JPH01239509A - Production of optical fiber coupler - Google Patents

Abstract

PURPOSE:To improve the uniformity of coupling ratios by stretching 1st and 2nd optical fiber groups while simultaneously subjecting a part in the longitudinal direction of said optical fiber groups to heating to the extent of softening the optical fiber groups after a tight contact stage, then welding the parts which are not reduced in fiber diameter by the 1st stretching and stretching the welded part. CONSTITUTION:The optical fibers 1204a-e of the 2nd optical fiber group are brought into nearly tight contact with each other with the respective optical fibers 1203a-e of the 1st optical fiber group and while the optical fiber groups 1203a-e, 1204a-e of the 1st and 2nd optical fiber groups are partly heated in this state, the optical fiber groups which are held in nearly tight contact with each other are subjected to the 1st stretching. The pats which are not reduced in the diameter by the 1st stretching in the longitudinal part of the 1st and 2nd optical fiber groups are then heated to weld the optical fibers of the 1st and 2nd optical fiber groups to each other to form the welded part 1207. The welded part 1207 is stretched. The fluctuation in the coupling ratios is thereby decreased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of manufacturing an optical fiber coupler, and more specifically to a method of manufacturing a plurality of optical fiber couplers having uniform characteristics at the same time. be.

(Prior Art) With the recent progress in optical signal transmission technology, many types of optical systems such as optical communication systems or optical sensor systems have been proposed and put into practical use.General issues in signal transmission technology Therefore, approaches to high-density and speed signal transmission, stabilization of characteristics of various elements, and cost reduction are always issues in optical systems.

By the way, an optical coupler that has the function of branching/merging light is an essential optical element in constructing an optical system.Currently, fused optical fiber couplers are used because of their low loss and connection with other optical fibers. Due to its excellent performance, it is being considered for introduction into the system. However, the conventional manufacturing method for optical fiber couplers involves manufacturing them individually, which poses problems in mass production and increases the cost accordingly.

Therefore, in order to improve mass production, a method of fabricating multiple optical fiber couplers at the same time is disclosed in Japanese Patent Application Nos. 62-38740 and 62-38741 related to the applicant's earlier application.
No. 62-278173.

In this method, a first optical fiber group is formed by arranging multiple rows of optical fibers parallel to each other on the same plane, and the first optical fiber group is arranged on a predetermined plane parallel to the arrangement plane of the first optical fiber group. A second optical fiber group is formed parallel to the optical fiber strands of the first optical fiber group and arranged at the same pitch, and each of the first and second optical fiber groups is The exposed corresponding optical fiber strands are kept in close contact with each other and heated all at once, the corresponding optical fiber strands are fused together, and then stretched to form multiple optical fiber couplers at the same time. Here, the term "optical fiber strand" refers to an optical fiber in which the coating including the primary coat (primary coating) has been removed so that the glass surface is exposed.

Incidentally, the above-mentioned Hikari application discloses an apparatus shown in FIGS. 5(a) and 5(b) as an example of a manufacturing apparatus for carrying out such a manufacturing method.

In addition, Kowara's diagram shows an apparatus for manufacturing an element equipped with five optical fiber couplers using two five-core tape-shaped multicore optical fibers, and Fig. 5 (a) and (
b) shows a state in which a five-core tape-shaped multicore optical fiber is attached to the device.

This device mainly consists of a pair of stretching tables llA and 11B.
and heating torches 128 and 1211 as heating means.
The stretching tables 11A and 11B consist of fixing means 111A and 111B for fixing a tape-shaped multicore optical fiber including its outer coating, which will be described later, and a single optical fiber from which the coating has been removed horizontally. a pair of bin groups 112A, 113A, and 1128, 113B for positioning the optical fibers in the vertical direction, and means 1 for vertically positioning the optical fibers by moving them in the vertical direction, that is, for vertically positioning the optical fibers in close contact with each other in the vertical direction. eyes A and 114B, respectively.

Although driving means for the stretching tables 118 and 118 are not shown, the pair of stretching tables 11^ and IIB are moved away from each other with equal driving force along the guide members +208 and 120B, respectively. It is configured to allow 8 movements. Furthermore, rolls 13A, 138, 13 (: and 13
As will be described later, tension is applied to the tape-shaped optical fiber core wire by a pulling means (not shown) disposed further outside these rolls.

In addition, the above-mentioned bins glJ2A, 113A and 112B
and 1138, piano wires with an outer diameter of 123 μm and a length of 2 mm were used and were fixed perpendicularly to each surface of the stretching tables 11A and IIB, and the arrangement interval was 250 μm. Also,
Fixing means 111^ and IIIB and adhesion means 1
14A and 114B are configured to press one plate against a plurality of bare optical fibers via elastic means to fix or bring these bare optical fibers into close contact with each surface of drawing tables 11A and 11B. This is a consideration to ensure that a uniform load is applied to the plurality of optical fiber strands, as will be described later.

Now, here, examples of the tape-shaped multicore optical fiber include a 138-meter IF single-mode optical fiber with a core diameter of 6.5 μm, a cladding outer diameter of 125 μm, and a cutoff wavelength of 1.1 μm, a urethane or acrylic UV-curable optical fiber Coated optical fibers coated with a mold resin to have an outer diameter of 250 μm are arranged in five parallel planes on a plane, and are further integrated with urethane or acrylic ultraviolet curable resin to a thickness of about 75 μm.

Next, using the apparatus shown in FIGS. 5(a) and 5(b), five sets of optical fiber couplers are produced from the above-mentioned tape-shaped multicore optical fiber by the method previously proposed by the applicant. The operation for producing an optical member equipped with the following will be described.

First, each has five optical fiber strands 21a.

21b, 21c, 21d, 21e and 22a, 22b
, 22c, 22d, and 22e (of which only 21a and 22δ are shown as side surfaces in FIG. 5(a), and only 21e and 22e are shown as side surfaces in FIG. 5(b)). For the five-core tape-shaped optical fibers 21 and i2, the X shown in FIGS. 5(a) and (b)
Over a length corresponding to between -x, each coating layer is removed with polyethylene glycol and sulfuric acid.

Next, first, the tape-shaped optical fiber 22 is placed in bins 1128 and 1138 and 112B and 1 so that the optical fiber strands 22a to 22e are located at equal intervals.
138. Next, the tape-shaped optical fiber 21 is stacked on the tape-shaped optical fiber 22, and the bins 112A, 1138, and 112
B and 113[1. Note that due to the above-mentioned arrangement of the bins, the optical fibers are separated from each other by approximately 1
The width of the tape-shaped optical fiber as a whole is about 1.2 mm.

Subsequently, the tape-shaped optical fibers 21 and 22 are fixed together by the fixing means 111A on the drawn gold-platinum A side, and the tape-shaped optical fibers 21 and 22 are fixed together via the roll groups 13A, 13B, 13C, and 13D. Approximately 50 g of tension is applied to the stretching table 11 while maintaining this state.
The tape-shaped optical fiber 2 is fixed by the fixing means 111B on the B side.
1 and 22 are fixed. That is, the tape-shaped optical fiber is fixed between the stretching table 11Δ and IIB while maintaining a tension of about 50 g, and during these operations,
The stretching tables 11^ and 11B are fixed so as not to move.

Next, each optical fiber strand of the tape-shaped optical fiber 21 is
The adhering means 114A is arranged so that each of the tape-shaped optical fibers 22 is brought into close contact with the corresponding optical fiber strands, that is, each of the optical fiber strands corresponding to each other in the vertical direction are brought into close contact with each other.
and 114B are pushed down,
Closely attached to each other, 21a-22a.

21b-22b, 21cm22c, 21d-22d, 2
Create a set of 1e-22e (Fig. 6 (a) and (b)
reference). In addition, in FIG. 4(a), a part of the adhesion means 114A is cut away to show the state of the optical fiber strand.

At a substantially intermediate position between the drawing tables 118 and 1111, where the optical fibers are kept in close contact with each other after the arrangement has been completed, a pair of heating torches 12A and 12B arranged above and below are used to Optical fiber wire set 21a
-22a, 21b-22b, 21cm22c, 21d-
22d.

21e-22e are heated and fused together (see FIGS. 6(c) and 6(d)).

Once the fusion of each optical fiber is confirmed in this way,
While reducing the respective outputs of the heating tools 128 and 12B and maintaining a state in which the optical fiber is softened and can be drawn, both the drawing tables 11A and 11B are moved away from each other. By moving at the same speed, five sets of optical fiber couplers as shown in FIGS. 6(e) and 6(f) are fabricated.

In addition, in this operation, the output light of the semiconductor laser is injected from one end of the optical fiber strand 21a, and the other end of the optical fiber strand 21a and the optical fiber element paired with this optical fiber strand 21a are injected. A light receiving element 24 is placed at the end of the wire 22a.
and 25, respectively, and the characteristics of the optical fiber coupler formed along with the drawing operation are monitored.

That is, at the beginning of the operation, there is no output in the light receiving element 25, and only when the extension length reaches 5 mm to 30 mm, the branching operation occurs and an output appears in the light receiving element 25. Therefore, the output light intensity of each of the light receiving elements 24 and 25 is monitored, and when a desired value is obtained, the stretching and heating are stopped, thereby completing an optical fiber coupler with desired characteristics.

In addition, in FIGS. 6(c) and (d), 35 is a fused part obtained by heating with a torch, and in FIGS. 6(e) and (f), 36 is a fused part formed by stretching after fusion. This is the fused and stretched part.

[Problem to be solved by the invention]

By the way, in order to obtain a uniform bonding ratio, it is necessary to make the tensions applied to each fiber end substantially uniform before the fusion process.

However, in the conventional method described above, the tension applied to each optical fiber strand from outside the drawing table is adjusted before the corresponding optical fiber strands are brought into close contact with each other.

For this reason, it is not guaranteed whether the tension applied to each optical fiber strand after the adhesion process is uniform. As a result, for optical fiber couplers manufactured using conventional methods, the yield rate at which variations in coupling ratio can be suppressed to within ±2% is 2.
It was about 0%, and the yield was low.

An object of the present invention is to manufacture an optical fiber coupler that can increase the uniformity of the tension applied to each fiber strand before the fusion process and suppress variations in the coupling ratio of the resulting optical fiber coupler. The purpose is to provide a method.

[Means for Solving the Problems] In order to achieve such an object, the present invention arranges a plurality of rows of optical fibers so as to be parallel to each other on the same plane to form a first optical fiber group. Optical fiber strands are formed and arranged on a predetermined plane parallel to the arrangement plane of the first optical fiber group, parallel to and at the same pitch as the respective optical fiber strands of the first optical fiber group. are arranged in a plurality of rows to form a second optical fiber group, and the optical fiber strands of the second optical fiber group are brought into close contact with each other in correspondence with each optical fiber strand of the first optical fiber group. In this state, some portions in the length direction of the optical fiber groups of the first and second optical fiber groups are heated to an extent that they are softened all at once, and the optical fiber groups are brought into close contact with each other. The first stretching is performed by applying tension, and the portions in the length direction of the first and second optical fiber groups that have not been reduced in diameter by the first stretching are heated, and the first optical fiber group is A fused optical fiber strand and an optical fiber strand of a second optical fiber group corresponding to the optical fiber strand are fused together to form a fused portion, and the fused portion is softened to the extent that the fused portion is softened. The method is characterized in that a plurality of optical fiber couplers are formed at the same time by applying tension to the fused portion and performing the second stretching while heating the fused portion at once.

In another aspect of the present invention, a plurality of rows of optical fibers are arranged parallel to each other on the same plane, and a portion of the arrayed optical fibers is arranged in a part of the longitudinal direction of the group of arranged optical fibers. A first optical fiber group is formed by applying tension to and stretching the optical fiber strands while heating to an extent to soften them, and on a predetermined plane parallel to the arrangement plane of the first optical fiber group, A second optical fiber group is formed by arranging a plurality of rows of optical fibers so as to be aligned parallel to each optical fiber strand of the first optical fiber group and at the same pitch, and the first optical fiber The optical fiber strands of the second optical fiber group are brought into substantially close contact with each other corresponding to each optical fiber strand of the group, and the first of the longitudinal portions of the first and second optical fiber groups that are brought into close contact with each other is The part of the optical fiber group corresponding to the part that is not reduced in diameter is heated, and the optical fiber element of the first optical fiber group and the optical fiber element of the second optical fiber group corresponding to the optical fiber element are heated. The wires are fused to each other to form a fused portion, and the fused portion is heated all at once to the extent that the fused portion is softened, while tension is applied to the fused portion to perform a second stretching. , is characterized in that a plurality of optical fiber couplers are formed simultaneously.

[Effect]

In the conventional manufacturing method of manufacturing multiple optical fiber couplers at the same time, the corresponding optical fibers of the first optical fiber group and the second optical fiber group are brought into close contact with each other, and then fused and stretched. However, in the present invention, after the adhesion process, optical fiber groups are simultaneously manufactured in a part of the length direction of the first and second optical fiber groups. While heating to an extent that softens the optical fiber group, tension is applied to the group of optical fibers to perform a first drawing, and then the portions that have not been reduced in diameter by the first drawing are fused,
The fused part is produced by stretching.

According to the present invention, it is possible to equalize the tension applied to each optical fiber by the first drawing before the fusion process, and it is possible to improve the uniformity of the coupling ratio of a plurality of optical fiber couplers that are simultaneously produced. The yield can be increased.

〔Example〕

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

Figures 1 (a) to (h) schematically show the manufacturing process according to an embodiment of the present invention. Note that this example uses five-core tape-shaped multicore optical fibers 1201 and 1202, and FIGS.
) is a top view at each step, (b), (d), (f
) and (h) are side views at each step.

First, as shown in FIGS. 1(a) and 1(b), the protective coating of the tape-shaped multicore optical fibers 1201 and 1202 is removed over a predetermined section at the same longitudinal position, and the exposed optical fiber element is removed. Line groups 12Q3a-e and 1204
A to e are arranged parallel to each other on the same plane to form first and second optical fiber groups, corresponding to 1203a and 1204a.

1203b and 1204b, 1203c and 1204
c, 1203d and 1204d %1203e and 12
04e were arranged so as to overlap each other and brought into close contact with each other.

Subsequently, the optical fiber groups 1203a to 1204a to 1204a to 1204a, which have been brought into close contact with each other, are heated to such an extent that some portions in the longitudinal direction of the fibers are softened, and tension is applied to draw them.
) and (d), first stretched portions 1205 and 1206 were formed. Through this process, even if it is shown in Figure 1 (
In the states of a) and (b), the optical fiber group 12
Even if there is variation in the tension applied to 03aNe and 1204a to 1204e, it is alleviated by stretching and the variation in tension becomes extremely small in the states shown in FIGS. 1(c) and 1(d).

Next, as shown in FIGS. 1(e) and 1(f), the optical fiber strands at different positions in the length direction from the first stretched parts 1205 and 1206 are heated and fused to form a fused part 1207. Form.

Subsequently, the fused portion 1207 is heated and stretched to form a fused stretched portion 1208 as shown in FIGS. 1(g) and (h), and when the desired characteristics are obtained, the stretching is stopped and five We were able to form an optical fiber coupler.

Incidentally, in order to carry out such a step, in this example, the manufacturing apparatus shown in FIGS. 5(a) and 5(b) described above was used.

In this example, the tape-shaped multi-core optical fiber has a core diameter of 65 μm and a crut outer diameter of 12 μm.
Five single-mode optical fibers for the 1.3 μm band with a cutoff wavelength of 1.1 μm and an outer diameter of 250 μm coated with urethane or acrylic ultraviolet curable resin are arranged in rows on a flat surface. and approximately 75μ
A material made of urethane or acrylic ultraviolet curable resin with a thickness of m was used.

The operation of producing an optical member equipped with five sets of optical fiber couplers from this tape-shaped multicore optical fiber using the apparatus shown in FIGS. 5(a) and 5(b) will be described below.

First, each of the five optical fiber strands 1203a to 1
A pair of 5-core tape-shaped optical fibers 1201 and 120 formed from 2Q3e and 1204a-1204e
2, X-x shown in FIGS. 5(a) and (bl)
Over a corresponding length in between, each coating layer was removed with polyethylene glycol and sulfuric acid.

Next, first, the tape-shaped optical fiber 1202 was positioned using the bins 112A and 113A and +11211 and 113[1 so that the optical fiber strands 1204a to 1204e were positioned at equal intervals. Next, the tape-shaped optical fiber 1201 is stacked on the tape-shaped optical fiber 1202, and the optical fiber strand 1203a N
The bins 112A and 113A and 112B and 113B were also positioned so that the bins 1203e were equally spaced from each other. Furthermore, depending on the arrangement of the bins mentioned above,
The optical fiber strands are separated from each other by approximately 125 μm, and the width of the entire tape-shaped optical fiber is approximately 1.2+++ m.

Subsequently, on the stretching table 118 side, the tape-shaped optical fibers 1201 and 1202 are collectively fixed by the fixing means illΔ, and the roll groups 13A, 138, 13G, 1
Through 3D, tape-shaped optical fibers 1201 and 12
02 was applied with a tension of about 50 g, and further, while maintaining this state, the tape-shaped optical fibers 21 and 22 were fixed by the fixing means 111B on the drawing table 11B side. That is,
The tape-shaped optical fiber is fixed with a tension of about 508 between the drawing table 11^ and IIB, and during these operations, the drawing table 11^ and IIB are fixed so as not to hyper-move. has been done.

Next, each optical fiber strand of the tape-shaped optical fiber 1201 is brought into close contact with the corresponding optical fiber strand of the tape-shaped optical fiber 1202, that is, the optical fiber strands corresponding to each other in the vertical direction are brought into close contact with each other. , by pushing down the contact means 114A and 1148, the optical fibers are brought into close contact with each other 1203a-1.
204a, 1203b-1204b, 1203cm12
04c.

I made pairs 1203d-1204d and 1203e-1204e.

When the arrangement is completed and the optical fibers are in close contact with each other, the heating torch 12A is heated all at once to the extent that a part of the optical fibers in the length direction is softened.

12B, and tension was applied using stretching tables 11A and 11[1 to perform the first stretching. Even if there is a difference in the tension applied to each optical fiber strand, the tension is released by the first drawing, and the tension applied to each optical fiber after the first drawing is , 11B, the tension applied to the optical fiber group is equalized to a value obtained by dividing the tension by the number of optical fibers.

Subsequently, a pair of heating torches 1 are placed one above the other at a position in the length direction where the diameter has not been reduced by the first stretching.
A set of optical fibers 1203a by 2A and 12B
-1204a, 1203b-1204b, 1203cm
1204c.

1203d-1204d and 1203e-1204e were heated and fused together.

When the fusion of each optical fiber is confirmed in this way, the outputs of the heating torches 128 and 12B are reduced, and the drawing table 118 is moved while maintaining the state in which the optical fibers are softened and can be drawn. and IIB are moved away from each other at approximately equal speeds, thus 5
By simultaneously manipulating two sets of optical fiber strands,
A set of optical fiber couplers was fabricated.

Note that during this operation, the output light of the semiconductor laser is injected from one end of the optical fiber strand 1203a, while the other end of this optical fiber strand 1203a and the optical fiber strand that is paired with this optical fiber strand 1203a are injected. Light-receiving elements 24 and 25 were placed at the ends of 1204a, respectively, and the characteristics of the optical fiber coupler formed during the stretching operation were monitored.

That is, at the beginning of the operation, the light receiving element 25 has no output, and only when the extension reaches 5 mm to 30 mm does the branching operation occur, and an output appears on the light receiving element 25. Therefore, by monitoring the output light intensity of each of the light receiving elements 24 and 25 and stopping the stretching and heating when the desired value is obtained,
An optical fiber coupler with desired characteristics is completed.

In this example, the coupling ratio was manufactured to be 50% at a wavelength of 1.3 μm, and as a result, the variation in the coupling ratio was within ±0.6%. When the same fabrication was performed multiple times and the characteristics were evaluated, the yield with the variation in bonding ratio within ±2% was over 90%, which was the conventional yield (20%).
%). Furthermore, by employing the manufacturing method of the present invention, it was found that the tension adjustment before the adhesion step was required to be more rough than in the past, and this was also effective in simplifying the manufacturing process of the present invention.

Embodiment 2 In a system that uses two or more wavelengths, such as multi-wavelength optical transmission, an optical fiber coupler with a small wavelength dependence of the coupling ratio is required. An optical fiber coupler having such characteristics can be obtained by fusion-drawing an optical fiber that has been previously drawn to have a smaller diameter and an undrawn optical fiber.

(References: D, B, Mortimore, Ele
ctronics Letters, vol. 21.degree. pp. 742-743.1985) This example shows an example in which a plurality of optical fiber couplers whose coupling ratios are less dependent on wavelength are manufactured simultaneously with a high yield.

The difference between this example and Example 1 is that the first
The difference is in the method of forming the optical fiber groups. In the manufacturing process of Example 1 shown in FIG. 1, (a),
This example differs from Example 1 in the steps up to (b), and the following steps (c) to (h) are similar. That is, in FIG. 2 showing a part of the process of this example,
(a'-1) ~ (a-43 and (b'-1) ~ (b
'-4) is Fig. 1 for Example 1, (a) and (b)
) corresponds to the steps shown in . In addition, Fig. 2 (a
'-1) to (a'-4) are on the top surface in each step, (b'
-1) to (b'-4) are side views thereof.

