JPH0766090B2 - Reinforcing method of fusion spliced part of multi-core optical fiber - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fusion spliced portion of a multi-core optical fiber by applying tension for improving reliability of splicing strength of a multi-fiber optical fiber having a fusion spliced portion. Reinforcement method.

<Prior Art> (A) Technical Background In order to put an optical fiber communication system into practical use, it is necessary to establish a multi-fiber optical fiber connection technology for constructing an optical cable line. Various methods such as a fusion splicing method and a V-groove connection method have been proposed as a method of connecting a multi-core optical fiber. The fusion splicing method is the best in terms of workability and low loss in the field. However, communication lines must maintain stable characteristics for a long period of time, and long-term reliability of cables and connections must be ensured.

The splicing strength of the multi-fiber optical fiber fusion splicing part is 0.1 to 1 per bare fiber due to the effects of coating removal and thermal strain during splicing.
It is kg, which is about 1/10 of that in the case of a cable, and it is strongly desired to improve the reliability of the connection part.

There are two conceivable methods for improving the reliability of the connection part, namely, development of an optimum reinforcing method and enhancement of the strength of the connection part itself. However, it is difficult to improve the reliability only by the reinforcement method even if the connection strength is extremely low. In addition, regarding the enhancement of the strength of the fusion spliced part, a method of chemically removing the primary coating of the optical fiber core and connecting without damaging the surface of the bare fiber, or after the splicing, the fusion spliced part is treated with hydrofluoric acid Although methods have been proposed, all of them use dangerous chemicals, so they are difficult to apply to work in a manhole or in an aerial environment.

On the other hand, when considering the long-term reliability of the optical fiber splicing part, only a part of the splicing part having extremely low strength becomes a problem.
The cause of these low-strength connections was attributed to scratches.

Therefore, the long-term reliability of the connecting portion of the optical fiber core is improved by first removing the fiber having the weak connecting portion before the reinforcing treatment, that is, by so-called "screening", to obtain a connecting strength of a certain value or more. It is considered that this can be achieved by reinforcing only the optical fiber.

(B) Prior art closest to the present invention Conventionally, the following devices have been used for screening and reinforcement of a single-fiber optical fiber connection part.

B) The coating 003 on the tip of the single-core optical fiber 001.001 is removed as shown in FIGS.
2,002 exposed, and the tip of these bare fibers 002,002
After abutting as shown in FIGS. (A) and (b) and fusion-splicing at the connection point 004a (hereinafter, this fusion-splicing point is referred to as “fusion-splicing point”), as shown in FIG. 6 (a), A single part of the single-core optical fiber cores 001, 001 is supported by the clamp part 101 of the tension applying device 100 so that the fusion splicing point 004 is in the center, and a load is applied in the direction of the arrow so that a constant tension T is applied. Except for the broken optical fiber core, the unbroken optical fibers are removed from the clamp 101 and then transferred to the reinforcing device 200 shown in FIG. 6 (b), where the bare fibers 002 and 002 are placed around the fusion splicing point 004. 10 Heat shrink tube 00 as shown in Figures (a) and (b)
5 Or cover the reinforcing member 006 and the heat fusion agent 006a, 006b, and in the reinforcing device 200, heat with the heater 201,
The tube 005 was contracted and brought into close contact, and the fusion splicing point 004 of the bare fiber 002,002 was reinforced.

Further, as described above, in the reinforcing method shown in FIGS. 6 (a) and 6 (b), after the optical fibers are screened by the separate devices 100 (tension loading device) and 200 (reinforcing device), the periphery of the fusion splicing point is examined. There is a possibility that new fine scratches will be generated to reinforce the possibility that new fine scratches will be generated, but such new fine scratches will be reinforced without any chance of being found. Therefore, there is a drawback that the long-term reliability of the connection strength of the optical fiber core is not improved.

B) In order to improve the above-mentioned drawbacks of the conventional apparatus, the method disclosed in
In Japanese Patent Application No. 58-220114 (Japanese Patent Application No. 57-104376), an optical fiber reinforcing device 300 with a tension applying device having a structure in which the above-mentioned tension applying device 100 and a reinforcing device 200 are connected as shown in FIG.
Was proposed.

The optical fiber reinforcing device 300 with a tension load device holds the optical fiber core wire 1 having the fusion splicing point 5 from both sides,
In order to apply a constant tension, the clamp arm 102 of the clamp part 101 is set in the lower table 103 with a spring for screening.
105, 105 are configured so that a constant tension T can be applied to the fusion splicing point 004 in the arrow direction. Further, a heater 201 is provided on the lower table 103, and has a structure in which a heat shrinkable tube 005 covered with a fusion splicing point 004 of the optical fiber core wire 001 held by the clamp portions 101, 101 is arranged so as to be heated. ing.

<Problems to be Solved by the Invention> However, in the above-described conventional optical fiber reinforcing device with a tension applying device, i) the tension applied to the optical fiber core wire can only apply a constant load determined by the spring 105.

ii) The applied tension varies.

iii) In the multi-core optical fiber, since the number and shape of the fibers are different, the applied load and the applying method must be changed, but the adjustment cannot be performed. For example, the screening load for a single-core fiber is usually 180 g, but the tension is zero during reinforcement. On the other hand, the screening tension of a multi-core fiber is 200 to 300 g, but when reinforcing it, if the tension of a single core is set to zero, each bare fiber 002,
Since there is a slight difference in the length between 002, 002, 002, "deflection" occurs and bare wires may contact or intersect with each other, causing wire breakage. I have to keep it. On the other hand, if a load of 200 to 300 g is applied to the fusion splicing point 5 while heating and reinforcing, 200 to 3
There is a problem that the transmission strain increases because the tensile strain of 00g remains in the connection reinforcement part.

Due to such a problem, it is desirable to apply a load of 50 g (but about 10 g per core) to reinforce the fusion splicing point so that tension strain does not remain.

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional tension-loaded optical fiber reinforcing device, and has a function of adjusting the screening load G ₁ and the reinforcing load G ₂ to arbitrary values. The device is used to reinforce the multi-fiber optical fiber.

<Means for Solving the Problems> A method of the present invention for achieving the above-mentioned object is to grip an end portion of an optical fiber core wire around a fusion splicing part of a multi-core optical fiber, and to grip at least one of them. On the side of the section, a tension load device that adjusts the load load on the optical fiber core wire to adjust the load is provided, and a reinforcing device that reinforces the optical fiber fusion splicing part is provided, and tension is applied by the tension load device. After completion of the screening, a tension weaker than the tension at the time of the screening is applied without making the tension zero, and the fusion splicing portion is subsequently reinforced by the reinforcing device.

<Operation> According to the method of the present invention, after the multi-fiber optical fiber is screened, when the fusion spliced portion of the optical fiber is further reinforced, the tension applied to the gripping portion from the state as it is without removing the optical fiber, The tension applying device can be adjusted to be smaller than the load at the time of screening to reinforce the fusion splicing portion, and it is possible to reinforce without leaving any distortion in the fusion splicing portion of the optical fiber.

Further, the optical fiber can be reinforced as an optical fiber having no contact with each other and no intersection, and can be configured as an optical fiber reinforced portion with stable transmission loss.

<Examples> Next, an example of a method for reinforcing a multi-fiber optical fiber by applying tension according to the present invention will be described.

