JP2875427B2 - Manufacturing method of optical fiber coupler - Google Patents

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 used in a communication system, a sensor system, and the like.

[0002]

2. Description of the Related Art An optical fiber coupler for splitting / coupling or splitting / combining light has a small transmission loss and is almost an indispensable optical component for installing an optical communication system. An optical fiber coupler is usually formed by heating and fusing a bundle of a plurality of optical fibers, and stretching the joined portion.

In the production of optical fiber couplers, it is required that the dispersion of transmission loss is small and the reliability of quality is stable. In order to manufacture optical fiber couplers with small variations in transmission loss with good yield, it is necessary to minimize uneven heating when fusing the optical fiber bundle. For this purpose, it is necessary to stably heat the optical fiber bundle for a predetermined time with a flame in a steady state even when wind is received during manufacturing. JP-A-3-1386
No. 09 discloses a method of enclosing a flame with a windproof cover.

[0004] The cause of flame sway is not only wind. In some cases, the mechanical vibration of the stretching motor, which is the power source for stretching the optical fiber bundle, is directly transmitted to the burner, causing the flame to shake. For this reason, Japanese Patent Laid-Open Publication No. 3-15409 discloses a method of manufacturing an optical fiber coupler in which a stretching mechanism of an optical fiber coupler manufacturing apparatus and a burner installation table are completely separated so that mechanical vibration of a stretching motor is not transmitted to the burner. Machine has been proposed.

[0005]

Optical fiber couplers generally require low optical transmission losses. In any of the above methods, the optical transmission loss cannot be sufficiently reduced. To reduce the optical transmission loss, refer to
As proposed in Japanese Patent Publication No. 211507, the position of the flame of the burner may be constantly moved in the extending direction of the optical fiber bundle, and the fused portion may be formed long. However, when the burner is actually moved, the flame fluctuates with the burner, and as a result, the optical transmission loss of the optical fiber coupler varies. For this reason, there has been a problem that it has been difficult to manufacture an optical fiber coupler with small optical transmission loss and small variation with high yield.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide a method for manufacturing an optical fiber coupler having a small variation in optical transmission loss and a small optical transmission loss with a high yield.

[0007]

A method of manufacturing an optical fiber coupler according to the present invention, which has been made to achieve the above object, will be described with reference to FIG. 1 which is an external view of an apparatus for manufacturing an optical fiber coupler.

The present invention relates to a method for manufacturing an optical fiber coupler, in which a fused portion is stretched while partially heating and fusing an optical fiber bundle 20 with a flame of a movable burner 1 to couple an optical path of an optical fiber. The movable burner 1 is reciprocated in the stretching direction of the optical fiber bundle 20 at a moving speed higher than the stretching speed while heating the portion.

The moving speed of the movable burner 1 is 1.5 to 30 times the drawing speed of the optical fiber bundle 20, preferably 10 to 2 times.
It is good to be 0 times.

[0010]

The movement of the flame of the movable burner 1 which tends to swing in the width direction of the optical fiber bundle 20 is sufficiently absorbed by the swing of the movable burner 1 in the movement direction by the relatively fast movement of the movable burner 1, and the movement of the movable burner 1 is suppressed. Flame is an optical fiber bundle 2
Oscillating in the stretching direction along 0, the whole fused part is heated on average.

[0011]

Embodiments of the present invention will be described below. FIG. 1 is an external view of a fusion device for carrying out the method of manufacturing an optical fiber coupler of the present invention. This fusion device is a device in which an optical fiber bundle 20 is heated by a movable burner 1 and stretched by a first stretching movement stage 2 and a second stretching movement stage 3 to couple an optical path of an optical fiber.

A stage guide groove 5 is formed in the center of the base 4, and a stage motor 6 is provided at an end of the upper surface. A stage feed screw rod 7 is rotatably arranged in the stage guide groove 5. The stage feed screw rod 7 has a left-hand screw on one side and a right-hand screw on the other side with the center in the longitudinal direction as the center. The tip of the rotation center axis of the stage feed screw rod 7 is linked to the stage motor 6 by a gear. The first and second extension movement stages 2 and 3 are provided on a base 4, and the foot portions 8 protrude from the lower surfaces thereof and are fitted into the stage guide grooves 5. The foot 8 is provided with a female screw hole, and the first extension moving stage 2 is screwed to the left screw of the stage feed screw rod 7 by the foot 8, and the second extension moving stage 3 is screwed to the right screw. doing. A fastening plate 9 is screwed to each of the upper ends of the first and second extension movement stages 2 and 3.

