JPH0242204B2 - - Google Patents

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 low splice loss and high reliability fusion splicing method is effective for permanently splicing optical fibers, especially single mode optical fibers. However, current fusion splicing technology is still insufficient for connecting submarine optical cables that require absolute reliability or long life.

The most important consideration in the reliability of optical fiber connections is the breakage of the optical fiber at the connection.

As a result of various studies on the causes of this breakage, it has become clear that the main cause of the breakage is due to scratches on the surface of the optical fiber.

The processes that cause surface scratches in the fused state include (1) the primary coating removal process, (2) the cutting process, and (3) the optical fiber gripping process during connection.

Here, considering the method for preventing surface scratches in each step, in (1) the primary coating removal step, a solvent is used instead of mechanical removal. Regarding the gripping of the optical fiber in (3), surface scratches can be prevented by gripping the coated part without gripping the bare fiber part, but in the cutting process of (2), the conventional method If the primary coating is removed in this way, it is difficult to avoid surface scratches during cutting. Therefore, one possible method for preventing surface scratches is to remove the primary coating after cutting, but this method involves applying cutting scratches to the optical fiber surface from above the primary coating, which may cause damage to the primary coating. There is a problem in that cutting conditions vary depending on thickness, hardness, etc., making it difficult to obtain good cuts.

[Disclosure of the Invention] The present invention aims to prevent scratches on the surface of the optical fiber when the optical fiber is cut in such conventional fusion splicing of optical fibers. After removing the primary coating, a cut is made at the end of the primary coating and cut, and the primary coating is chemically removed to a length necessary for fusion splicing the optical fibers again to perform fusion splicing.

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 set in an optical fiber cutter 3.
Up to this point, the method is the same as the conventional construction method. Next, using the cutting blade 4, a cutting scratch 5 is applied to the surface of the optical fiber 1 at the end of the primary coating 2, and then bending stress is applied to the optical fiber 1 to cut the optical fiber 1 from the cutting scratch 5 (second figure).

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. Both optical fibers 1 which have been cut and whose primary coating 2 has been removed in this manner are shown in FIG.
Hold each part of the primary coating 2 in the fusion splicer 8
After aligning the axes of both optical fibers 1, the abutting portions 9 are fused and spliced using heat generated by arc discharge 10.

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, by employing the fusion splicing method of the present invention, good fusion splicing can be performed without causing any surface scratches 6 on the optical fiber 1.

[Effects] As explained above, according to the present invention, there is no surface scratch on the optical fiber, so as already mentioned,
The cause of optical fiber breakage is eliminated, and the tensile breaking load at the connection part is several times greater than that of conventional methods.
Reliability is greatly improved.

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

[Brief explanation of the drawing]

Figures 1 to 3 are schematic explanatory diagrams of the cutting process;
FIG. 4 is an explanatory diagram of fusion splicing. DESCRIPTION OF SYMBOLS 1... Optical fiber, 2... Primary coating, 3... Cutting device, 4... Cutting blade, 5... Cutting scratch, 6... Surface scratch, 7... Cut end, 9... Butting part, 10... ...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 primary coating and cutting, and the length required for fusion splicing of the optical fiber is cut again. A method for fusion splicing optical fibers, characterized in that the primary coating is chemically removed before fusion splicing.