JP2947301B2 - Method of manufacturing optical fiber fused coupler and equipment used for manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fused optical fiber coupler, and more particularly, to a method of manufacturing an optical fiber fused coupler for fixing an optical fiber, heating, melting, and extending the same, and for manufacturing the same. Related to the equipment used.

[0002]

2. Description of the Related Art Optical fiber fused couplers are used to split light.
It is an optical device that has the function of merging. The function of branching and merging light is realized by reducing the core diameter of the optical fiber and bringing the cores close to each other so that the electrolytic distribution of light passing through the optical fiber reaches the close optical fiber.
An ordinary optical fiber fusion type coupler is manufactured by arranging a plurality of optical fibers so that their side surfaces are in contact with each other, and then heating and melting and stretching the contact portions of the optical fibers. When manufacturing this optical fiber fused coupler,
By controlling parameters such as the heating temperature of the optical fiber, the length of the fusion zone, and the stretching speed, it is possible to obtain optical fiber fused couplers having various branching ratios.

[0003] Optical fiber fused type couplers are used in a wide variety of applications, such as various measuring instruments and optical fiber communication, and have been put to practical use in a wide field using optical fibers. In the future, a large amount of fused optical fiber couplers is expected to be used as a key device for performing single wavelength bidirectional transmission in subscriber optical fiber communication. Important requirements for optical devices used in subscriber optical fiber communication systems include:
It is inexpensive and excellent in mass productivity. For this reason, an inexpensive optical fiber fused coupler with good productivity is required, and how to manufacture the optical fiber efficiently is an important issue.

[0004] A method of manufacturing a conventional optical fiber fused coupler will be described below with reference to FIG.

[0005] First, a plurality of optical fibers 8 from which the coating has been removed from the central portion are arranged side by side so that the portions from which the coating has been removed can come into contact with each other (see FIG. 3A).

Normally, fusion of a single mode fiber is performed by
As will be described later, the two optical fibers are stretched in a parallel state while keeping the side surfaces in contact. Since the state of the optical fiber at this time is also important for the characteristics of the coupler, it is necessary to arrange the optical fiber with high accuracy so that the side surfaces are surely in contact with each other.

First, a plurality of optical fibers 8 in which the portions from which the coating has been removed are arranged in parallel are arranged, for example, in Japanese Unexamined Patent Publication No.
It is set in an optical fiber coupler manufacturing apparatus as described in JP-A-232515.

The optical fiber 8 is sandwiched by the fixing member 9 of the optical fiber coupler manufacturing apparatus so that the optical fiber 8 arranged in parallel with the optical fiber coupler manufacturing apparatus is surely brought into contact with the optical fiber coupler manufacturing apparatus. 8 is fixed (see FIG. 3B).

After confirming that the optical fiber 8 has been securely fixed, the optical fiber contact portion 10 is heated by the burner 11 (see FIG. 3C).

Optical fiber contact portion 1 sufficiently heated and melted
At 0, the cladding of the adjacent optical fiber 8 is fused.

Further, the melted optical fiber 8 can be easily drawn only by pulling the melted portion to both sides.

The stretching is performed by moving the fixing members 9 on both sides in the opposite direction along the axis of the optical fiber 8 and pulling the fusion portion.

The stretching reduces the clad diameter and the core diameter of the optical fiber contact portion 10 (see FIG. 3D).
As a result, the cores are close to each other, and the electrolytic intensity of light propagating through the core of the optical fiber 8 reaches the core of the adjacent optical fiber 8. As a result, the optical fiber fusion portion realizes the function of optical branching / coupling as an optical coupler.

The fused optical fiber coupler thus fused is usually packaged for use as an optical device. The fusing part is protected from external force, humidity, etc. by packaging.

[0015]

In the conventional optical fiber fused type coupler, the stretching of the optical fiber, which is considered to be the most important for obtaining stable optical coupler characteristics, is performed by the fixing member 9 which holds down the optical fiber. Is moved along the axis of the optical fiber 8.