A burner installation board 9 on which the movable burner 1 is installed is provided between the first and second extension movement stages 2 and 3. A reversible motor 10 is installed on the upper surface of the burner installation board 9, and a burner guide groove 11 is provided immediately above and parallel to the stage guide groove 5. A burner feed screw rod (not shown) is rotatably arranged in the burner guide groove 11, and the burner feed screw rod is interlocked with the reversible motor 10 via a gear. The movable burner 1 for discharging the oxyhydrogen gas flame is provided on the upper surface of the burner installation board 9. The movable burner 1 has a burner foot 12 having a female screw hole. The burner foot 12 is fitted into the burner guide groove 11, and the movable burner 1 is screwed with the burner feed screw rod through the female screw hole.

A laser light source 21 for inputting laser light to the optical fiber and a light quantity measuring device 22 for measuring the amount of light emitted from the optical fiber are provided near the base 4.

Using this fusion device, an optical fiber coupler was manufactured as follows. Two optical fibers each having a thickness of 125 μm were bundled and fixed with the clamping plates 9 of the first and second stretching moving stages 2 and 3 which were 2.5 cm apart. An end of one optical fiber of the optical fiber bundle 20 is connected to a laser light source 21,
The other end of the optical fiber was connected to the light amount measuring device 22, and the target splitting ratio of light at the fusion portion was set to 50%. The movable burner 1 was ignited, and the reversible motor 10 was continuously rotated forward and backward alternately to make the movable burner 1 reciprocate along the burner guide groove 11. The moving speed was 2.5 mm / sec.

The amount of the light from the laser light source 21 appearing at the end of the other optical fiber is observed by the light amount measuring device 22, and the first and second light amounts are measured.
The stage motor 6 is rotated from the time when the optical fiber bundle 20 begins to partially fuse between the first and second stretching movement stages 2 and 3, and the first and second stretching movement stages 2 and 3 are separated from each other. The optical fiber bundle 20 was stretched by running in the direction.
The stretching speed was 0.17 mm / sec.

As in the case of the optical fiber bundle 20, a total of two bundles are used.
Zero optical fiber bundles were prepared, and a total of 20 optical fiber couplers were manufactured for each optical fiber bundle in the same manner as described above. The standard deviation of optical transmission loss was calculated. The standard deviation was 0.07dB.

Comparative Example 1 As in the case of the optical fiber bundle 20 of the embodiment, a total of 20 optical fiber bundles were prepared in two bundles. A total of 20 optical fiber couplers were manufactured one by one in the same manner as in Example 1 except that the traveling speed of the movable burner 1 was set to 0.17 mm / sec, which was the same as the stretching speed of the optical fiber bundle. The standard deviation of the optical transmission loss was 0.15 dB.

Comparative Example 2 As in the case of the optical fiber bundle 20 of the embodiment, a total of 20 optical fiber bundles were prepared in two bundles. Except that the traveling speed of the movable burner 1 was set to 0.10 mm / sec, which was lower than the drawing speed of the optical fiber bundle, a total of 20 optical fiber couplers, one for each optical fiber bundle, were connected in the same manner as in Example 1. Manufactured. When the standard deviation of the optical transmission loss was determined.
It was 13dB.

It has been found that when the moving speed of the movable burner 1 is higher than the stretching speed, the variation in optical transmission loss is small and the production yield can be improved.

[0021]

As described in detail above, according to the method for manufacturing an optical fiber coupler of the present invention, the flame oscillates along the optical fiber bundle in the direction in which it extends, and the variation in optical transmission loss is small. An optical fiber coupler with small optical transmission loss can be manufactured with high yield.

[Brief description of the drawings]

FIG. 1 is an external view of a fusion device for carrying out a method of manufacturing an optical fiber coupler according to the present invention.

[Explanation of symbols]

1 is a movable burner, 2 is a first extension movement stage, 3 is a second extension movement stage, and 20 is an optical fiber bundle.

Claims (2)

(57) [Claims] In a method of manufacturing an optical fiber coupler, a fusion spliced portion is stretched while partially fusing an optical fiber bundle with a flame of a movable burner, and the optical path of the optical fiber is coupled. A method for manufacturing an optical fiber coupler, wherein a movable burner is reciprocated in a stretching direction of an optical fiber bundle while moving at a speed higher than a stretching speed. 2. The method according to claim 1, wherein the moving speed of the movable burner is 1.5 to 30 times the drawing speed of the optical fiber bundle.