JPH09318825A - Non-reflecting terminal part of optical fiber and optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the non-reflecting terminal part of an optical fiber having high reliability with good assembly workability by melting the terminal part of the optical fiber removing a coating from it and forming it into a curved surface curing this part. SOLUTION: The coating 2 at the end of the coated optical fiber 1 is removed by a prescribed length to expose the optical fiber (glass part) 3 consisting of a core and clad. The front end 3b of the exposed glass part 3 is arranged between electrodes 4 and 5 of an arc discharge device and is heated and melted by an arc discharge. The end face 3a of the glass part 3 melted by heating is made spherical by surface tension, by which the end face is curved and a non-reflecting terminal part 3a is formed. There is not need for square cutting the end face 3b of the optical fiber 3 prior to heating. The end face held intact after cutting with nippers, etc., is equally well. The reason thereof lies in that the end face is rounded by the surface tension. In the case of a multiple coated fiber ribbon, the end faces may be simultaneously subjected to the non-reflection terminal treatment. The end face 3a after the non- reflecting terminal treatment is preferably protected with a heat shrinkable tube coated with a thermoplastic adhesive on the inside surface thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-reflective end portion of an optical fiber and an optical module.

[0002]

2. Description of the Related Art For example, light from an optical device is branched into three optical fibers by an optical branching device, and other optical devices are connected to the two optical fibers, but the remaining one optical fiber is connected. You may not connect anything. In such a case, it is necessary to perform non-reflection termination processing on the end portion of the optical fiber to which nothing is connected.

FIG. 5 is a diagram showing a conventional example in which a reflection-free termination treatment is applied to the end portion of an optical fiber (Japanese Patent Laid-Open No. 7-2253).
No. 25).

In this case, a coreless fiber 11 having no waveguide structure is fusion-spliced to the terminal end of the optical fiber 10. The light that has entered the coreless fiber 11 from the optical fiber 10 immediately leaks. The reflection point 12 exists on the end surface of the coreless fiber 11, but the light does not reach there.

Further, in order to perform non-reflective termination treatment on the end portion of the optical fiber, there are the "end face irregular reflection method" (FIG. 6) and the "oblique polishing method" (FIG. 7) as described in the prior art of the publication. .

The end face diffuse reflection method is used for the end face 1 of the optical fiber 10.
It is a method of crushing 3 with pliers or the like.

In the oblique polishing method, the connector 14 is attached to the end of the optical fiber 10 and the end face 15 thereof is oblique (for example, 8
It is a method of polishing to (°). 6 and 7 are views showing another conventional example in which the end portion of the optical fiber is subjected to non-reflection termination processing.

[0008]

However, in the method of connecting the coreless fibers 11 shown in FIG. 5, it is necessary to cut the end faces of the coreless fibers 11 at right angles or to connect them in order to connect the coreless fibers 11. is there. Further, in the method of connecting the connector-terminated coreless fiber to the connector, it takes time and effort to assemble and polish the connector. FIG.
The “end face diffuse reflection method” shown in FIG.
Foreign matter is apt to adhere to No. 3, and when foreign matter adheres to the end face 13, the characteristics are deteriorated. The "oblique polishing method" shown in FIG. 7 requires a process of adhesively fixing the connector 14 to the end of the optical fiber 10 and obliquely polishing the optical fiber terminal together with the connector 14, resulting in a large number of working steps. I have a problem.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to provide an optical fiber non-reflecting terminal portion and an optical module which are easy to assemble and have high reliability.

[0010]

In order to achieve the above object, the non-reflective end portion of the optical fiber of the present invention is formed by melting the end portion of the optical fiber and processing the curved surface.

In addition to the above structure, the non-reflection end portion of the optical fiber of the present invention may have a spherical end surface formed by curved surface processing.

In addition to the above structure, the non-reflection end portion of the optical fiber of the present invention may be formed into a slightly curved end portion by processing a curved surface.

In the optical module of the present invention, the pigtail of the optical fiber connected to the optical module main body is melted and curved.

In addition to the above structure, the optical module of the present invention is
The end face of the pigtail may be formed into a spherical shape by processing the curved surface.

In addition to the above structure, the optical module of the present invention is
The pigtail may be formed into a small bend by the curved surface processing.

With the above structure, a spherical or slightly curved non-reflective end portion can be obtained only by melting the end portion of the optical fiber, so that it is not necessary to attach a connector to the end portion or polish the end portion. Therefore, the assembly workability is good,
Moreover, it is possible to obtain a highly reliable non-reflection end portion of an optical fiber and an optical module.

[0017]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a diagram showing an embodiment of the non-reflective terminating portion of the optical fiber of the present invention. FIG. 1 (a) shows the state before the non-reflective terminating treatment is performed, and FIG. 1 (b). Shows the state after the non-reflective termination treatment.

As shown in FIG. 1A, the optical fiber core wire 1
The coating 2 at the end portion of is removed by a predetermined length to expose the optical fiber (glass portion) 3 including the core and the clad. As shown in FIG. 1B, the exposed tip (end face) 3b of the glass portion 3 is placed between the electrodes 4 and 5 of the arc discharge device and heated and melted by arc discharge. Heated and melted glass part 3
The end surface 3a of 1 is curved by being spherical due to surface tension, and becomes the non-reflection end portion 3a. The end face 3b of the optical fiber 3 before heating does not need to be cut at a right angle, and may be cut by a nipper or the like. This is because the surface tension causes rounding.