However, when the optical fiber is fixed by the fixing member 9, the holding state varies, and a non-uniform force is likely to be applied to the optical fiber 8 during stretching. When a non-uniform force is applied to the optical fiber 8 during drawing, the optical fiber fusion portion bends, resulting in twisting (see FIG. 4).

As described above, in the conventional optical fiber fused type coupler, when the optical fiber is stretched, the optical fiber fused portion bends and twists, so that the desired performance cannot be obtained in many cases, and the production yield is low. There is a problem of bad.

In order to obtain a desired branching ratio with good yield, it is necessary to always stabilize the fusion / stretching step. However, in the conventional optical fiber fused coupler, the fixing member 9 is not used.
The fixing of the optical fiber 8 is not complete, and the contact state of the fused portion is not stable.

Therefore, a stable branching ratio cannot be obtained, and the amount of stretching must be adjusted by each coupler.
The amount of stretching is adjusted by stopping the stretching when a proper branching ratio is reached while constantly inputting and monitoring light during stretching.

However, to monitor the branching ratio,
Light must be incident on the optical fiber from one side and emitted from the other side and input to the optical power meter, requiring terminal treatment such as cutting the end of the optical fiber. Terminal processing requires precise work, and requires work skills and a great deal of man-hours. As a result, productivity is significantly reduced,
There is a problem that mass production is not possible.

Further, in order to stretch the optical fiber straight with as uniform a force as possible, a high-precision manufacturing apparatus is required. However, such a high-precision manufacturing apparatus is very expensive, and there is a problem that the maintenance of the equipment also takes time.

In order to use the manufactured optical fiber fused coupler as an optical component, it is necessary to package the fused optical fiber.

In the conventional packaging, the fused optical fiber is removed from the fusion device, and a process such as passing the fused portion of the optical fiber through a glass pipe or solidifying with a resin or the like is performed.

However, in these methods, since the outer diameter becomes thinner and the fused portion of the optical fiber which has become weaker than the ordinary optical fiber must be handled in a bare state,
Workability is poor, and many defects due to breakage of the optical fiber occur during the packaging operation.

An object of the present invention is to provide a method of manufacturing an optical fiber fusion coupler in which the stretching of an optical fiber is stabilized and the workability at the time of fusion and packaging is improved.

Another object of the present invention is to provide a highly reliable fused optical fiber coupler having high productivity and stable characteristics.

[0027]

The fused optical fiber coupler of the present invention does not require a high-precision manufacturing apparatus, and has a structure in which an optical fiber can be easily fused and drawn. Particularly, in order to stabilize the stretching, an alignment hole is provided in a pair of fixing members for fixing the optical fiber, and a pair of alignment rods are inserted into the alignment hole. With this structure, stretching can be performed without applying uneven force to the fused portion of the optical fiber.

As a manufacturing sequence for stable drawing, first, a plurality of optical fibers are brought into contact, and both ends of the contacted portion are fixed to the surface of a fixing member connected by alignment rods, and the optical fiber contact portion is heated. . When the optical fiber is heated and melted, the fixing members are pulled in opposite directions to each other to stretch the optical fiber. By pulling the fixing member fixing the optical fiber, it is possible to apply the same tension to all the optical fibers starting from the fixing point of the optical fiber,
In addition, the optical fiber can be reliably straightened.

In the stretching step, the tension applied to the optical fiber can be made uniform without using a high-precision manufacturing apparatus as in the prior art. Therefore, the optical fiber can be stably drawn without bending or twisting of the optical fiber. As a result, a fused optical fiber coupler having good characteristics can be stably manufactured.

The fixing member for fixing the optical fiber may be provided with a groove for guiding the optical fiber so that the optical fiber can be easily arranged. By providing the groove for the optical fiber guide, the alignment of the optical fiber can be easily performed, and the workability is improved.

