JP2800601B2 - Manufacturing method of optical fiber coupler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing an optical fiber coupler, and more particularly to a method for simultaneously manufacturing a plurality of optical fiber couplers having the same characteristics.

[0002]

2. Description of the Related Art An optical fiber coupler is manufactured by removing a coating of a plurality of optical fibers, heating them in a state in which they are in close contact with each other, fusing them together, and further stretching them by heating. Glass optical fiber has an outer diameter of 125μ
Since the glass body is a very thin glass body of about m, precise precision is required for manufacturing an optical fiber coupler. For this reason, the productivity of the optical fiber coupler was low, and the price was likely to be high.

As a method for improving the productivity, Japanese Patent Application Laid-Open
As described in JP-A-205615 and JP-A-1-120510, a method of manufacturing a plurality of optical fiber couplers at one time has been proposed.

However, when manufacturing a plurality of optical fiber couplers at once, it is necessary to make the characteristics of each manufactured optical fiber coupler uniform, but in the conventional manufacturing method, a plurality of optical fiber couplers are required. Since the optical fiber coupler is manufactured by being simultaneously fused and drawn, it has been difficult to manufacture the characteristics uniformly and with good reproducibility.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a method for simultaneously manufacturing a plurality of optical fiber couplers having uniform characteristics. .

[0006]

According to the first aspect of the present invention, the two optical fibers are removed by coating over a predetermined length of each of the two optical fibers to expose the glass optical fibers. The exposed glass optical fibers of the multi-core tape-shaped optical fiber are brought into close contact with each other, heated and fused using a gas burner, and then the fused portion is heated and stretched to simultaneously form a plurality of optical fiber couplers. In the method for manufacturing an optical fiber coupler, the glass optical fiber is a glass optical fiber in the multi-core tape-shaped optical fiber such that a heating gas flow flows evenly between the glass optical fibers. It is characterized in that the film is stretched by heating in a state where it is wider than the interval.

According to a second aspect of the present invention, the glass optical fiber is exposed by removing the coating of each of the two multi-core tape-shaped optical fibers over a predetermined length, and the two multi-core tape-shaped optical fibers are exposed. Manufacturing of optical fiber couplers in which the glass optical fibers with the exposed fibers are brought into contact with each other and bonded by heating using a gas burner, and then the fused portion is heated and stretched to simultaneously form a plurality of optical fiber couplers. In the method, the glass optical fiber is wider than a gap between the glass optical fibers in the multi-core tape-like optical fiber such that a heating gas flow uniformly flows in a gap between every two glass optical fibers. , And is subjected to heat stretching.

According to a third aspect of the present invention, two multi-core tape-like optical fibers are used, in which protective coated optical fibers are arranged one by one at predetermined intervals and integrated with a common coating. Removing the coating of each of the multi-core tape-shaped optical fibers over a predetermined length to expose the glass optical fiber; and exposing the exposed glass optical fiber of the two multi-core tape-shaped optical fibers to the multi-core tape. The glass optical fibers are arranged at the same intervals as the arrangement of the glass optical fibers in the shape of the optical fibers, and the respective glass optical fibers are brought into close contact with each other, and heated and fused using a gas burner. In the method of manufacturing an optical fiber coupler for forming a plurality of optical fiber couplers, the predetermined interval between each of the glass optical fibers in the two multi-core tape-shaped optical fibers is equal to the distance of the glass fiber. It is characterized in that the heating gas flow in the gap of each single optical fiber is a distance obtained by separating the protective coating such that the gap flow uniformly.

According to a fourth aspect of the present invention, two multi-core tape-shaped optical fibers are used, in which two optical fibers each having a protective coating are arranged at a predetermined interval every two fibers and integrated with a common coating. Removing the coating of each of the multi-core tape-shaped optical fibers over a predetermined length to expose the glass optical fiber; and exposing the exposed glass optical fiber of the two multi-core tape-shaped optical fibers to the multi-core tape. The glass optical fibers are arranged at the same intervals as the arrangement of the glass optical fibers in the shape of the optical fibers, and the respective glass optical fibers are brought into close contact with each other, and heated and fused using a gas burner. In the method for manufacturing an optical fiber coupler for forming a plurality of optical fiber couplers, a predetermined interval between every two glass optical fibers in the two multi-core tape-shaped optical fibers is equal to the distance between the glass fibers. It is characterized in that the heating gas flow into the gap by two optical fibers is an interval obtained by separating the protective coating such that the gap flow uniformly.

According to a fifth aspect of the present invention, in the method for manufacturing an optical fiber coupler according to any one of the first to fourth aspects, the gap through which the heated gas flow evenly flows is 250 mm.
μm or more.

[0011]

In the above-described conventional manufacturing method, the coupling degree of the optical fiber couplers manufactured at the same time was measured. As a result, the coupling degree was not uniform, and the coupling degree was different for each optical fiber coupler, and the uniform coupling was obtained. It has been difficult to produce optical fibers of different degrees. In order to clarify the cause, the structure of four optical fiber couplers prototyped using four core optical fibers was investigated in detail. FIG.
FIG. 2 is a cross-sectional view of an example of a core tape-shaped optical fiber, in which four optical fiber cores in which a protective coating 23 is provided on a glass optical fiber having a core 21 and a clad 22 are arranged in a plane. Then, it is covered with a common covering 24 and integrated in a flat shape.

As a result of the investigation, it has been found that the amount of fusion of the optical fiber coupler formed of these optical fiber cores fluctuates greatly as shown in FIG. FIG.
Reference numeral 1 denotes the horizontal axis of the optical fibers of the four-fiber tape-shaped optical fibers in order from the outside, and the vertical axis represents the fusion amount of each glass optical fiber. Fig. 1
As shown in FIG. 2, the width was expressed as the width W of the fused portion of the two glass optical fibers. As shown in FIG. 11, the variation of the fusion amount is such that the fusion amount of the outer glass optical fiber is larger than that of the inner glass optical fiber. Since the amount of fusion greatly depends on the temperature of the glass optical fiber during heating, it is considered from this result that the glass optical fiber is not uniformly heated. Further, as a result of a detailed investigation on this point, it was found that there was a problem in the gas flow at the time of heating the glass optical fiber. In other words, since the interval between the glass optical fibers from which the coating comprising the common coating and the protective coating of the tape-shaped optical fiber has been removed is as narrow as about 125 μm, the gas flow during heating does not sufficiently flow between the glass optical fibers, It is considered that the glass optical fiber cannot be heated evenly.

The heating situation will be described with reference to FIG. In the figure, 1a,
1b, 1c, 1d are glass optical fibers of one tape-shaped optical fiber, 2a, 2b, 2c, 2d are glass optical fibers of the other tape-shaped optical fiber, and 3 is a gas burner. Corresponding respective glass optical fibers 1a and 2a,
1b and 2b, 1c and 2c, 1d and 2d,
It is heated and fused by the gas burner 3. The gas flow at the time of heating does not sufficiently flow between the glass optical fibers, but largely flows outward. Therefore, the gas flow strongly heats only the glass optical fibers at both ends, so that the heating temperature of the glass optical fiber outside is higher than that of the glass optical fiber inside and the fusion amount of the glass optical fiber outside is large. .
This phenomenon is not limited to the case where a tape-shaped optical fiber is used. Even when single-core optical fibers are arranged in close contact, the gap between the glass optical fibers is also about 125 μm, and the same phenomenon occurs.

In the present invention, as shown in FIG.
The gaps between the glass optical fibers of the first glass optical fibers 1a to 1d and the second glass optical fibers 2a to 2d are arranged so that the heating gas flow flows evenly between the glass optical fibers. As a result, a gas flow flows evenly between the glass optical fibers, all the glass optical fibers can be heated uniformly, and an optical fiber coupler having the same characteristics can be obtained. The gap between each glass optical fiber can be 250 μm or more. As shown in FIG. 4, the interval between the glass optical fibers is not limited to making the gas flow evenly flow through the gaps between the glass optical fibers. The gap may be such that the heating gas flow flows evenly in every other gap, that is, every two gaps. In contrast to making the gas flow evenly flow in each of the gaps, making the gas flow evenly flow in every two gaps has the advantage of reducing the overall width of the heating region.

