more, and a highly reliable method for producing a fusion-stretched optical coupler and its apparatus. Offer can be realized.

[0015]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a flow chart showing one embodiment of a method for producing a fusion-stretched optical coupler according to the present invention. Note that the same members as those in the conventional example shown in FIG.

As an optical fiber treatment, the coatings 2a and 3a at the central portions of the optical fibers 2 and 3 are removed, and
b and 3b are exposed (step S1).

The optical fibers 2 and 3 from which the coatings 2a and 3a at the center have been removed are set in the apparatus for manufacturing a fusion-stretched optical coupler (step S2).

Tension is applied to the set optical fibers 2 and 3 by a tension applying device (step S3).

The central portions of the optical fibers 2 and 3 are brought into close contact (step S4).

The optical fibers 2 and 3 are fused and drawn while being heated by a heat source such as a burner (not shown) to form the tapered region 4 to form the optical coupler 1 (step S5).

Heating is completed when predetermined optical characteristics are obtained, and the obtained optical fiber coupler body is adhered and fixed at both ends of the glass tube with an adhesive such as epoxy resin or acrylic resin to reinforce the optical coupler 1 (step). S6).

The set tension of the optical fiber bundle is 19.5-19
As a result of performing the fusion-stretching while setting the tension difference between the optical fibers within the range of 5 MPa and the tension difference between the optical fibers within 20% of the set tension, the production yield was as good as 90% or more.

As a method for applying tension to the optical fiber, there is a method using a tension applying device shown in FIG.

FIG. 2 is an external perspective view of a tension applying device used in the apparatus for manufacturing a fusion-stretched optical coupler of the present invention.

This tension applying device is provided on a base 31, a clamp 32 provided on the base 31, a slide stage 33 provided on the base 31 in opposition to the clamp 32, and provided on the clamp 32. An optical fiber holder 34 for holding one end of the optical fiber 2;
A clamp 35 provided above, an optical fiber press 36 provided on the clamp 35 for pressing the other end of the optical fiber 2, one end is fixed and the other end is connected to the clamp 35 to apply tension to the optical fiber 2. Spring 3 to do
7.

This tension applying device has one side (left side in the figure).
Are fixed, and the other (right side in the figure) uses optical fiber holding clamps 32 and 35 fixed to the slide stage 33, and tension is applied to the optical fiber 2 by the slide stage 33 and the spring 37. By using such a tension applying device, a uniform tension is applied to the optical fiber bundle.

A burner (not shown) as a heating means is provided on a table 31 of the tension applying device, and a plurality of optical fibers are held by clamps 32 and 35 as holding means. The optical fiber bundle is configured to be in the range of 5 to 195 MPa, and the tension is fixed so that the tension difference between the optical fibers is within 20% of the set tension. By forming a tapered region by fusing and stretching with the above slide stage, it is possible to obtain a highly reliable fused and stretched optical coupler with a manufacturing yield of 90% or more.

FIG. 3 is an external perspective view showing a modification of the tension applying device.

The difference from the tension applying device shown in FIG.
The point is that a weight 38 is used instead of a spring for applying tension. Even with such a tension applying device, a uniform tension is applied to the optical fiber bundle, and the manufacturing yield is 90%.
As described above, a highly reliable fusion-stretched optical coupler can be obtained.

[0031]

Next, the reason for limiting the tension range to 19.5 to 195 MPa will be described together with the examples.

Using a single mode fiber having an outer diameter of about 80 μm, the optical fiber tension is set to 0, 5, 10, 20, 5
0, 80, 100, 120, and 140 g, each 1
00 2 × 2 optical couplers were manufactured and the manufacturing yield was investigated. An optical coupler having an excess loss of 0.5 dB or less and a branching ratio of 40 to 60% or less is defined as a good product. As a result, the production yield was a tension of 0 g: 20.
%, 5 g: 70%, 10 g: 90%, 20 g: 93%,
50 g: 95%, 80 g: 93%, 100 g: 93%,
120 g: 80% and 140 g: 30%. When the tension is low, 0 g and 5 g often cause the two fibers to be stretched without being integrated, and when the tension is high, 120 g and 140 g, the optical fiber may break at the moment when the optical fiber is heated. Many have led to lower yields, respectively. Therefore, the yield of 90% or more can be secured in the range of 10 to 100 g, that is, 19.5 to 195.
It can be said that MPa is optimal.

