JPH02114213A - Manufacturing method of fiber coupler - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of manufacturing a fiber coupler for branching or merging propagating light within an optical fiber, and particularly relates to a process of fusing and stretching a plurality of optical fibers. The present invention relates to a manufacturing method comprising:

[Conventional technology]

Fiber-type couplers have the function of branching/combining light of a single wavelength or splitting/combining light of multiple wavelengths, and the manufacturing methods include the fusion drawing method in which fibers are fused together and stretched. There is a polishing method in which two fibers with polished side surfaces are placed facing each other.

FIG. 4 shows a method for manufacturing a fiber coupler according to the prior art (
ELECT
RONIC3LETTER815th March 1
984 Vot.

20 No. 8). A fiber coupler using, for example, a single mode fiber will be described below.

First, the coatings of two optical fibers are partially removed and the optical fibers are brought into close contact with each other (step 101). Next, by heating with a burner or the like, this part is fused into a horizontal line, and then stretched in the optical axis direction (step 10
2). In this case, the optical branching ratio is detected by measuring the light incident from one end of the optical fiber at the other end (step 103). When a predetermined branching ratio is obtained, the stretching of the optical fiber is stopped and a coupler member is formed (step 104). Next, this coupler piece is fixed and adhered to a protective member to form a fiber coupler (step 1).
05).

In addition, as another conventional technique, there is a method in which two optical fibers are heated and stretched in a twisted state without being fused or stretched. A study of a method for manufacturing a piconical taper type optical splitter).

[Problem to be solved by the invention]

All fiber couplers according to the prior art are fixed to a protective member with an adhesive or the like, but after stretching, the outer diameter of the thinned coupler portion is less than 20 μm, which is approximately 10 μm of the outer diameter before stretching. It's almost 1/1.

Therefore, the tensile strength at the coupler part decreases significantly,
The wire may break due to heat cycle.

As described above, the fiber type coupler according to the prior art has a drawback of poor reliability when used in an environment where heat cycles are applied.

Therefore, the present invention provides a method for manufacturing a fiber coupler with less disconnection in an environment where the temperature changes.
The purpose is to improve the reliability of fiber couplers.

[Means to solve the problem]

In order to achieve the above-mentioned problems, a method for manufacturing a fiber coupler according to the present invention includes a first method for forming a coupler member by stretching at least two uncoated optical fibers in the optical axis direction while fusing them. a second step of applying a predetermined tension to the coupler member in the optical axis direction and inspecting the coupler member for breakage; and fixing the coupler member without breakage to the protection member. The method includes a third step of forming a fiber coupler.

[Effect]

Since the present invention is configured as described above, the optical fiber fixed to the protection member can have a higher breaking strength than the tension acting on the fiber coupler due to temperature change.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a fiber coupler according to an embodiment of the present invention will be described below with reference to the accompanying drawings. In the description, the same elements are denoted by the same reference numerals, and redundant description will be omitted.

FIG. 1 is a process diagram showing a process for manufacturing a fiber coupler according to an embodiment of the present invention, and FIG. 2 is a flow chart showing a method for manufacturing a fiber coupler.

In step 201, part of the coating of the optical fiber core wire 1.2 is removed, and the optical fibers 1a and 2a from which the coating has been removed are placed in close contact with each other (see FIG. 2(a)).

In step 202, the adhering portion is fused using a heating device 3 such as a burner and stretched in the optical axis direction (FIG. 2(b)).
reference).

In step 203, in the process of fusing and stretching,
The optical branching ratio is detected by measuring the light incident from one end of the optical fiber at the other end.

In step 204, when a predetermined branching ratio is obtained, the stretching and fusing of the optical fiber is stopped, and a coupler member including the coupler portion A is formed (see FIG. 2(C)).

In step 205, a predetermined tension is applied to the coupler member in the direction of the optical axis, and the presence or absence of breakage of the coupler member is inspected (see FIG. 3(d)).

In step 206, only the coupler members that were not broken as a result of the above inspection are fixed to the protective member 4 with an adhesive such as epoxy resin or ultraviolet curable resin to form a fiber type coupler (see FIG. 2(e)). ).

Next, experimental results of the fiber coupler according to the above embodiment will be explained based on FIG. This experiment was conducted after the fiber coupler was drawn to a predetermined branching ratio in the drawing process (
(cooled to room temperature), tensile force was applied to coupler part A (outer diameter: approximately 20 μm) by pulling the fiber coupler in the optical axis direction, and the probability of breakage was investigated for 70 fiber couplers. It is. In this case, the length between the fiber gripping members is set to 25 mm, and the moving distance ΔL is set to 50 mm.
μm, 100 μm, and 150 μm, and pulled for 10 seconds.

In FIG. 3, the probability of breakage when a fiber coupler is created is shown by a solid line. According to this experiment, the moving distance Δ
It can be seen that as L increases, the probability of breakage increases rapidly.

Next, the fiber type coupler whose rupture probability was tested was subjected to a heat cycle test 20 times as shown in FIG. 3(b). In this heat cycle test, the manufactured fiber coupler was left at 20°C for 1 hour, heated to 100°C for 1 hour, left at 100°C for 1 hour, and then cooled to -40°C for 1 hour. ℃ in 1 hour to complete one cycle.

In FIG. 3(a), the results of this heat cycle test are indicated by dotted lines. According to this experimental result, the moving distance Δ
It can be seen that fiber couplers with L of 100 μm or more have a particularly low probability of breakage (close to 0%). This is considered to be because the fiber type coupler with low breaking strength was removed by increasing the moving distance ΔL.

The fiber type coupler used in this experiment is a fiber type coupler with a branching ratio of 50%, and branches the transmitted light having a wavelength of 1.3 μm by 50%.

In this case, the excess loss was all 0.1 dB or less, and ceramic (MgOs) was used as the protective member (molded case).

Furthermore, the stage that fixes the fiber gripping member to stretch the fiber coupler in the optical axis direction is controlled by a pulse motor and computer, and stretching, tension application, etc. are controlled with micron precision.

Note that this invention is not limited to the above embodiments. For example, the branching ratio is not limited to 50% (
It can be applied to fiber couplers that propagate light of not only a single wavelength but also multiple wavelengths.

In addition, when applying tension to a fiber coupler using a fiber gripping member, etc., appropriate moving distance, moving speed, atmospheric conditions, etc. are set in consideration of the outer diameter, material, shape, etc. of the coupler. For fishing, it is effective to pull at a moving speed of 10 μm/sec over a moving distance of 5 times or more the outer diameter of the coupler.

〔Effect of the invention〕

Since this invention is configured as explained above,
The reliability of the fiber coupler can be improved.

In particular, in a fiber coupler that splits light by 50% at 1.3 μm, 10
+100℃, -40℃ by applying tension for seconds
Even during heat cycles under such severe conditions, no breakage occurs, significantly improving reliability.

4 are flowcharts showing a method of manufacturing a fiber coupler according to the prior art.

1.2...Optical fiber core wire 3...Heating device 4...Protection member A...Coupler part Patent applicant Sumitomo Electric Industries Co., Ltd. Patent attorney Representative Patent attorney Yoshi Hase Yoshikima Yama 1) Light
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[Brief explanation of the drawing]

FIG. 1 is a flowchart showing a method for manufacturing a fiber coupler according to an embodiment of the present invention, FIG. 2 is a process diagram showing a manufacturing process of this fiber coupler, and FIG. 3 is an experiment according to the present invention. Figure showing the results (b) Figure 3 of experimental results

Claims (1)

[Scope of Claims] A first step of forming a coupler member by stretching at least two or more optical fibers from which the coating has been removed in the direction of the optical axis while fusing them; A second step of applying a predetermined tension to inspect whether or not the coupler member is broken; and a third step of fixing the unbroken coupler member to a protective member to form a fiber coupler. A method of manufacturing a fiber coupler.