JPS60205404A - Method for connecting coated optical fibers and method for reinforcing juncture of coated optical fibers - Google Patents

Abstract

PURPOSE:To eliminate the factor to deteriorate the strength in the juncture of a pair of optical fibers and to improve the mechanical strength thereof by forming a film on the outside circumference of the fibers of which the end faces are held butted to each other and subjecting the juncture thereof to a surface treatment for the required time by a corrosive soln. which dissolves the fibers after welding. CONSTITUTION:Coatings 2A, 2B are removed from the ends of a pair of coated optical fibers 1A, 1B to expose bare optical fibers 3A, 3B. The exposed parts are dipped in a soln. of insulating urethane varnish dissolved in a solvent such as glycol ether or the like and is then pulled up and dried to form the hard film of the varnish on the outside circumference. The top end sides are cut perpendicularly to make adequate butt end faces 5A, 5B. The end faces are butted to each other and are welded and connected by arc discharge via a pair of discharge electrodes 6M, 6N. The juncture 7 is dipped in a corrosive soln. 8, is taken out thereof, is cleaned and is further dried; thereafter the outside circumference of the bare optical fibers 3A, 3B including the juncture 7 is immediately coated by urethane resin varnish.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for connecting coated optical fibers, a coated optical fiber,
Concerning methods for strengthening bar connections.

As a method for permanently splicing optical fibers, a method is often employed in which the ends of the -i optical fibers are brought into a butt state and each end is fusion spliced by arc discharge or the like.

This method is an effective means in that the connection loss at the connection can be reduced, and the average strength when tensile force is applied to the connection is extremely small, about 9/10.
There is a need for an investigation into the problem with a strength of 12 and a method for solving it.

In the present invention, in proposing a fusion splicing method for optical fibers and a method for strengthening the splicing portion, the above-mentioned problems are solved as follows.

Generally, in this type of fusion splicing, the ends of a pair of broken optical fibers to be spliced are removed with a sheathing removal tool to leave a part of the optical fiber exposed, and the exposed portion is Completely wipe off any remaining cracks with absorbent cotton moistened with an organic solvent such as acetone, then cut the tips of these optical fibers almost vertically and remove the butt ends with proper +F. After that, both ends are butted! A pair of discharge electrodes
The two optical fibers are fusion spliced by arc discharge or laser heating, etc. 1. When splicing in such cases, the breakage is eliminated. A serious wound occurred -L
L, these minute scratches will deteriorate the strength of the connection.

In addition, during handling, foreign matter such as dust in the air accumulates on the surface of the exposed part that has been cleaned with an organic solvent such as A7/L'. If the two butted ends are heated and fused using arc discharge or laser heating with foreign matter still attached to the surface, these foreign matter will burn onto the surface of the fused part or get mixed into the optical fiber.
This also deteriorates the strength of the connection.

On the other hand, during heat fusion, there are parts that are heated and parts that are hardly heated in the exposed part mentioned above, and the thermal strain caused by the temperature difference at this time causes minute cracks on the surface of the exposed part. occurs in

As described above, it can be said that these various causes cause problems in the strength of the optical fiber connection portion.

An object of the present invention is to provide an optical fiber connection method that can address the above-mentioned problems and effectively eliminate these mixed strength deterioration factors.

Furthermore, another object is to provide a processing method for strengthening connections made by the method.

In order to achieve the above object, the present invention removes the coating at the end of a coated optical fiber to expose the bare optical fiber, and provides a pair of end faces of coated optical fibers by applying a hard coating to the outer periphery of the bare optical fiber. are brought into a butt state, and the respective ends in the same state are fused to each other to form a connection part.