First, as shown in FIGS. 2(a'-1) and (b'-1), the protective coating of the tape-shaped multicore optical fiber 2202 is removed over a predetermined section at the same longitudinal position, and the exposed light is removed. Fiber wire groups 2204a to 2204e were arranged parallel to each other on the same plane.

Next, as shown in FIGS. 2(a'-2) and (b-2), tension is applied to the portions other than the longitudinal positions that are planned to be fused in a later step while being heated to an extent to soften them. It was stretched to form a stretched portion 221O outside the area to be fused.

Next, as shown in FIGS. 2(a'-3) and (b'-3), the portions in the longitudinal direction that are to be fused are heated to a softening extent while applying tension, stretched, and fused. A stretched portion 221 (to be arrived at) was formed, and the first optical fiber strand group was formed as a whole.

Next, as shown in FIGS. 2(a-4) and (b'-4), the protective coating of the tape-shaped multicore optical fiber 2201 is removed over a predetermined section at the same longitudinal position, and the exposed light is removed. The fiber strands 2203a-6 are arranged on a predetermined plane parallel to the arrangement plane of the first optical fiber strand group, parallel to and at the same pitch as the optical fiber strands of the first optical fiber strand group. A second optical fiber strand group was formed, and corresponding optical fiber strands of the first optical fiber strand group and the second optical fiber strand group were brought into close contact with each other. After that, steps (c) and (d), steps (e) and (f) in FIG. 1,
Steps (g) and (h) were carried out to produce a plurality of optical fiber couplers as shown in (co) and (d) of FIG. Here, 2205 and 2206 are first drawn parts, and 2208 is a fused drawn part. Comparing with (g) and (h) of FIG.
The diameter is smaller than that of 5, and the fused and stretched portion 2208
They have the same shape except that they are asymmetrical.

In this example, FIG. 2 (a'-2) and (b'-
In the step 2), each optical fiber strand 2204a to 2204
This is to equalize the tension applied to e.
Uniform tension can be achieved by forming the stretched portions 221O in areas other than those planned for fusion. As a result, in the steps shown in FIGS. 2(a'-3) and (b'-3), when forming the stretched portion 2211 to be fused, each optical fiber strand is uniformly stretched and has a uniform shape. can be formed.

That is, if the shape of the stretched portion 2211 to be fused is non-uniform, the uniformity of the coupling ratio of the manufactured optical fiber coupler will be affected. This is extremely necessary in order to improve the uniformity of the coupling ratio of the optical fiber coupler to be manufactured.

Note that in the steps of FIG. 2 (a'-1) and (b''-1), if the tension applied to the optical fiber groups 2204 a to e can be made sufficiently uniform (for example, when single-core optical fibers are arranged ), Figure 2 (a'-2) and (
It is also possible to omit step b''-2).

FIG. 3 shows the wavelength characteristics of the coupling ratio of one of the five-core optical fiber couplers manufactured using this example. As shown in this figure, the coupling ratio could be kept within the range of 0.47 to 0.55 at wavelengths of 1.3 μm to 1.55 μm.

Comparing FIG. 4 and FIG. 3, which show the wavelength characteristics of the coupling ratio of the optical fiber coupler manufactured in Example 1, it can be seen that an optical fiber coupler in which the wavelength dependence of the coupling ratio is small can be manufactured according to this example.

Incidentally, the variation in the coupling ratio of the five-core optical fiber coupler produced in this example was within ±1% at each wavelength.

When the same manufacturing method was carried out multiple times and its characteristics were measured, the present invention was found to be effective as a high yield of 90% or more was achieved with variations in the bonding ratio within ±2%. I understand that.

In addition, in Examples 1 and 2 above, an example was shown in which a tape-shaped multicore optical fiber was used, but it is also possible to arrange a plurality of single-core optical fibers in multiple rows as a group of optical fibers, Of course, the present invention can also be applied to a case where a plurality of single-core optical fibers are appropriately folded back and arranged in a plurality of rows.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to improve the uniformity of the coupling ratio when manufacturing a plurality of optical fiber couplers at the same time, which has the advantage of improving the manufacturing yield and achieving high productivity. be.

[Brief explanation of the drawing]

FIGS. 1(a), (c), (e), and (g) are top views showing an example of the manufacturing process of the present invention, and FIG. 1(b) is a top view showing an example of the manufacturing process of the present invention.
, (d), (f), and (h) are side views corresponding to FIG. 1 (a), (c), (e), and (g), respectively, and FIG. 2 (a'-1), ( a'-2), (a'-3)
, (a-4), (c') is a top view showing an example of the manufacturing process according to Example 2 of the present invention, FIG. 2 (b"-1),
(b'-2), (b'-3), (b'-4). (do) are respectively shown in Figure 2 (a'-1) and (a'-
2), (a'-3>. (a'-4), side view corresponding to (c'), FIG. 3 is a diagram showing the coupling ratio wavelength dependence of the optical fiber coupler produced in Example 2, FIG. 4 is a diagram showing the coupling ratio wavelength dependence of the optical fiber coupler manufactured in Example 1. FIGS. 5(a) and (b) are plane views showing the configuration of an example of the optical fiber coupler manufacturing apparatus. 6(a), (c), and (e) are top views showing the conventional manufacturing process, and FIG. 6(b), (d), and (f) are top views showing the conventional manufacturing process.
) are shown in Figures 6(a), (c), and (e), respectively.
FIG. 11Δ, IIB... Stretching table, 12A, 12B... Heating torch, 13A, 1:In, 13G, 13D... Roll, 21
．． 22,12014202,2201.2202...
Tape-shaped multicore optical fiber, 2+a to 21e, 22a to 22e, 1203a,
~1203ej204a, ~1204e, 2203a
~2203e, 2204a ~2204e - Optical fiber strand, 1205.1206... First stretching part, 1207.35
... Fusion part, 1208.36.2208 ... Fusion extension part, 23.2
4... Light receiving element, 1118, 111 [J... Core wire fixing device, 1128,
112B, 113A, 113B...Hin, 114A
, 114B... @ attachment means, 1208, 120B... guide member, 2205.2206... first extension part, 2208...
Stretched part for fusion, 2210, Stretched part outside the planned fused part, 2211...
Stretched area to be fused. Patent applicant Nippon Telegraph and Telephone Corporation

Claims (1)

[Scope of Claims] 1) (a) A first optical fiber group is formed by arranging a plurality of optical fiber strands in parallel to each other on the same plane, (b) the first optical fiber A plurality of rows of optical fibers are arranged on a predetermined plane parallel to the group arrangement plane so as to be aligned parallel to each optical fiber strand of the first optical fiber group and at the same pitch. (c) bringing the optical fiber strands of the second optical fiber group into substantially close contact with each other in correspondence with each optical fiber strand of the first optical fiber group, and in that state; A part of the optical fiber strands of the first and second optical fiber groups in the longitudinal direction are heated to an extent that they are softened all at once, and the optical fiber strands are brought into close contact with each other. performing a first drawing by applying tension; (d) heating a portion in the length direction of the first and second optical fiber groups that has not been reduced in diameter by the first drawing; fusing together the optical fiber strands of the first optical fiber group and the optical fiber strands of the second optical fiber group corresponding to the optical fiber strands to form a fused portion; (e) A plurality of optical fiber couplers are simultaneously formed by heating the fused portion at once to an extent that the fused portion is softened and applying tension to the fused portion to perform a second stretching. A method for manufacturing an optical fiber coupler. 2) (a) Arrange multiple rows of optical fibers so that they are parallel to each other on the same plane, and the part is arranged in a part of the length direction of the arranged optical fibers group. applying tension to and stretching the optical fiber group while heating to an extent to soften it to form a first optical fiber group; (b) a predetermined line parallel to the arrangement plane of the first optical fiber group; A second optical fiber group is formed by arranging a plurality of rows of optical fibers on a plane so that they are aligned parallel to and at the same pitch as the portions of the optical fibers of the first optical fiber group; (c) the optical fiber strands of the second optical fiber group are brought into substantially close contact with each other corresponding to each of the optical fiber strands of the first optical fiber group; (d) the first and second optical fibers are brought into close contact with each other; Among the lengthwise portions of the optical fiber group, a portion corresponding to the portion of the first optical fiber group that is not reduced in diameter is heated, and the optical fiber strands of the first optical fiber group and the (e) fusing the optical fiber strands with the optical fiber strands of the second optical fiber group corresponding to each other to form a fused portion; (e) bonding the fused portion to such an extent that the fused portion softens; A method for producing an optical fiber coupler, characterized in that a plurality of optical fiber couplers are simultaneously formed by performing a second stretching by applying tension to the fused portion while heating all at once.