The material of the coating 2 of the optical fiber core wire 1 is UV,
Either nylon or silicone may be used, and the number of cords may be any of single-core, 2-core, 4-core tape and the like. In particular, in the case of a multi-core tape core wire, it is also possible to collectively carry out the non-reflection termination treatment. The end surface 3a after the non-reflective termination treatment is preferably protected by a heat-shrinkable tube whose inner surface is coated with a thermoplastic adhesive (usually used to reinforce the fused portion of the optical fiber).

The light propagating through the optical fiber 3 having the non-reflective end portion 3a formed in this way is non-reflective end portion 3a.
The light is emitted to the outside of the optical fiber 3 without being reflected.

FIG. 2 is a diagram showing an optical module to which the non-reflecting end portion of the optical fiber of the present invention is applied.

In the optical module 6 shown in the figure, a plurality of (5 in the figure, but not limited to) two-core tape fibers 8 are respectively connected to the input and output sides of a waveguide type optical coupler 7 as an optical module main body. It is a thing. The end 8a of the two-core tape fiber 8 of the optical module 6 is a pigtail.

The pigtail 8 of such an optical module 6
A case where a non-reflection termination process is performed on a will be described. still,
FIG. 3 is a view showing a modified example of the non-reflection end portion of the optical fiber of the present invention.

The UV coating on the end of the two-core tape fiber of the optical module is removed by about 10 mm to form a pigtail, which is set in an optical fiber fusion machine (not shown). At this time, the tip of the two-core tape fiber is set to slightly protrude from the opposing discharge electrodes of the optical fiber fusion machine. The discharge conditions are almost the same as those for normal fiber fusion, and discharge current 1
5 to 16 mA and a discharge time of 2 to 3 seconds are sufficient.

Under these conditions, the end surface 8 of the pigtail 8a is
When b is subjected to the non-reflective termination treatment, the shape becomes approximately as shown in FIG. The return loss at this time is 50 dB or more. The tip shape of the pigtail 8a of the two-core tape fiber 8 before the electric discharge heating does not need to be formed into a right circular cylinder, and may be an irregular surface cut by a nipper or the like. This is because the surface tension of the molten glass causes it to be processed into a smooth curved surface. Therefore, only the removal of the coating of the optical fiber is required as the pre-processing step in the non-reflection termination treatment.

Since the glass is exposed at the end of the optical fiber after the non-reflection termination treatment, it is preferable to cover the fusion-bonded portion with a tube in order to protect it from scratches and dust. As a simple method, a heat shrinkable tube may be simply covered.

FIG. 4 is a view showing another embodiment of the non-reflection end portion of the optical fiber of the present invention.

As shown in the figure, the side surface of the optical fiber 3 from which the coating 2 of the optical fiber core wire 1 has been removed is heated and curved into a small bend. The curved portion 3c is a non-reflection end portion. Even if the optical fiber 3 is formed in this way, the same effect as that of the non-reflection end portion 3a of the optical fiber shown in FIG. 1 can be obtained. However, in this case, when the reinforcing tube is covered, an unreasonable force may be applied to the optical fiber 3 and the optical fiber 3 may be broken.

In the above, in the conventional non-reflective terminating treatment of the optical fiber, for example, in the case of the system using the connector, the connector had to be adhesively fixed to the optical fiber terminal and the end face with the connector had to be obliquely polished. On the other hand, according to the present invention, it is sufficient to discharge and heat the terminal for several seconds, and the workability can be greatly improved as compared with the prior art. In addition, since the connector is not used, the material cost is low, and an economical non-reflective termination processing section can be obtained in addition to the improvement of workability.

Further, when applied to an optical module, it is possible to save a great amount of space by reducing the size of the reinforcing tube in the case accommodating the optical module.

[0032]

In summary, according to the present invention, the following excellent effects are exhibited.

(1) By melting the end portion of the optical fiber from which the coating has been removed and processing the curved surface, it is possible to provide a highly reliable and non-reflective end portion of the optical fiber that is easy to assemble. it can.

(2) By melting the end portion of the pigtail-shaped optical fiber from which the coating has been removed and processing the curved surface, it is possible to provide an optical module with good assembly workability and high reliability.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a non-reflection end portion of an optical fiber according to the present invention.

FIG. 2 is a diagram showing an optical module to which the non-reflecting end portion of the optical fiber of the present invention is applied.

FIG. 3 is a view showing a modified example of the non-reflection end portion of the optical fiber of the present invention.

FIG. 4 is a diagram showing another embodiment of a non-reflection end portion of the optical fiber of the present invention.

FIG. 5 is a diagram showing a conventional example in which a reflection-free termination treatment is applied to a termination portion of an optical fiber.

FIG. 6 is a diagram showing another conventional example in which a reflection-free termination treatment is applied to the termination portion of an optical fiber.

FIG. 7 is a diagram showing another conventional example in which the end portion of the optical fiber is subjected to non-reflection termination processing.

[Explanation of symbols]

 2 coating 3 optical fiber 3a non-reflective end (end face) 3c non-reflective end (curved part)

Claims (6)

[Claims] 1. A non-reflective end portion of an optical fiber, characterized in that the end portion of the optical fiber is melted and curved. 2. The non-reflection end portion of the optical fiber according to claim 1, wherein the end surface is formed into a spherical shape by the curved surface processing. 3. The non-reflection end portion of the optical fiber according to claim 1, wherein the end portion is formed into a small bend by the curved surface processing. 4. An optical module, characterized in that a pigtail of an optical fiber connected to an optical module main body is melted and curved. 5. The optical module according to claim 4, wherein the end surface of the pigtail is formed into a spherical shape by the curved surface processing. 6. The optical module according to claim 4, wherein the pigtail is formed into a small bend by the curved surface processing.