In order to achieve yet another object, the ends of a pair of coated optical fibers are obtained by removing the coating at the ends of the coated optical fibers to expose the bare optical fibers, and applying a hard coating to the outer periphery of the bare optical fibers. The parts are butted, and each part is in the same state!
;Mo: The joint formed by mutually fusing the optical fibers is surface-treated with a corrosive solution for a required period of time to dissolve the optical fiber.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In the figure (where IA and IB are a pair of coated fibers to be connected), these pair of Yuzu 1M optical fibers IA and I
The end portions of the optical fibers 1j2A and 2B are removed using a deforming tool (not shown) to expose the bare optical fibers 3A and 3B.
The exposed portions of 4U2A and 2B are removed by wiping the exposed portions of 4U2A and 2B with a degreasing agent χJi1 that has been degreased with a solvent such as acetate/etc. After that, exposed r4! optical fiber 3
Dissolve parts A and 3 B in a solvent such as glycol ether.
(+!4 urethane soaked in 7-layer & varnish solution:
Thereafter, they are pulled out and dried to form a hard varnish skin on the outer periphery of the bare optical fibers 3A and 3B, as shown in FIG.

+6. In this example, a urethane-based insulating varnish is used as the coating formed on the outer periphery of the bare optical fibers 3A, :3I3, but the hard coating is not limited to a urethane-based insulating varnish; The bare optical fibers 3A and 3B on which the hard coatings 4A and 4B have been formed as described above may be made of a resin, an ultraviolet curing resin, or a 7-rankanobbling agent. Proper abutting end 5 is obtained by cutting almost vertically as shown in Figure 3.
A and 5B are made, and then both butt end faces 5 are made as shown in Figure 4.
A, 5B are brought into contact with each other, and the two bare beams 3A, 313 are fused and connected by arc discharge via a pair of discharge electrodes 6M, 6N.

After the fusion splicing, the joint 7 is immersed in a corrosive solution 8 for the required time as shown in FIG.

This corrosive solution has chemical properties that should dissolve the bare optical fibers 3A and 3B, and specifically, it is hydrofluoric acid, a mixed aqueous solution of hydrofluoric acid and strong acid (sulfuric acid, nitric acid, hydrochloric acid), etc. An aqueous ammonium fluoride solution, a mixed aqueous solution of hydrofluoric acid and an aqueous ammonium fluoride solution, etc. can be used as the corrosive solution 8.

5-5, the connecting part 7 is immersed in the corrosive solution 8, and after the surface is diluted with the stock solution 8 for the required time to complete the prescribed treatment, the connecting part 7 is removed from the corrosive solution 8. After washing with water or alkaline washing, and further drying, the bare optical fiber 3 A1, 1B including the connection part 7 is removed.
Coding is carried out on the outside of J1J, J by a urethane resin face (directly above). The coating is carried out, for example, by forming a hard skin pattern 1 described above, applying a solution of urethane insulating varnish &CIA'r+', and then drying it in the same manner as in method 4-a). It should be noted that it is desirable that the outer periphery of the bare optical fibers 3A and 3B of the connecting portion 70 be coated with the same material as the hard coating formed on the closed optical fibers 3A and 3B before fusion. There is no peace of mind.

J゛J, As mentioned above, in the present invention, there is no naked light driver;
3A1, 3■3 + (Before the fusion splicing, a PdK hard film is formed on the outside of each bare optical fiber 3A, 3B, so the effect of the film will cause the bare optical fiber 3A, Foreign matter is less likely to adhere to the surface of 3B, and surface scratches can be prevented from occurring during handling.

Therefore, when such bare optical fibers 3A and 3B are fusion-spliced by arc discharge or laser heating, no foreign matter is baked onto the surface of the bare optical fiber or mixed into the optical fiber, and furthermore, there is no possibility that foreign matter will be burned into the surface of the bare optical fiber or mixed into the optical fiber. Since the connection is not made with any scratches present, a decrease in strength at the connection portion 7 can be prevented.

In addition, after fusion splicing, the surface of the splicing portion 7 is treated for the required time using a corrosive solution of 1.8 K that dissolves the optical fibers 3A and 3B. Even if minute cracks occur, they are erased or smoothed by the dissolving action of the corrosive solution 8 described in -F.