1 to 4 are configuration diagrams of an optical fiber reinforcing device with a tension load device used in an embodiment, in which FIG. 1 is an overall configuration diagram, and FIG. 3 is a schematic configuration diagram of the reinforcing device, FIG. 3 is a heating temperature distribution diagram of the reinforcing device,
FIG. 1 is a perspective view of a tension arm device clamp arm fine movement device in the device of FIG. In the figure, 001 is a multi-core optical fiber, 002 is a bare fiber, 003 is a coating, 004 is a fusion splicing point, 0
05 is a heat shrink tube, 100a is a tension load device, 101 is a clamp part, 102 is a clamp arm, 0 is a clamp arm 102
Support point, 110 is a clamp armau fine movement device, 110a is a moving body, 110b is a zero-point detection sener, 111 is a pulse motor, 1
12 is a speed change gear, 113 is a rotary indexing plate, 114 is a sensor, 115 is a feed screw shaft for moving the moving body 110a back and forth, and 116 is the moving body 110.
Guide rod of a, 117 is a 0 point detection rod, 118 is a low load spring, 1
19 is a screening spring, 120 is an adjusting screw, 121 is a pulse motor control device, 200a is a reinforcing device of an optical fiber reinforcing device with a tension load device of the present invention described later, 200a is a heating heater part, 201a is a heating heater 1, 201b is The heaters 2 and 202 are changeover switches, and 300a is a reinforcing device with a tension load device for carrying out the method of the present invention.

As shown in FIG. 1, an optical fiber reinforcing device 300a with a tension load device of this embodiment has clamp parts 101, 101 for gripping multi-core optical fibers 001, 001 connected at fusion splicing point 004.
And, at least one direction of the clamp parts 101, 101 is moved via the clamp arm 102 so as to apply tension in the direction of the arrow, and the vicinity of the fusion splicing point between the clamp arm fine movement device 110 and the fiber is heated to reinforce the heat shrink tube 005. The heating heater unit 200a is composed of a heating heater unit 200a. As shown in FIG.
The a (high temperature heating) and the heater 201b (low heating) have a structure in which two circuits of the temperature distribution b are overlapped so that the multi-core type temperature distribution a shown in FIG. 3 and the single core type can be used. It is manufactured by sintering a ceramic plate, which is a reinforcing plate, into a flat plate shape.

When the heaters 201a and 201b are wired in the circuit configuration shown in FIG. 2 to reinforce the fusion splicing point of the multi-core optical fiber, the fusion splicing portion is connected to the ceramic plate 006 described above.
Thus, the multi-core heating condition can be obtained by setting the sandwich switch from above and below and operating the changeover switch 202 to the side showing the multi-core type temperature distribution.
That is, after the screening is completed, the tension is not made zero and reinforcement is performed with a tension weaker than the tension at the time of screening.

When reinforcing the single-fiber optical fiber, cover the heat-shrinkable tube 005 around the fusion splicing part and then switch the switch 202.
When is operated to the single core side, the single core heating condition is obtained.

As shown in FIG. 4, the tension load device 100a rotates the pulse motor 111 in response to a signal sent from the pulse motor control device 121.
The feed screw shaft 115 rotates via the 2,112
The moving body 110a mounted on the vehicle moves back and forth along guide shafts 116, 116 provided above and below the moving body 110a. As a result, when moving backward, for example, an extension force acts on the screening spring 119 and a repulsive force is generated in the spring 119. Therefore, the clamp arm 102 is pulled toward the adjustment screw 120 side, and the clamp arm moves backward from the 0 point as a fulcrum. Lean to.

Therefore, the clamp portion 101 above the clamp arm 102 exerts tension on the optical fiber belief 1.

A zero-point detection rod 117 is provided on the side of the clamp arm 102 of the clamp arm fine movement device 110, and a contact point with the zero-point sensor piece 110b on the top of the moving body 110a constitutes a reference position of the clamp arm 102. . The clamp portion 101 is designed so that the tension applied to the optical fiber becomes zero at the reference position.

