JPH02140708A - Production of fiber type coupler - Google Patents

Abstract

PURPOSE:To improve reproducibility and the yield at the time of production by removing the coatings of the multiple optical fibers integrated under the same tension, fixing the plural optical fibers from which the coatings are removed into the state of bringing the fibers into contact with each other and welding and stretching the fibers. CONSTITUTION:The optical fibers 1, 1 are juxtaposed in a longitudinal direction and the coatings 2 are applied thereon, by which the fibers are integrated under the same tension. The coatings 2 and the primary coatings of the optical fibers 1, 1 are partly removed and the plural optical fibers 1, 1 which are bare fibers are positioned from the directions by horizontal and vertical position adjusting members 3 to 10, by which the optical fibers are brought into contact with each other and are fixed. The plural optical fibers 1, 1 which are in contact with each other are welded and stretched by an acetylene burner 11. The branching ratios of the welding and stretching are monitored at this time and the stretching is stopped at the time when the branching ratio attains a prescribed value, by which the fiber type coupler is produced. The bending and twisting in the welding and stretching stage are easily decreased in this way and the reproducibility and the yield at the time of production are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a fiber coupler formed by fusing and drawing a plurality of optical fibers.

[Conventional technology]

Fiber couplers split and split light between multiple optical fibers.
Currently, the melt-drawing method is considered to be the most suitable method for manufacturing single-mode fiber couplers ("Recent optical fiber coupler technology", Obtronics (1988) No. 5, p. 125). ) This fusion-stretching method involves twisting or fusing multiple optical fibers in parallel to bundle them, and then stretching the bundled portions while heating and fusing them with a heater such as a burner. Given characteristics (
The stretching is stopped when the desired amount (branching ratio, etc.) is obtained.

In this case, the optical fiber uses a vertical adjustment device to adjust the vertical position and a horizontal position adjustment device to adjust the horizontal position,
A plurality of optical fibers are inserted and positioned from the vertical and horizontal directions.

However, according to the positioning method from two directions as described above, when the optical fiber is fixed to the optical fiber fixing member, a difference occurs in the tension applied to each optical fiber.

FIG. 5 is a perspective view showing the influence of tension in the fusion process. Figure (a) shows a fiber coupler manufactured when the tension applied in the fusion process is constant, and Figure (b) shows a fiber coupler manufactured when the tension applied in the fusion process is different. This figure shows a fiber-type coupler that can be used. If the applied tensions are different, the tension is released in the molten state, causing bending and twisting at the fused portion A.

Such bending and twisting at the fused portion A increases the insertion loss of the fiber coupler, and since the bending state is not constant, the reproducibility of the fiber coupler decreases, resulting in poor yield.

In order to eliminate such drawbacks, the manufacturing equipment has been modified (Japanese Patent Application Laid-Open No. 118705/1983). According to this device, in the position adjustment process during the manufacturing process of a fiber coupler, the tension applied to each optical fiber is equalized by fixing the optical fiber to a moving stage to which a certain force is applied. The position of the optical fiber was adjusted to reduce bending and twisting of the fused part.

[Problem to be solved by the invention]

However, in order to keep the tension constant, conventional manufacturing equipment requires equipment to balance the tension. Furthermore, as the diameter of the optical fiber decreases or as the number of fibers increases, it becomes difficult to equalize the tension, and highly accurate control becomes necessary. Therefore, there was a drawback that the device was expensive.

Therefore, the present invention aims to improve the yield during manufacturing by providing a manufacturing method that can easily reduce bending and twisting during the fusing and stretching processes and has good reproducibility. .

[Means to solve the problem]

In order to achieve the above object, the present invention provides a method for manufacturing a fiber coupler formed by fusing and drawing a plurality of optical fibers. a first step of removing the coating, a second step of fixing the plurality of optical fibers from which the coating has been removed in contact with each other, and fusing and fusing the plurality of optical fibers in contact.
and a third step of stretching.

[Effect]

Since the present invention is configured as described above, the tension existing in the plurality of optical fibers constituting the fiber coupler is constant at the stage of being fused.

Therefore, bending and twisting during the fusing/stretching process can be eliminated.

Since this tension can be set to a predetermined value at the stage of forming the multicore optical fiber, the reproducibility of the fiber coupler can be improved.

〔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 flowchart showing a method of manufacturing a fiber coupler according to this embodiment, and FIG. 2 is a process diagram of the fiber coupler according to this embodiment.

In step 101, a plurality of optical fibers 1.1 each having a second coating are placed side by side in the longitudinal direction (optical axis direction).
(See figure (a)), and by applying the cover 2, they are integrated with the same tension (see figure (b)). In this case, the optical fibers to be integrated are optical fibers without a secondary coating,
Alternatively, it may be an optical fiber coated with a secondary coating.

What is important is that the optical fiber is kept under constant tension. Therefore, for example, a multi-core optical fiber core (see Japanese Patent Laid-Open No. 61-63810) may be used in which two coated optical fibers are supplied with equal tension and are integrated. Note that the optical fiber wire 1 to be integrated,
1 may not be arranged in parallel.