Therefore, it is possible to eliminate the decrease in strength caused by thermal strain during fusion splicing.

Ma/, -, l crystal ii! Both bare fibers 3A and 3B are surface-treated with Ilt'l solution 8, and then coated with resin on the surface of Id. ] ゛It prevents new surface scratches from occurring on AIVA 3A, 3B, so it is less corrosive.
Strong retention obtained by solution 8 1
, ・〕Next, a specific example will be described with (・).

Outer diameter of quartz-based Gl type optical fiber 3”A, 3B 25
/l (core diameter 50 trm), primary coating outer diameter of silicone resin is 400 tons, and nylon 12
[Taro f after coating! l OO14m) In the optical fibers IA and IB, the ends 12Δ and 2B of these 11 are removed using a known stripping device, and the stripped optical fiber 3A, ; The outer periphery of 3B was wiped with an acetone-impregnated wiper (absorbent cotton), and then the exposed portions of bare optical fibers 3A and 3B were dipped in a solution of urethane insulating varnish dissolved in a glycol ether solvent. After drying, hard films 1A and 4B were formed.

Next, optical fibers 3A and 3 having the above coatings 4A and 4B are prepared.
These were set in an optical fiber cutter and cut vertically so that the length of B was about 301 m+, and then each of the optical fibers 3A and 3B was set in a fusion splicer and fusion spliced.

The average tensile strength (average value of 20 fibers) of the optical fiber connections fused and spliced in this manner was 80 kg/*j.

Furthermore, after that, the connection part 7 was added with hydrofluoric acid 4, 5 +
nnl/l and sulfuric acid 45 n1o1/l IT)
Vc in corrosive solution 8 consisting of mixed aqueous solution 1.5 minutes to 10
After soaking for a minute, the connection 7 was piloted and dried.

The average tensile strength (average value of 20 fibers) of the fiber connections treated by this method was IBoky/-.

Of course, in the conventional example in which no measures are taken, the average tensile strength is about so kg/i#l, as described above.

The method of the present invention connects rj, y to the bend described below, brings the end faces of the saw blades into butt state, and fuses each end face in the same state to phase r7- to form a connection. The forming method is characterized by forming a film on the outer periphery of each optical fiber before the above-mentioned fusion, and after the above-mentioned fusion, the surface of the connection part is treated for a required period of time with a corrosive solution that dissolves the optical fiber. Therefore, by performing two types of processing before and after the connection, it is possible to eliminate the deterioration of the strength of the connection part, and the mechanical strength of the fiber connection part is greatly improved.

[Brief explanation of drawings]

Figures P,'+,+Figures 2 through 5 are explanatory diagrams schematically illustrating an embodiment of the method of the present invention in the order of j. +A, IB/coated optical fiber, 2A, 2Bv+Ia,:
+ A, 3 B Optical F Iha, 4A1. I B butt end surface, 6M, 6N discharge electrode, 7 connection 11μ, 8 corrosive solution Fig. 2 4At4B11r3A[3Bl Fig. 3

Claims (1)

[Scope of Claims] il+ A pair of wave-shaped optical fibers each formed by removing a wave cut at a fiber terminal to expose a closed optical fiber and applying a hard coating to the outer periphery of the closed optical fiber are butted against each other. 1. A method for easily connecting nine fibers to be tested, characterized in that each end face in the same state is fused to a phase Li to form a connection part. (2) Remove the cracks in the optical fiber terminals to expose the bare optical fibers, and add (
i! I! The end surfaces of the 11Q coated leather are brought into a butt state, and the joints formed by fusing the end surfaces of the circular shape and the book to each other are glued for the required time. A method for strengthening coated optical fiber joints, which is characterized by surface treatment with a corrosive solution that dissolves the optical fiber.