Further, the rotation speed of the pulse motor 111 and the moving body 110a are set to be directly proportional to each other, and the pulse motor 111 is rotationally driven by the pulse signal sent from the pulse motor control device 121. Further, the feed screw shaft 115 rotates via the transmission gears 112, 112 that rotate together with the rotation of the motor shaft (not shown) of the pulse motor 111, and the rotation index plate 113 attached to the feed screw shaft 115 has even intervals. Bits (8 pieces) are provided, and the bit is detected by the sensor 114 provided on the side of the rotary indexing plate 113. The load applied to the clamp portion 101 via the clamp arm 102 can be read. Clamp arm fine movement device 110
Has a spring force of max × 600 g, and the screening load G ₁ and the reinforcing load G ₂ can be freely determined in 1/120 steps (5 g) by the changeover switch within the range shown in FIG.

Shown below are the loss fluctuations when the fusion spliced part of the optical fiber core reinforced using this device was subjected to a heat cycle test between -30 ° C and + 60 ° C, and the results of measurement of the initial speed (tensile breaking strength). , As shown in the table below.

From the results in this table, it can be seen that good characteristics can be obtained for both heat cycle loss and connection strength. Moreover, it was confirmed that such good reinforcement can be performed within the time shown in the table.

<Effects of the Invention> As is clear from the above description, the method for reinforcing a fusion spliced portion of a multi-fiber optical fiber according to the present invention is used for continuously screening after fusion-bonded multi-fiber optical fibers are screened. Since the load is reduced and the reinforcing treatment is performed as it is, the core wires do not loosen and come into contact with each other, and the strength does not deteriorate.

Moreover, the screening load G ₁ and the reinforcement load G ₂ can be easily specified by simply operating a changeover switch or the like.

Further, the tension, that is, the screening level can be arbitrarily set according to the number of core wires of the multi-core optical fiber.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of an optical fiber reinforcing device with a tension load device for carrying out the method of the present invention, FIG. 2 is a schematic configuration diagram of the reinforcing device of FIG. 1, and FIG. Fig. 2 is a heating temperature distribution diagram of the reinforcing device, Fig. 4 is a perspective view of the clamp arm fine adjustment device in the tension load device in the device of Fig. 1, and Fig. 5 is a screening load and reinforcing load setting relationship in the device of Fig. 1. 6 (a) and 6 (b) are side views of essential parts of a conventional optical fiber screening device and reinforcing device, respectively.
FIG. 8 is a side view of a main part of a conventional optical fiber reinforcing device with a tension load device, and FIGS. 8 (a) and 8 (b) are perspective views showing the coating removal ends of a single-core fiber and a multi-core fiber, respectively. FIGS. 10 (a) and 10 (b) are plan views showing fusion spliced states of a single-core fiber and a multi-core optical fiber, respectively.
FIG. 3 is a perspective view of a reinforcing member for a single-core fiber and a reinforcing member for a multi-core fiber, respectively. In the drawing, 001 is a multi-core optical fiber, 002 is a bare fiber,
003 is a coating, 004 is a fusion splicing point, 100 is a conventional tension load device, 100a is a tension load device of the present invention, 101 is a clamp part, 1
02 is a clamp armau, 200 is a conventional reinforcing device, 200a is a reinforcing device of the present invention, 201 is a heater, 201a is a heater 1, 201b is a heater 2, 202 is a changeover switch, and 300 is a conventional tension load device. Reference numeral 300a denotes an optical fiber reinforcing device with a tension applying device according to the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiaki Kakii 1 Taya-cho, Totsuka-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industries, Ltd. Yokohama Works (56) Reference JP-A-58-220114 (JP, A) Sho 58-39924 (JP, A)

Claims (1)

[Claims] 1. An optical fiber core wire end portion is gripped around a fusion spliced part of a multi-core optical fiber, and a load load on the optical fiber core wire is adjustable to at least one gripping part side. Along with providing a tension load device for applying a tension, a reinforcing device for reinforcing the optical fiber fusion splicing part is provided, and after finishing the screening by applying tension by the tension load device,
A method for reinforcing a fusion splicing portion of a multi-fiber optical fiber, characterized in that a tension weaker than the tension at the time of screening is applied without making the tension zero and the fusion splicing portion is subsequently reinforced by the reinforcing device. .