In step 102, the coating 2 of the integrated multi-core optical fiber and the primary coating of the optical fibers 1 and 1 are partially removed (see figure (c)), and a plurality of bare optical fibers are removed. By positioning 1.1 in two directions, they are brought into contact with each other and fixed (step 103). in particular,
Adjust the horizontal position with the horizontal position adjustment member 3.4.5.6 as described above, and use the vertical position adjustment member 7.8.9.1.
0 to adjust the vertical position (see Figure 2(d)).

In step 104, the contacting plurality of optical fibers 1%1
are fused and stretched using an acetylene burner 11 (see Figure 2(e)).
)reference). For example, as shown in FIG.
．． A light source 12.13 such as an LED is connected to one end of 1, a power meter (PM) 14.15 is connected to the other end, and three burners 16, 17, 18 are arranged in the optical axis direction as a heater. It can be carried out. In this case, the branching ratio during fusing and stretching is monitored (step 105).

When the branching ratio reaches a predetermined value, the stretching is stopped (step 106), and when the branching ratio does not reach the predetermined value, the fusion and stretching are continued (step 104). At step 106, a fiber coupler is manufactured (see FIG. 2(f)).

Note that this invention is not limited to the above embodiments. For example, the number of optical fibers is not limited to two, and single mode fibers, multimode fibers, etc. can be used.

Further, as the optical fiber, a dispersion-shifted fiber in which the zero dispersion wavelength is shifted to the 1.55 μm band in which silica-based optical fiber exhibits the lowest loss can be used.

Next, experimental results related to this invention will be explained. In this experiment, a two-core tape-shaped optical fiber core wire was made by integrating two optical fibers in parallel, and the loss when the optical fibers were fused together was measured. First, the manufacturing conditions of the fiber coupler used in the experiment will be explained.

The optical fiber used in the fiber coupler according to the present invention is a single-mode fiber with an MFD of 9.5±1 μm and a normal wavelength of 1.3 μm, and is finished with an ultraviolet curing resin to have an outer diameter of 250 μm.

These optical fiber wires were arranged at a predetermined pitch and finished with an ultraviolet curing resin to a width of 0.6 mm and a thickness of 0.4 mm. In this case, the tape tension is 50 ± 2 g, and the linear speed is 40
A 300 m trial tape was produced at m/min. The fusion conditions when forming a fiber type coupler are a clamp interval of 8
mm, and an LED with a wavelength of 1.3 μm was used as a light source. In addition, the heater is acetylene oxygen (acetylene 121 cm
3/min, oxygen 30cm3/min) as combustion gas, hole diameter 0
．． Three 2mm burners were arranged in the optical axis direction (
(See Figure 3). In this case, the three burners are 5mm and 3m.
m, the interval was 5 mm, and the fusion time was 30 seconds.

In the conventional method, two optical fibers were fixed one by one, and the tension was carefully balanced to be even.

FIG. 4 shows the results of the above experiment. In this figure, the power change (attenuation bone) is calculated from the light source and power meter connected to each fiber as a loss in fusion splicing, and this is graphed as a frequency distribution. Same figure (
a) is produced by the manufacturing method according to the present invention;
b) is based on a conventional manufacturing method. This experiment shows that the fiber coupler manufacturing method of the present invention causes less loss during fusion and has higher reproducibility than conventional manufacturing methods.

〔Effect of the invention〕

Since this invention is configured as explained above,
Bending and twisting in the fusing/stretching process can be easily reduced, and a manufacturing method with good reproducibility can be provided. Therefore, the yield during manufacturing can be improved.

In addition, the tension of the optical fibers used in the coupler is equalized, the coating of the integrated multi-core optical fiber core wire is removed, and the fibers are fused and stretched to produce a fiber-type coupler. Compared to the conventional manufacturing method of attaching and fixing with clamps, loss during fusion is greatly reduced.

Furthermore, since a plurality of optical fibers are integrated, the number of times the fibers are handled is reduced and the working time can be shortened.

By the way, there is a tape-shaped optical fiber core as a multi-core optical fiber, and it is possible to integrate the tape-shaped optical fiber core by coaching and fusing the optical fiber with a non-adhesive material. A method for separating optical fiber strands into pieces has been developed. Using this tape-shaped optical fiber core makes it extremely easy to branch out individual optical fibers.・12. 14, 3...Light source 5...Power meter

[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 method for manufacturing a fiber coupler according to an embodiment of the invention, and FIG. is an explanatory diagram showing a monitoring method that can be applied to the method of manufacturing a fiber coupler according to the present invention, FIG. 4 is a graph showing experimental results according to the present invention, and FIG. 5 is a graph showing the tension in the fusion process It is an explanatory diagram showing the influence of. 1... Optical fiber strand 2... Covering 3.4.5.6... Horizontal position adjustment member 7.8.9.1
0... Vertical position adjustment member 11... Acetylene burner patent applicant Sumitomo Electric Industries Co., Ltd. Patent attorney Yoshi Hasekima
Mountain 1) Loss during fusion splicing Manufacturing method of fiber type coupler Experimental results Loss during fusion 1 Fig. 1

Claims (1)

[Claims] A method for manufacturing a fiber coupler formed by fusing and drawing a plurality of optical fibers, the first step being to remove the covering of the integrated multi-core optical fiber under the same tension. a second step of fixing a plurality of optical fibers from which the coating has been removed in contact with each other; and a third step of fusing and stretching the plurality of optical fibers in contact with each other. A method of manufacturing a fiber type coupler comprising: