JPH08122555A - Production of multi-core optical fiber coupler - Google Patents

Abstract

PURPOSE: To provide a multi-core optical fiber coupler where a hermetically sealed structure is adopted to suppress the variance of characteristics against the change of the temperature. CONSTITUTION: Four-core tape-like optical fibers 1 and 2 are used, and glass parts of coated optical fibers 1a and 2a are exposed and are fixed to stretching stages 3a and 3b. Glass parts are clamped and are heated and fusion-spliced by a burner, and stretching stages 3a and 3b are moved by weights 4a and 4b, and the glass parts are stretched to form a coupler part. The incident light from a light source 6 for measurement is given to one end, and outgoing light is monitored by power meters 7a and 7b, and stretching is stopped when a prescribed branch ratio is obtained. The undercoat of an adhesive is put on the optical fiber fixing part or the groove part or a reinforcing material 8, and the optical fiber coupler is set, and the adhesive is applied again, and it is covered with a cover 9 from above, and the adhesive is hardened to protect the optical fiber coupler with the reinforcing material 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multi-fiber optical fiber coupler.

[0002]

2. Description of the Related Art Optical fiber couplers are generally manufactured by a fusion drawing method. The fusion drawing method removes a part of the coating of a plurality of optical fibers to expose the glass part,
After they are heat-fused in a twisted state or arranged in parallel, they are stretched while heating, and when the characteristics such as branching ratio reach a predetermined value, the stretching is stopped to form a joint. Are manufactured. As described above, in the optical fiber coupler having the fusion spliced portion, since the coupler portion is the bare glass fiber, it is necessary to protect this portion from external factors such as external stress.

As a conventional reinforcing structure for an optical fiber coupler, as described in Japanese Patent Laid-Open No. 63-271208, only a stretched portion (small-diameter fusion portion) is suspended, and There is a method of fixing the non-stretched portions (large-diameter fused portions) on both sides to a case (jig) with an adhesive.
Further, as described in JP-A-63-254406, comb-shaped fixing portions having a plurality of grooves are arranged on a substrate so as to oppose each other in the longitudinal direction, and two optical fibers are arranged. A reinforcing structure of a multi-core optical fiber coupler in which a plurality of optical fiber couplers are arranged in a direction orthogonal to the direction and fixed by an adhesive is also known.

In many of the conventional reinforcing structures as described above, the optical coupling portion is not hermetically sealed and the structure does not prevent the infiltration of moisture from the outside, so that the strength deterioration and the transmission at high temperature or in water are required. There is a drawback that it causes fluctuations in loss.

The optical fiber coupler described in Japanese Unexamined Patent Publication No. 5-224062 uses a semi-cylindrical reinforcing material having a groove in the longitudinal direction, and the optical fiber coupler is housed in the groove to form a groove. A reinforcing structure is described in which a reinforcing material is fixed by an adhesive in the vicinity of an end portion, and a central portion of a reinforcing material is sealed with a lid, which is an optical fiber coupler that is hardly affected by environmental changes. However, the optical fiber couplers in the above publications protect each one individually, and cannot protect the multi-fiber optical fiber couplers collectively.

[0006] Regarding a multi-core type optical fiber coupler fixed to a reinforcing material at a time, when a change in characteristics was measured by applying a temperature change, for example, loss fluctuation was found to be abnormally large. As a result of detailed examination, it was found that this was due to the inclusion of air bubbles in the adhesive at the portion where the optical fiber coupler was fixed to the reinforcing material.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and manufactures a multi-fiber optical fiber coupler in which bubbles are not mixed in the adhesive of the fixing portion of the optical fiber coupler. It is intended to provide a method.

[0008]

According to the present invention, after the coating of 2n optical fibers is removed, two fibers are put in parallel each other, and fusion-stretched at one time to form n sets of optical fiber couplers. ,
In the method for manufacturing a multi-core optical fiber coupler fixed to a reinforcing material, when fixing the optical fiber coupler to the reinforcing material,
An adhesive is applied to the optical fiber fixing portion of the reinforcing material in advance, the optical fiber coupler is set on the reinforcing material coated with the adhesive, and then the adhesive is further applied and fixed. .

On the side of the optical fiber, an adhesive may be applied to the fixed portion, and the reinforcing material applied with the adhesive may be set.

[0010]

When the optical fiber coupler is fixed to the reinforcing material, the adhesive is applied to the fixing portion of the reinforcing material in advance, and the optical fiber coupler is set on the reinforcing material coated with the adhesive, so that the fixing portion of the optical fiber coupler is fixed. The area below will be already filled with adhesive. After that, by additionally applying and fixing the adhesive, the added adhesive is well compatible with the already applied adhesive, and it is possible to prevent bubbles from being mixed into the adhesive.

On the optical fiber side as well, if an adhesive agent is applied to the fixed portion and the adhesive agent is applied to the reinforcing material, the inclusion of air bubbles can be further prevented.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram for explaining an embodiment of a method for manufacturing an optical fiber coupler according to the present invention. In the figure, 1 and 2 are tape-shaped optical fibers, 1a and 2a are optical fiber core wires, 3a and 3b are drawing stages, 4a and 4b are weights, 5a and 5b are threads, 6 is a light source for measurement, and 7a and 7b are A power meter, 8 is a reinforcing material, and 9 is a lid.

An optical fiber coupler is manufactured using the two tape-shaped optical fibers 1 and 2. In this example, a four-core tape-shaped optical fiber was used. Opposing the optical fibers of the two tape-shaped optical fibers from above and below,
Since the optical fiber coupler is manufactured by forming the coupler portion by the glass portions of the respective optical fibers facing each other, in this embodiment using two four-core tape-shaped optical fibers,
Two fiber optic couplers are manufactured simultaneously. The optical fiber used for manufacturing is not limited to the four-fiber optical fiber,
A multi-fiber optical fiber other than four fibers can be used. Further, the number of the optical fibers is not limited to the tape-shaped optical fiber, and the required number of single-core optical fibers may be used. The optical fiber cores to be opposed are not limited to be opposed to each other vertically, but may be opposed to each other horizontally. However, when using a multi-core tape-shaped optical fiber, it is usual to make them face each other from above and below.

The drawing stages 3a, 3b have threads 5a, 5
b is attached, and the weights 4a and 4b are attached to the ends of the threads 5a and 5b via the pulleys. A constant tension according to the weight of the weights 4a and 4b is applied to the stretching stages 3a and 3b. The measurement light source 6 causes the measurement light to enter one optical fiber core of one tape-shaped optical fiber 1. The emitted light from the formed coupler unit is measured by the power meters 7a and 7b, and the branching ratio and the excess loss can be measured. The reinforcing material 8 and the lid 9 are set when the stretching is completed. In the groove of the reinforcing material 8,
An adhesive is pre-coated on the fixed portion of the optical fiber in advance, the reinforcing material 8 is raised from below the coupler portion, and the coupler portion is housed in the groove portion of the reinforcing material 8 from the non-stretched portions on both sides of the coupler portion. The adhesive is applied to the covering portion, the adhesive is also applied to the surface of the lid 9 to be adhered, and the optical fiber coupler and the lid are fixed.

The manufacturing method will be described. The tape layer of the tape-shaped optical fibers 1 and 2 is removed over a predetermined length to expose the optical fiber core wires 1a and 2a, and the respective coatings of the optical fiber core wires 1a and 2a are removed over a predetermined length, The glass part is exposed. The coated portions of the two optical fiber core wires 1a and 2a with the glass portions exposed are fixed to the drawing stages 3a and 3b, the glass portions are clamped by a clamper (not shown) to be parallel, and then heated and melted by a burner (not shown). To wear. Then, the clamp of the glass part is removed, and tension is applied to the drawing stages 3a, 3b by the weights 4a, 4b while heating with a burner to draw the drawing stages 3a, 3b.
3b is moved, the glass part is extended, and a coupler part is formed. In the drawing step, one optical fiber core wire 1a
The light beam from the measurement light source 6 is made incident on one end side of the above, and the emitted light is monitored from the other side by the power meters 7a and 7b, and the stretching is stopped when a predetermined branching ratio is obtained. In order to protect the formed coupler portion, the reinforcing material 8 to which an adhesive is applied in advance is set on the optical fiber fixing portion of the groove portion from below the coupler portion, and the coupler portion is housed in the groove portion of the reinforcing material 8. , The adhesive is further applied to the fixed portion, and the same adhesive is applied to the upper surface of the reinforcing member 8. Cover with a lid from above to cure the adhesive and attach the optical fiber coupler to the reinforcing material 8
It can be protected by the lid 9.

FIG. 2 is a plan view of an embodiment of the multi-core type optical fiber coupler of the present invention, and FIG. 3 is a view for explaining an embodiment of a method of fixing the optical fiber coupler to a reinforcing member. A1) and (B1) are cross-sectional views taken along the line AA and BB in the undercoating process.
3A2 and 3B2 are sectional views taken along the line AA and BB in the optical fiber coupler setting step, and FIGS. 3A3 and 3B3 are sectional views taken along the line A- in the overcoating step.
It is the sectional view on the A line and the BB line. In the figure, the same parts as those in FIG. 1b, 2
Reference numeral b is a glass portion, 8a is a groove portion, 8b is an outer convex portion, 8c is an inner convex portion, 10 is an adhesive, and 11 is a coupler portion. In this embodiment, the reinforcing material 8 and the lid 9 are made of crystallized glass. The crystallized glass having a matrix glass content (amorphous content) of 15% or less has a high strength, and the crystallized glass having a matrix glass content of 10 to 12% is more preferable. Of course, quartz or other materials may be used.

In this embodiment, the groove 8a of the reinforcing member 8 is
Two pieces are provided so as to accommodate two pairs of coupler sections 11. Therefore, one inner convex portion 8c is formed in the middle of the two outer convex portions 8b. Outside convex portion 8
The width of b and the width of the inner convex portion 8c may be the same, but it is desirable that the width of the outer convex portion 8b is large from the viewpoint of preventing the intrusion of moisture. This is because, when the lid 9 is bonded to the reinforcing material 8, if the width of the outer convex portion 8b is large, the bonding area to the outside becomes large. The width of the inner convex portion 8c is preferably determined in consideration of the width of the groove portion 8a and the distance between the optical fiber couplers.

The groove portion of the reinforcing member 8 is not limited to the accommodation of two sets of optical fiber couplers. When accommodating four optical fiber couplers, the number of grooves of the reinforcing member 8 may be one, and all the couplers may be accommodated in one groove, or one coupler may be accommodated in each groove. It may be provided with four grooves so as to be accommodated.

The lid 9 for the reinforcing member 8 may be made of transparent crystallized glass. If the lid 9 is transparent,
It is possible to shorten the curing time by using an energy curable adhesive, for example, an ultraviolet curable adhesive. In this case, the adhesive for fixing the coupler portion and the adhesive for fixing the lid can be simultaneously cured.

The coupler portion 11 is housed in the groove portion of the reinforcing member 8, and the glass portions 1b and 2b on both sides thereof are covered with the covering portions 1a and 2a.
It is fixed by the adhesive 10 over a. As described above, the energy curable adhesive can be used as the adhesive 10, but a thermosetting adhesive or a reactive adhesive using a polymerizing agent may be used. A method of fixing the optical fiber coupler will be described. As shown in FIGS. 3A1 and 3B1, the adhesive 10 is undercoated on the bottom of the groove 8a. You may apply thinly also to the side wall of the groove part 8a. Then, as shown in FIG.
2) and (B2), the optical fiber coupler is placed on the portion of the groove portion 8a where the adhesive is undercoated. The fixed portion of the optical fiber coupler is from the non-stretched portion of the glass portion 1b to the covering portion 1a, but an adhesive may be pre-coated on this portion as well.

As shown in FIGS. 3A3 and 3B3, the adhesive 10 is filled in the groove 8a. Since the adhesive is undercoated on the bottom of the groove, bubbles can be prevented from entering. An adhesive is also applied to a lid (not shown), which is attached on the reinforcing material 8 and cured together with the adhesive of the optical fiber fixing portion.

A specific example of the above embodiment will be described. 0.3% difference in refractive index between core and clad, core diameter 8μ
m, a 1.3 μm band single mode optical fiber having a clad diameter of 125 μm, and four cores of an optical fiber having two layers of protective films coated with a tape layer were used as two four-core tape-shaped optical fibers. Remove a part of the tape layer, further remove a part of the protective film, overlap the exposed glass part in parallel,
At this portion, the glass portions of the corresponding cores of both tape-shaped optical fibers were fusion-bonded and drawn to prepare a 4-fiber optical fiber tape coupler.

This optical fiber coupler was set in advance on a reinforcing material having a groove portion in which the non-stretched portion of each optical fiber fits. The reinforcing material is made of white glass-ceramic and has a depth of about 0.1 mm from the both ends of the groove to about 1 cm.
The UV-curable adhesive was pre-coated with a thickness of 1.
After setting the optical fiber coupler, further apply a UV curable adhesive to this undercoated area, and attach a transparent glass-ceramic lid with a thin coating of UV curable adhesive on the adhesive surface to attach the entire reinforcing material. The adhesive was cured by irradiating it with ultraviolet rays so that the ultraviolet rays for curing would be applied to the four-core tape coupler.

A comparative example will be described. Create a multi-fiber optical fiber coupler similar to the above, set it in a white glass-ceramic reinforcement material, apply UV-curable adhesive to the non-stretched parts of each optical fiber in the groove parts at both ends of the case, and then clear A glass-ceramic lid was attached, and the entire reinforcing material was cured and fixed by irradiating it with ultraviolet rays for curing. At this time, the reinforcing material was used in a state where the ultraviolet curable adhesive was not applied in advance.

Regarding the examples and the comparative examples, after production-
A thermal shock test at 40 ° C to + 85 ° C was performed. In addition, the sample to be tested is cut at the portion containing the adhesive,
Upon observation, no abnormality was found in the groove,
In the comparative example, the adhesive did not fully reach the bottom of the groove, and bubbles 12 were confirmed as shown in FIG. 4 (B).
On the other hand, in the example, as shown in FIG. 4 (A), the adhesive 10 was completely filled, and no inclusion of bubbles was observed. In addition, FIG. 4 (A) and (B) are BB of FIG.
It is sectional drawing in a line. Even in the loss measurement after the test,
As shown in, a large loss variation was confirmed in the comparative example. On the other hand, in the example, the variation was extremely small even in the loss measurement.

[0026]

As is apparent from the above description, according to the present invention, there is an effect that it is possible to provide a multi-fiber type optical fiber coupler having a small characteristic variation with respect to temperature variation.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram for explaining a manufacturing method of an embodiment of an optical fiber coupler of the present invention.

FIG. 2 is a plan view of an embodiment of a multi-fiber optical fiber coupler of the present invention.

FIG. 3 is an explanatory view of an embodiment of a method for fixing a multi-fiber optical fiber coupler of the present invention to a reinforcing material.

FIG. 4 is an explanatory diagram of observation results obtained by experiments.

FIG. 5 is an explanatory diagram of measurement results by experiments.

[Explanation of symbols]

1, 2 ... Tape-shaped optical fiber, 1a, 2a ... Optical fiber core wire, 2a, 2b ... Glass part, 3a, 3b ... Stretching stage, 4a, 4b ... Weight, 5a, 5b ... Thread, 6 ... Measuring light source, 7a, 7b ... Power meter, 8 ... Reinforcing material, 8a ... Groove, 8b ... Outer convex, 8c ... Inner convex, 9 ... Lid, 10 ...
Adhesive, 11 ... Coupler part.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location G02B 6/28 W (72) Inventor Yoichi Ishiguro 1 Tayacho, Sakae-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industries Inside Yokohama Works, Ltd. (72) Inventor Moriya Tomomi 1 Taya-cho, Sakae-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industries, Ltd. Inside Yokohama Works

Claims (1)

[Claims] 1. The coating of 2n optical fibers is removed, and 2
In a method of manufacturing a multi-core optical fiber coupler, which is arranged in parallel one by one, and fused and stretched together to form n sets of optical fiber couplers, which are then fixed to a reinforcing material. When fixing, an adhesive is applied to the optical fiber fixing portion of the reinforcing material in advance, the optical fiber coupler is set on the reinforcing material coated with the adhesive, and then the adhesive is applied to fix the optical fiber coupler. Method for manufacturing multi-core optical fiber coupler.