Further, since the positional relationship of the optical fiber to be fused is always determined only by fitting the optical fiber into the guide groove, the length of the fused portion and the contact state for obtaining a desired branching ratio can be reproduced. Thus, an optical fiber fused coupler having good reproducibility can be manufactured without monitoring during fusion. The fixing member provided with the guide groove can be easily manufactured by a molding method.

Further, if the alignment rod and the fixing member are fixed in position after the fusion is completed, it can be used as a part of the package as it is, and it is necessary to carry out a packaging operation in which the optical fiber must be handled as it is bare. Disappears. Therefore, the optical fiber is not damaged during the packaging operation.

[0033]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an optical fiber fused coupler according to an embodiment of the present invention, and FIGS. 2A to 2C show the manufacturing procedure of the embodiment of FIG.

Hereinafter, a method for manufacturing the optical fiber fused type coupler of this embodiment will be described with reference to FIGS. 1 and 2A to 2C.

First, a pair of fixing members 1 are shown in FIGS.
The fixing member 1 is connected by inserting the alignment rod 4 into the alignment hole 3 of the fixing member 1 as shown in FIG.

The optical fiber 5 from which the coating has been removed is arranged in the guide groove 2 provided on the surface of the connected fixing member 1 (see FIG. 2B).

The guide groove 2 has a width slightly larger than the outer diameter of the optical fiber 5, and the optical fiber 5 can be reliably brought into contact in a parallel state by being fitted into the guide groove 2.

The guide groove 2 may be prepared by preparing a metal mold in advance, and may be manufactured by a molding method, or may be machined by an end mill. Moreover, you may machine by a micro end mill.

After the optical fiber 5 has been arranged, both ends of the optical fiber contact portion 6 are fixed to the fixing member 1 with an adhesive or the like. The fixing is performed when the optical fiber 5 is extended.
Is performed so that it does not move but has sufficient fixing strength.

As a guide of the fixing strength, the same strength as the pressing and fixing strength of the optical fiber which has been conventionally performed by the fixing member may be used. However, what should be noted here is that the optical fiber 5 must be fixed in a fully stretched state.
If the optical fiber 5 is not completely stretched, an uneven force is likely to be applied to the optical fiber 5 at the time of fusion, and the optical fiber 5 may be bent or twisted.

After the optical fiber 5 is arranged in the guide groove 2, the optical fiber 5 is heated and melted. The optical fiber contact portion 6 is connected to the optical fiber 5 by a burner (not shown).
Is heated to near the melting point of the optical fiber 5 to melt the optical fiber 5. When the optical fiber contact portion 6 is melted, the fixing member 1 is held,
The fixing member 1 is stretched by being pulled to both sides (see FIG. 2C).

Unlike the conventional stretching method in which the optical fiber itself is held and stretched, all the optical fibers can be stretched with the same force. In addition, the moving direction of the fixing member 1 is determined in advance by the alignment bar 4, and the fixing member 1 can always be stretched straight. Since stable stretching can be performed, very stable optical coupler characteristics can be obtained, and production can be performed with high yield without monitoring the branching ratio.

In the optical fiber fused type coupler manufactured according to the present invention, if the fixing member 1 and the alignment rod 4 are fixed after the optical fiber 5 is fused, the optical fiber 5 becomes a part of the package. It is not necessary to handle the optical fiber 5 as it is bare during processing.

The packaging is sufficient to cover the optical fiber 5 and the outer periphery of the fixing member 1 at a minimum. Therefore, the efficiency of the packaging operation is much higher than in the past. It is possible to solve problems such as an external force acting on the fused portion of the optical fiber 5 to make the characteristics difficult to stabilize, a poor workability due to handling the bare optical fiber, and a breakage of the optical fiber during the packaging operation.

[0046]

As described above, in the method for manufacturing an optical fiber fusion coupler according to the present invention, since an optical fiber is drawn by a fixing member and an alignment rod, an expensive manufacturing apparatus is not required and the drawing can be easily performed. Can do work. In order to obtain such an effect, a configuration in which high precision processing can be easily performed and a fixing member and an alignment bar which are used as a part of the optical fiber fusion coupler are used only.

The extension of the optical fiber is performed by pulling the fixing member to which the optical fiber is fixed to both sides. The fixing member can be moved only linearly by the alignment bar. For this reason, the optical fiber is not bent or twisted at the time of drawing, and stable drawing can be performed.
Further, by providing a guide groove for an optical fiber guide in the fixing member for fixing the optical fiber, the alignment of the optical fiber can be performed easily and reliably, so that the time required for manufacturing can be reduced.

In addition, since the fusion work is performed while protecting the brittle optical fiber by surrounding it with the groove of the substrate, there is an effect that a coupler having good workability, high safety and high reliability can be provided. . Therefore, an optical fiber fused coupler with good reproducibility can be manufactured, and the production yield can be greatly improved.

After the fusion of the optical fibers is completed, the packaging of the fused optical fiber coupler can be constituted only by fixing the alignment rod and the fixing member. For this reason, as in the past,
In particular, there is no need for a packaging operation in which the highly brittle optical fiber fused portion must be handled in an exposed state. For this reason, workability is improved, and there is no defect such as breakage of the optical fiber during packaging.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an apparatus used for manufacturing an optical fiber fused coupler according to an embodiment of the present invention.

FIG. 2 is a front view showing a manufacturing sequence of an optical fiber fusion coupler using the apparatus of FIG.

FIG. 3 is a perspective view showing a manufacturing process of a conventional optical fiber fused coupler.

FIG. 4 is a front view showing a state of an optical fiber fusion splicing part of an optical fiber fusion splicer manufactured by a conventional manufacturing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing member 2 Guide groove 3 Alignment hole 4 Alignment rod 5 Optical fiber 6 Optical fiber contact part 7 Optical fiber fixing part 8 Optical fiber 9 Fixing member 10 Optical fiber contact part 11 Burner

Claims (4)

(57) [Claims] 1. An optical fiber fusion device in which side surfaces of a plurality of optical fibers are arranged in contact with each other, and the vicinity of the center of the contact portion of the optical fibers is heated and melted and stretched to fuse the optical fibers. In the method for manufacturing a shaped coupler, the optical fiber fusion-coupled coupler includes the optical fiber, a pair of fixing members, and a pair of alignment rods, and the aligned side surfaces of the pair of fixing members are aligned with each other. Two through holes each having an inner diameter slightly larger than the rod are provided, and a step of inserting the pair of alignment bars into the through holes of the pair of fixing members, respectively, and another side surface of the pair of fixing members. Fixing the optical fibers brought into contact with each other, and stretching by pulling apart the pair of fixing members while heating and melting the vicinity of the center of the contact portion of the optical fibers. A method for producing an optical fiber fused type coupler, characterized in that: 2. A guide groove having a width slightly larger than an outer diameter of the optical fiber is provided on a surface of the fixing member, and in the fixing step, the optical fiber is fitted and fixed in the guide groove. The method for manufacturing an optical fiber fused coupler according to claim 1, wherein: 3. The method according to claim 1, wherein the fixing member is formed by molding. 4. An optical fiber fusion device in which the side surfaces of a plurality of optical fibers are arranged in contact with each other, and the vicinity of the center of the contact portion of the optical fibers is heated and melted and stretched to fuse the optical fibers. In an apparatus used for manufacturing a shaped coupler, a pair of fixing members and a pair of alignment bars are provided, and opposing side surfaces of the pair of fixing members have a slightly larger inner diameter than the alignment bars. Wherein two through-holes each having the following structure are provided, and a guide groove having a width slightly larger than the outer diameter of the optical fiber is provided on the surface of the fixing member. Equipment used to manufacture couplers.