In the present invention, multi-core optical fibers are used as the first and second optical fiber groups. By using the multi-core tape-shaped optical fiber, it is possible to easily perform operations such as arrangement. In this case, the multi-core tape-shaped optical fiber is a tape formed such that the distance (the gap between the glass optical fibers in a state where the coating is removed) of each glass fiber is 250 μm or more, for example. A method of arranging glass optical fibers at the same interval as that of the glass optical fibers in the multi-core tape optical fiber and performing heat drawing using the multi-core optical fiber; There is a method in which only the optical fiber core wires are separated into single cores, and the optical fiber cores are expanded and arranged so that the gap between each glass optical fiber or every two glass optical fibers is, for example, 250 μm or more, and heat stretching is performed.

[0016]

1 is a schematic diagram of an optical fiber coupler manufacturing apparatus used in an embodiment of the optical fiber coupler manufacturing method of the present invention. FIG. 1 (A) is a side view, and FIG. It is a top view. In the figure, 1a to 1d, 2a to 2d are glass optical fibers, 3 is a gas burner, 4a to 4d, 5a to 5d are optical fiber cores, 6a and 6b are optical fiber core fixing jigs,
7a and 7b are glass optical fiber fixing jigs, and 8a and 8b are stretching tables. The glass optical fibers 2a to 2d are:
It is below the glass optical fibers 1a-1d and is not shown in FIG. 1 (B). The optical fiber is a glass optical fiber with a protective coating. This optical fiber is exposed by removing the common coating of the multicore optical fiber.

The first optical fiber cores 4a to 4d and the second optical fiber cores 5a to 5d are stretched by the optical fiber core fixtures 6a and 6b in a state where they are parallel and spaced apart from each other. , 8b. Further, the glass optical fibers 1a to 1d from which the protective coating of the first optical fiber cores 4a to 4d has been removed and the second optical fiber cores 5a to 5d.
Glass optical fibers 2a to 2d from which the protective coating has been removed
Are fixed so as to be in close contact with each other by glass optical fiber fixtures 7a and 7b. Glass optical fiber 1a ~
As described above, the gaps 1d and 2a to 2d are fixed to the gaps between the glass optical fibers so that the heating gas flows uniformly.

In this state, the glass optical fibers 1a to 1d and 2a to 2d are heated by using the gas
a and 2a, 1b and 2b, 1c and 2c, and 1d and 2d are integrated by fusion. Thereafter, the integrated glass optical fibers 1a to 1d and 2a to 2d are heated using the gas burner 4,
The stretching is performed by moving the stretching table 9a to the left and the stretching table 9b to the right. At this time, a laser diode (LD) light source (not shown) is connected to one end of the optical fiber 5a, and a power meter is connected to the opposite side of the optical fibers 5a and 6a.
Monitor the output light. When the intensities of the light emitted from the optical fibers 5a and 6a become equal, the drawing is stopped, and four optical fiber couplers can be manufactured simultaneously.

FIG. 2 is a front view showing a schematic configuration of an example of the glass optical fiber fixture. In the figure, 11 is a main body member, 12 is a pressing member, 13 is a groove, 14 is a spacer,
15 is an axis. The cross sections of the glass optical fibers 1a to 1d and 2a to 2d accommodated in the groove 13 are illustrated. The groove portion 13 in the main body member 11 is formed with a spacer portion 14 in the gap between the glass optical fibers so as to form a gap in which the flow of the heating gas flows evenly. For example, when the outer diameter of the protective coating in the optical fiber core is 250 μm, the diameter of the glass optical fiber is 125 μm, and the gap between the glass optical fibers is 250 μm, the width of the groove 13 is 12 μm.
5 μm, the width of the spacer portion 14 between the groove portions is 250
μm. The groove 13 may be formed by cutting the main body member 11, or the upper surface of the main body member 11 may be made flat and the spacer portion may be formed by a piano wire. Each groove 1
In a state where two glass optical fibers are accommodated in 3, the pressing member 12 is rotated about the shaft 15 so that the glass optical fiber is pressed down from above and fixed.