The reason for limiting the variation in tension is that the set tension of one optical fiber is fixed at 50 g in a 2 × 2 optical coupler of a single mode fiber having an optical fiber outer diameter of 80 μm, as described above. Set the tension of the other optical fiber to 30, 35, 40, 45, 50,
100 optical couplers were manufactured at 55, 60, 65, and 70 g each, and the manufacturing yield was investigated. The range of conforming products was the same as described above. As a result, the production yield is such that the other tension is 30%.
g: 40%, 35 g: 85%, 40 g: 92%, 45
g: 93%, 50 g: 95%, 55 g: 92%, 60
g: 91%, 65 g: 70%, 70 g: 30%. When the optical fiber was heated, the optical fiber was bent at the moment when the optical fiber was heated, and in many cases the optical fiber was not integrated or disconnected in the process of fusing and stretching. Further, the manufactured optical coupler is
A heat shock test was performed at 0 ° C. to 80 ° C. for 100 cycles.
Approximately 20% of the wires were disconnected from those of 5 g. However, 40g ~
There was no disconnection in the 60 g one. Therefore, it can be said that the optimal variation of the tension of the optical fiber bundle is 40 g to 60 g, that is, the set tension error is within 20%.

As described above, according to the present invention, a production yield can be improved, and a fusion drawn optical coupler having stable mechanical strength and characteristics over a long period of time can be obtained.

As specific long-term test results, a heat shock test of −40 ° C. to 80 ° C., 8 hours / cycle, and a heat shock test of −40 ° C. to 80 ° C., 2 hours / cycle, 3000 cycles each were performed for 100 vehicles. There was no disconnection, and the change in excess loss was within 0.1 dB and the change in branching ratio was within 2%.

[0036]

In summary, according to the present invention, the following excellent effects are exhibited.

It is possible to provide a method and apparatus for manufacturing a fusion-stretched optical coupler having a manufacturing yield of 90% or more and a high reliability.

[Brief description of the drawings]

FIG. 1 is a flowchart showing one embodiment of a method for manufacturing a fusion-stretched optical coupler of the present invention.

FIG. 2 is an external perspective view of a tension applying device used in a manufacturing apparatus for a fusion-stretched optical coupler of the present invention.

FIG. 3 is an external perspective view showing a modification of the tension applying device.

FIG. 4 is a flowchart of a conventional method for manufacturing a fusion-stretched optical coupler.

FIG. 5 is an external perspective view of a fusion-stretched optical coupler.

[Explanation of symbols]

 31 units 32, 35 Clamp 33 Slide stage 34, 36 Optical fiber holder 37 Spring

Claims (2)

[Claims] 1. A method of manufacturing an optical fiber coupler having a tapered region obtained by fusing and stretching a central portion of an optical fiber bundle comprising a plurality of optical fibers while heating the optical fiber bundle. A fusion-stretched optical coupler, wherein the optical fiber bundle is configured to be in a range of 0.5 to 195 MPa, and fusion-stretched so that a difference in tension between the optical fibers is within 20% of a set tension. Manufacturing method. 2. A holding means for holding an optical fiber bundle composed of a plurality of optical fibers, a heating means for heating a central portion of the optical fiber bundle, and an optical fiber bundle heated by the heating means being fused and drawn. An optical fiber coupler manufacturing apparatus having a fusion-stretching means for forming a tapered region by setting a set tension of the optical fiber when forming the optical fiber bundle to 1
An apparatus for manufacturing a fusion-stretched optical coupler, comprising: a tension-applying device in a range of 9.5 to 195 MPa, wherein a tension difference between the optical fibers is within 20% of a set tension, for performing fusion-stretching.