JPH07333457A - Production of optical fiber coupler - Google Patents

Abstract

PURPOSE:To provide a process for housing the characteristics of all optical fiber couplers in a desired range in a process for simultaneously producing plural pieces of the optical fiber couplers. CONSTITUTION:The coatings of two pieces of optical fiber ribbons 5, 6 are removed over a prescribed length in central parts and the bare fiber parts are brought into tight contact with each other in the state of exposing these parts and are fixed to fiber clamps 7. The light from a light source 1 is branched by the optical fiber couplers 2, 3, 4 for branching and the branched light rays re-made incident on the optical fiber ribbon 5. The exit ends of the optical fiber ribbons 5, 6 are respectively connected to optical power meters 8. The respective bare fiber parts are heated and fused by a gas burner 9 and while the fused parts are further heated, the spacing between the fiber clamps 7 is widened, by which the fused parts are stretched. The branching ratios are calculated by a microcomputer 10 from the outputs of the optical power meters 8. The stretching is stopped at the point of the time the branching ratios of all the optical fiber couplers attain the prescribed values.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical fiber coupler.

[0002]

2. Description of the Related Art A plurality of sets of optical fibers are fused and stretched,
A method of collectively manufacturing a plurality of optical fiber couplers is known. Tape-shaped optical fibers are suitable for this method. For example, using two 4-core tape-shaped optical fibers,
Each tape-shaped optical fiber, in a state in which the bare fiber portion is exposed by removing the coating over a predetermined section at the lengthwise position, and the opposing bare fiber portions are adhered to each other,
After heat fusing, the fused portion can be heated and stretched to form four optical fiber couplers.

When a plurality of optical fiber couplers are manufactured collectively by this method, it is necessary to keep the characteristics of the plurality of optical fiber couplers within a desired range. For this purpose, it is important to reduce variations in characteristics among the optical fiber couplers and to stop the stretching at any timing.

As an example, FIGS. 2 and 3 show the relationship between the amount of extension and the branching ratio when four optical fiber couplers are manufactured in a lump by using two four-fiber optical fibers. Figure 3
[Fig. 3] is an enlarged view of a portion surrounded by a dotted circle in Fig. 2. There is a slight variation in the characteristics between the optical fiber couplers, and the greater the amount of extension, the greater the variation in the characteristics.

It is considered that this variation is due to uneven tension applied to each optical fiber, uneven heating condition due to the burner or fluctuation, and uneven pressing due to the fiber clamp. For example, in the case of using a four-fiber tape-shaped optical fiber, when the coupler section is formed in a state where the interval between the bare fiber sections in the fusion splicing area is wider than the interval between the core wires in the tape-shaped optical fiber, The line pattern is as shown in Fig. 4, and if you call it the 1st, 2nd, 3rd, 4th from the top of the figure, the 1st and 4th paths are longer than the 2nd and 3rd paths. The 1st and 4th will be given more tension than the 2nd and 3rd. Therefore, in the drawing process,
The second tends to have a larger stretch amount and a higher branching ratio than the second and third. 2 and 3 show the tendency.

Therefore, as in the conventional method,
If only the characteristics of one optical fiber coupler are monitored and the extension is stopped based on this monitoring result, the characteristics of the other optical fiber coupler may not fall within the desired range. For example, in FIG. 3, the desired branching ratio is 50 ±
In the case of 5%, if the first optical fiber coupler is monitored and the extension is stopped when the branching ratio becomes 45%, the second and third optical fiber couplers have a branching ratio of 4%.
There is a problem that the stretching is stopped in a state where it has not reached 5%.

[0007]

In order to solve this problem, in the present invention, the characteristics of two or more or all optical fiber couplers are monitored, and the extension is stopped based on the monitoring result. It is an object of the present invention to provide a method for manufacturing an optical fiber coupler which can bring the characteristics of all the optical fiber couplers into a desired range.

[0008]

According to a first aspect of the present invention, in the method of manufacturing an optical fiber coupler, a plurality of sets of optical fibers are fused and extended to collectively form a plurality of optical fiber couplers. It is characterized in that at the time of manufacturing, the stretching is performed while monitoring the characteristics of two or more optical fiber couplers, and the timing of the stretching stop is determined based on the monitoring result.

According to a second aspect of the present invention, in the optical fiber coupler manufacturing method according to the first aspect, the extension is performed when the insertion loss of all the optical fiber couplers being monitored reaches a desired value. The invention according to claim 3 is characterized in that
In the method for manufacturing an optical fiber coupler as described in (3) above, the stretching is stopped when the branching ratios of all the optical fiber couplers being monitored reach a desired value.

According to a fourth aspect of the invention, in the method of manufacturing an optical fiber coupler according to the first aspect, stretching is performed while monitoring the characteristics of all the optical fiber couplers, and the stretching is performed based on the result of the monitoring. The feature is that the timing of stop is determined.

According to a fifth aspect of the invention, in the method of manufacturing the optical fiber couplers according to the fourth aspect, the stretching is stopped when the insertion loss of all the optical fiber couplers reaches a desired value. According to the invention described in claim 6, in the method for manufacturing an optical fiber coupler according to claim 4, the stretching is performed when the branching ratios of all the optical fiber couplers reach a desired value. It is characterized by stopping.

According to a seventh aspect of the present invention, in the method for manufacturing an optical fiber coupler according to any one of the first to sixth aspects, the same light for monitoring the characteristics of a plurality of optical fiber couplers is used. It is characterized by branching from a light source.

[0013]

According to the present invention, by monitoring the characteristics of all the optical fiber couplers and determining whether or not to stop the drawing, the characteristics of the optical fiber couplers manufactured in a batch can be kept within a desired range. As described above, it is desirable to monitor the characteristics of all the optical fiber couplers, but if there are restrictions on the measuring instrument for monitoring, it is also possible to monitor the characteristics of a plurality of optical fiber couplers that are not the total number. For example,
As described with reference to FIGS. 2 to 4, when the branching ratio of the outer optical fiber coupler tends to be larger than the branching ratio of the inner optical fiber coupler, one outer optical fiber coupler and one inner optical fiber coupler are used. By monitoring the characteristics of one optical fiber coupler, the characteristics of all the optical fiber couplers can be kept within a desired range.

By branching the light for monitoring the characteristics of a plurality of optical fiber couplers from the same light source, even if there is a change in the light amount of the light source, all monitors will be affected in the same way. The effects of fluctuations can be avoided.

The insertion loss or the branching ratio can be considered as a parameter for determining the stop of the stretching.
The required characteristics may be used as parameters.
When both insertion loss and branching ratio characteristics are required, it is better to use the more strict characteristics as the parameter for stopping stretching.

The stretching can be stopped by an appropriate method such as stopping the application of tension, stopping heating, or stopping both.

[0017]

1 is a conceptual diagram of a manufacturing apparatus to which an embodiment of a method for manufacturing an optical fiber coupler according to the present invention is applied. In the figure, 1 is a light source, 2 to 4 are optical fiber couplers for branching, 5 is a tape-shaped optical fiber for main line, 6 is a tape-shaped optical fiber for branch line, 7 is a fiber clamp, 8 is a power meter, 9 is a gas burner, 10 is a microcomputer.

The light having a wavelength of 1.3 μm emitted from the light source 1 is split into two by the branching optical fiber coupler 2 with an optical power of 1: 1, and further the branching optical fiber couplers 3 and 4 have an optical power of 1: 1. It is branched into 4 in 1: 1: 1. Each of the four branched lights is incident on the four-line main-line tape-shaped optical fiber 5. The tape-shaped optical fiber 5 for main line and the tape-shaped optical fiber 6 for branch line are both formed by aligning single-mode fibers for a wavelength of 1.3 μm into a tape shape.
The coating is removed from the central portion over a predetermined length, and the bare fiber portion is exposed, and the main line tape-shaped optical fiber and the branch line tape-shaped optical fiber are adhered to each other.
It is fixed to the fiber clamp 7. The emission ends of the main-line tape-shaped optical fiber 5 and the branch-line tape-shaped optical fiber 6 are respectively connected to the optical power meter 8 so that the characteristics of each optical fiber coupler can be monitored.

In this state, the bare fiber portion of each tape-shaped optical fiber was heated by the gas burner 9 and fused, and the fiber clamp was stretched by further heating the fused portion while increasing the distance between the fiber clamps. As the stretching progresses,
Since the coupling of light from the tape-shaped optical fiber 5 for main line to the tape-shaped optical fiber 6 for branch line progresses, the optical power from the tape-shaped optical fiber 5 for main line decreases, and the optical power from the tape-shaped optical fiber 6 for branch line decreases. Will increase. This situation is measured by the optical power meter 8, and the insertion loss or the branching ratio is calculated by the microcomputer 10. In this embodiment, the target branching ratio is 50 ± 5%, and the branching ratio is 4 for all four optical fiber couplers.
Since the stretching was stopped at the time when it exceeded 5%, a computer program was created to extinguish the gas burner 9 and stop the movement of the fiber clamp 7. As a result, the branching ratio of each optical fiber coupler changes as shown in FIGS. 1 and 2, for example, as the amount of extension, that is, the spacing between the fiber clamps 7 increases, and the branching ratio of the third optical fiber coupler changes. Stretching was stopped at a time point of 45%.
At this time, the first branching ratio of each optical fiber coupler is 5
It was confirmed that 2%, the second 48%, and the fourth 53% all met the target of 50 ± 5%.

[0020]

As is apparent from the above description, according to the present invention, in the manufacturing method for manufacturing a plurality of optical fiber couplers at the same time, the characteristics of each optical fiber coupler can be kept within a desired range. There is.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a manufacturing apparatus to which an embodiment of a method for manufacturing an optical fiber coupler according to the present invention is applied.

FIG. 2 is a diagram showing a relationship between a stretching amount and a branching ratio.

FIG. 3 is an enlarged view of a portion surrounded by a dotted circle in FIG.

FIG. 4 is an explanatory diagram of a core wire pattern when a four-core tape-shaped optical fiber is used.

[Explanation of symbols]

1 ... Light source, 2-4 ... Optical fiber coupler for branching, 5 ... Tape optical fiber for main line, 6 ... Tape optical fiber for branch line, 7 ... Fiber clamp, 8 ... Power meter, 9 ... Gas burner, 10 ... Micro Computer.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoichi Ishiguro 1 Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industries, Ltd. Yokohama Works (72) Inventor Shigeru Semura 1-tani, Saya-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industry Co., Ltd. Yokohama Works

Claims (7)

[Claims] 1. When a plurality of sets of optical fibers are fused and drawn to collectively manufacture a plurality of optical fiber couplers, the drawing is performed while monitoring the characteristics of two or more optical fiber couplers, and the monitoring results are shown. A method for manufacturing an optical fiber coupler, characterized in that the timing of stopping the drawing is determined based on the drawing. 2. The method of manufacturing an optical fiber coupler according to claim 1, wherein the extension is stopped when the insertion loss of all the optical fiber couplers being monitored reaches a desired value. 3. The method of manufacturing an optical fiber coupler according to claim 1, wherein the stretching is stopped when the branching ratios of all the optical fiber couplers being monitored reach a desired value. 4. The manufacturing of the optical fiber coupler according to claim 1, wherein the optical fiber coupler is stretched while monitoring the characteristics of all the optical fiber couplers, and the timing for stopping the stretching is determined based on the result of the monitoring. Method. 5. The method of manufacturing an optical fiber coupler according to claim 4, wherein the stretching is stopped when the insertion loss of all the optical fiber couplers reaches a desired value. 6. The method of manufacturing an optical fiber coupler according to claim 4, wherein the stretching is stopped when the branching ratios of all the optical fiber couplers reach a desired value. 7. The method of manufacturing an optical fiber coupler according to claim 1, wherein the light for monitoring the characteristics of the plurality of optical fiber couplers is branched from the same light source.