JPH063551A - Optical fiber fusion splicing method - Google Patents

Abstract

PURPOSE:To obviate the generation of connection loss by the mis-alignment of optical axes and to assure surface protection by forming thin films of metals, ceramics or carbon on the surfaces of glass fibers from which the coatings at the front ends of the optical fibers are removed, then butting the ends of the optical fiber and fusion splicing the fibers. CONSTITUTION:The coatings 3 at the ends of the optical fibers 1 are first removed and the front ends are cut, by which mirror finished surface are obtd. These optical fibers 1 are then put into a chamber 11. On the other hand, a gaseous raw material of carbon is introduced into the chamber 11. A CO2 laser beam is condensed from a light source 8 and the surface of the glass fiber 2 is irradiated with this laser beam through a window 10 of ZnSe and is heated, by which a carbon thin film 4 is formed thereon. The carbon thin films 4 are respectively formed similarly on the other fibers as well. The end faces of the optical fibers 1 are disposed to face each other and the parts of the thin films 4 are placed on the grooves of an axis alignment base and are fixed by clampers. Four pieces of the fibers are simultaneously fusion spliced by a discharge means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fusion splicing method for optical fibers capable of preventing surface scratches and facilitating axial alignment.

[0002]

2. Description of the Related Art Heretofore, when an optical fiber was connected, minute scratches were formed on the surface of the glass fiber, causing breakage. Therefore, the coating of the optical fiber is removed to expose the glass fiber, an ultraviolet curable resin is applied to the surface of the glass fiber to form a protective coating having a thickness of several microns, and then fusion splicing is performed (JP 62-240911).

[0003]

In the conventional method, an ultraviolet curable resin was used as a protective film, but in order to achieve the purpose of protection with this kind of material, at least 3
A thickness of 4 μm or more was required. By the way, in the method in which the glass fiber is placed on the V-groove and the fusion is spliced by aligning the axes with the cladding outer diameter as a reference, the coating is thick, and when variations occur, the axes are misaligned and the splice loss increases. There was a problem of doing. Further, in the case of connecting a multiplicity of tape-shaped optical fibers together, since the fibers are close to each other, it becomes more difficult to apply the ultraviolet curable resin evenly, and the conventional technique is applied to the tape-shaped optical fibers. It didn't come.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a fusion splicing method of an optical fiber for solving the above-mentioned problems, which is characterized in that the coating at the tip of the optical fiber is removed to expose the glass fiber. Then, after forming a thin film of metal, ceramic or carbon on the surface of the glass fiber,
In this method, the ends of the optical fiber are abutted against each other and fusion-spliced.

This method can obtain a great effect for a multi-core tape-shaped optical fiber as well as a single-core optical fiber.

As the best mode of the present invention, the glass fiber is placed in an atmosphere of carbon source gas, the surface of the glass fiber is irradiated with a CO ₂ laser to form a carbon thin film, and then fusion splicing is performed. is there. After performing the fusion splicing described above, by further forming a thin film made of the same kind of material as the above thin film in the connection part and the vicinity thereof,
It is possible to ensure the protection of the surface of the glass fiber.

[0007]

According to the present invention, since a metal such as nickel, a ceramic such as SiN or carbon is used as the protective film for the glass fiber, the adhesion to the glass fiber is high, so that the film thickness can be reduced to about 0.5 μm. It can have a sufficiently hermetic effect. That is, when the glass fiber provided with the thin film is fixed on the V groove, it is possible to prevent the fiber surface from being scratched by the contact with the V groove and the clamp. Further, since the film thickness can be formed thin, even if the film thickness varies, the connection loss is hardly affected. When a thin film is once formed and then fusion-bonded, the thin film may be peeled off by the heat at the time of fusion. Therefore, after fusion bonding, a thin film is formed again.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical fiber fusion splicing method according to the present invention will be described below with reference to the accompanying drawings. FIG. 3 is a cross-sectional view of a four-core tape-shaped optical fiber used for the connection of the present invention, 2 is a glass fiber, and 3 and 3'are coatings made of an ultraviolet curable resin.

First, the coating 3 on the end of the optical fiber 1
3'is removed and the tip is cut to obtain a mirror surface. 1 is placed in a chamber 11 shown in FIG. 1, while carbon source gas is introduced into this chamber. CO ₂ laser light is collected from the light source 8 and irradiated on the surface of the glass fiber 2 through a ZnSe window, and the temperature is about 1000 ° C.
Then, the carbon thin film 4 is formed. Similarly, a carbon thin film of about 0.5 μm is formed for each of the other fibers, the ends of the optical fibers are made to face each other, and the thin film 4 is placed on the groove 6 of the alignment table 5 shown in FIG. Fix with clamper 7. Next, four fibers were fusion-spliced together by a discharge means (not shown).

When the characteristics of 10 optical fibers connected by the above-mentioned method were examined, the average value of the tensile breaking strength was 6.3 kg and the average value of the connection loss was 0.05 dB. On the other hand, when the same optical fiber was fusion-spliced by the conventional method, the average value of the tensile breaking strength was 6.2 kg and the average value of the connection loss was 0.20 dB.

The case where the thin film is formed of carbon has been described above. In addition to this, for example, SiN, BN, Ti.
Ceramics such as N are deposited by the CVD method into Ni, Al, Au.
The same effect can be obtained by forming a metal such as by a sputtering method.

[0012]

EFFECTS OF THE INVENTION By covering the ends of the optical fibers that are fusion-spliced to face each other on the glass fiber with a thin film of carbon or the like, even if the film thickness is reduced to 1 μm or less, Since the adhesion is strong, it can have a sufficient hermetic effect. Further, since the film thickness can be formed thin, the connection loss due to the deviation of the optical axis hardly occurs. Furthermore, since the thin film is formed again after the above-described fusion splicing, the surface protection of the connecting portion can be ensured.

[Brief description of drawings]

FIG. 1 is an explanatory diagram according to an embodiment of a fusion splicing method for optical fibers of the present invention.

2 is the same as FIG.

FIG. 3 is a cross-sectional view of a 4-core tape-shaped optical fiber.

[Explanation of symbols]

 1: Tape-shaped optical fiber 2: Glass fiber 3: Coating 4: Thin film 5: Alignment table 6: V groove 7: Clamper 8: Light source 9: Lens 10: Window 11: Chamber

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Nobuyuki Yoshizawa 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (4)

[Claims] 1. A glass fiber is exposed by removing the coating on the end of the optical fiber, and a thin film of metal, ceramic or carbon is formed on the surface of the glass fiber, and then the ends of the optical fiber are butted to each other and fusion-spliced. An optical fiber fusion splicing method, comprising: 2. The fusion splicing method for optical fibers according to claim 1, wherein the optical fiber is a multi-core tape-shaped optical fiber. 3. The optical fiber according to claim 1, wherein the glass fiber is placed in an atmosphere of carbon source gas, and the surface of the glass fiber is irradiated with a CO ₂ laser to form a carbon thin film. Fusion splicing method. 4. The glass fiber is exposed by removing the coating at the end of the optical fiber, a thin film of metal, ceramic or carbon is formed on the surface of the glass fiber, and then the ends of the optical fiber are butted to each other and fusion-spliced. Then, a fusion splicing method for an optical fiber, further comprising forming a thin film made of the same material as the thin film on the connection part and its vicinity.