JPS60243607A - Method for connecting optical fibers by welding - Google Patents

Abstract

PURPOSE:To obviate surface grazing and to eliminate the cause for breakage by the procedure consisting of removing and cutting the primary covering of fibers and removing chemically the primary covering. CONSTITUTION:The primary covering 2 of the optical fiber 1 is mechanically or chemically removed and is set to a cutter 3. A score 5 is given by a knife 4 to the surface of the covering 2 and the fiber is bent and cut. The fiber 1 is grazed 6 on the surface by contact with the cutter 3, but the cut end 7 is specular and perpendicular. The fiber end is in succession dipped into a hot sulfuric acid and the primary covering 2 is removed by the required length. Two pieces of such optical fibers 1 are aligned and the butt parts 9 are welded and connected by an arc discharge 10. The fibers 1 are satisfactorily welded and connected without surface graze 6 at all according to the above-mentioned constitution.

Description

[Detailed description of the invention] [Technical field] The present invention relates to a method for fusion splicing optical fibers.

[Background Art and Problems] A fusion splicing method with low splice loss and high reliability is effective for permanently splicing optical fibers, especially single mode optical fibers. However, when it comes to connecting submarine optical cables that require absolute reliability or long life, current fusion splicing technology still places the most importance on the reliability of optical fiber connections. This is a break in the optical fiber.

As a result of various studies on the causes of this rupture, we found that
It has become clear that the main cause of breakage is surface scratches on the optical fiber.

Looking at the process of creating surface scratches during fusion splicing, (1)
- Next coating removal process, (2) cutting process, (3) optical fiber gripping process during connection, etc.

Here, if we consider how to prevent surface scratches in each process, <1
) In the subsequent coating removal step, a solvent is used instead of mechanical removal. Regarding gripping the optical fiber in (3), it is possible to prevent the surface from being scratched by gripping the coated part without gripping the bare fiber part, but in the cutting process (2), unlike the conventional method, the primary coating If it is removed, it is inevitable that the surface will be scratched during cutting. Therefore, one possible method for preventing surface scratches is to remove the secondary coating after cutting, but this method would cause cutting scratches on the optical fiber surface from the primary coating. The cutting conditions vary depending on the thickness and hardness of the material, and there is a problem that good cutting cannot be obtained.

[Disclosure of the Invention] The present invention aims to prevent scratches on the optical fiber surface when the optical fiber is cut in such conventional fusion splicing of optical fibers, and the primary coating on the distal end side of the optical fiber from the cutting position is After removing the coating, cut the coated end with cutting scratches and cut it again to the required length for fusion splicing the optical fiber.
- The second coating is chemically removed and fusion spliced.

The implementation of the present invention will be explained below with reference to the drawings.

Figures 1 to 3 are schematic diagrams showing the process of cutting an optical fiber, and Figure 4 is a schematic diagram showing how to hold the optical fiber when the cut optical fiber is fused with a fusion splicer. be.

The primary coating 2 of the optical fiber 1 is removed mechanically or chemically, and the optical fiber 1 is inserted into an optical fiber cutter 3.

Up to this point, it is the same as the conventional construction method. Next, using the cutting blade 4, a cutting flaw 5 is given to the surface of the optical fiber 1 at the second end of the second coating, and then bending stress is applied to the optical fiber l to cut the optical fiber l from the part of the cutting flaw 5 (first Figure 2).

In this process, countless surface scratches 6 are formed on the surface of the optical fiber 1 that comes into contact with the cutter 3, but there is no problem because the portion with the surface scratches 6 is discarded after cutting.

Further, since the cut end 7 is cut after removing the primary coating 2, a mirror surface and a right angle can be obtained as before.

Next, the cut optical fiber 1 end is immersed in hot sulfuric acid or the like to remove the primary coating 2 to a required length (FIG. 3).

By performing the steps of removing the primary coating, cutting, and chemically removing the primary coating as described above, there is no surface that touches the surface of the optical fiber 1, so the number of surface scratches 6 becomes zero. As shown in FIG. 4, both optical fibers 1 having been cut and having their primary coatings 2 removed are held in a fusion splicer 8L7 with the primary coating 2 removed, and the axes of both optical fibers 1 are aligned. After that, the butt portions 9 are fused and spliced by heat generated by arc discharge IO.

Even in this fusion splicing step, since there is no part that touches the surface of the optical fiber 1, the splicing can be completed without any damage.

As described above, when the fusion splicing method of the present invention is adopted, good fusion splicing can be performed without causing any surface scratches 6 on the optical fiber 1.

[Effects] As explained below, according to the present invention, there are no surface scratches on the optical fiber, so as already mentioned, there are no factors causing the optical fiber to break, and the tensile breaking load at the connection part is also lower than that of the conventional method. It is several times larger and has much higher reliability.

It also guarantees a long life and enables connections suitable for submarine optical cable connections.

[Brief explanation of the drawing]

1 to 3 are schematic explanatory diagrams of the cutting process, and FIG. 4 is an explanatory diagram of the fusion splicing. DESCRIPTION OF SYMBOLS 1... Optical fiber, 2... Secondary coating, 3... Cutter, end, 9... Butt part, 1O... Arc discharge.

Claims (1)

[Claims] (1) In the optical fiber fusion splicing method, after removing the primary coating on the tip side from the cutting position of the optical fiber, cutting scratches are given to the end of the second coating and cutting, and the optical fiber is fusion spliced again. A method for fusion splicing optical fibers, characterized in that the primary coating is chemically removed to a required length before fusion splicing.