FIG. 3 is a front view showing a schematic configuration of an example of the optical fiber ribbon fixing device. In the figure, 16 is a main body member,
17 is a pressing member, 18 is a groove, 19 is a spacer, 20
Is the axis. The optical fibers 4a to 4d and 5a to 5d accommodated in the groove 18 are illustrated as having uniform cross sections. The groove 18 in the main body member 16 has a center line
The spacer 19 is formed so as to have an interval corresponding to the center line of the groove of the glass optical fiber fixture. As described above, the outer diameter of the protective coating in the optical fiber core is 250 μm, and the diameter of the glass optical fiber is 125 μm.
When the gap between the glass optical fibers is 250 μm, the width of the groove 18 is 250 μm, and the width of the spacer 19 between the grooves is 125 μm. As in the case of the glass optical fiber fixture, the groove 18 may be formed by cutting the main body member 16, or the upper surface of the main body member 16 may be made flat and the spacer portion 19 may be formed by a piano wire. With the two optical fiber cores stored in each groove part 18, the pressing member 17 is rotated around the shaft 20 to fix the optical fiber core from above.

A first embodiment in which an optical fiber coupler is manufactured using the optical fiber coupler manufacturing apparatus shown in FIG. 1 will be described. Single mode (SM) optical fibers for 1.3 μm band communication were used for the optical fiber cores 4a to 4d and 5a to 5d. Glass optical fibers 1a to 1d, 2a
The gap of ２2d was 250 μm. In the stretching step after fusion, the light source for monitoring the branching ratio has a wavelength of 1.31.
The stretching was stopped when the intensity of the emitted light became equal, as described above, using a μm LD light source. The obtained four optical fiber couplers 1a-2a, 1b-2b, 1c
The degree of coupling was measured at a wavelength of 1.3 μm for each of the optical fiber couplers 2c and 1d-2d. The optical fiber coupler produced an optical fiber coupler having a degree of coupling of 50 ± 2% and uniform characteristics. did it.

In the second embodiment, four optical fiber couplers were manufactured at a time by using the four-core tape-shaped optical fiber by the manufacturing apparatus shown in FIG. The optical fiber used for the tape-shaped optical fiber is a 1.3 μm band communication optical fiber.

FIG. 7 is a sectional view of a four-core tape-shaped optical fiber used in this embodiment. Core 21 and clad 22
The outer diameter of the glass optical fiber consisting of is 125 μm,
The outer diameter of the optical fiber core coated with the protective coating 23 is 250 μm. The optical fibers are arranged in a plane at 375 μm intervals, covered with a common coating 24 and integrated in a flat shape. Therefore, the gap between adjacent protective coatings is 125 μm, and the gap between adjacent claddings is 250 μm.

After removing the coatings of the common coating and the protective coating, the first tape-shaped optical fiber was removed from the four glass optical fibers 1a to 1d having an outer diameter of 125 μm using a 10% hydrofluoric acid solution. The outer diameter was reduced by etching to 115 μm. Glass optical fiber 2a of the second tape-shaped optical fiber
In 2d, the coating is still removed, and the etching process is not performed. The first tape-shaped optical fiber and the second tape-shaped optical fiber are connected to the optical fiber core fixture 6a,
6b, and the upper and lower glass optical fibers were tightly fixed by using glass optical fiber fixtures 7a and 7b. However,
The optical fiber core fixtures 6a and 6b were replaced with those having a structure for fixing the tape-shaped optical fiber shown in FIG. In FIG. 6, 9a and 9b are tape-shaped optical fibers, 16 is a main body member, 17 is a pressing member, and 20 is a shaft. The pressing method using the optical fiber ribbon fixing device is the same as that described with reference to FIG.

The integrated glass optical fibers 1a to 1d,
After heat-sealing 2a to 2d using the gas burner 3,
The stretching table 8a was moved to the left and the stretching table 8b was moved to the right to perform the thermal stretching. At this time, an LD light source having a wavelength of 1.31 μm is connected to one end of the optical fiber 4a, an LD light source having a wavelength of 1.55 μm is connected to one end of the optical fiber 4b, and power is applied to each of the opposite ends of the optical fibers 5a, 5b, 6a, and 6b. The meter was connected. While measuring the output of the power meter, (outgoing light intensity of optical fiber 4a) / (outgoing light intensity of optical fiber 4a + outgoing light intensity of optical fiber 5a) and (outgoing light intensity of optical fiber 4b) / (light The drawing was stopped when the intensity of the output light of the fiber 4b + the output light intensity of the optical fiber 5b) became equal.

The obtained four optical fiber couplers 1a-2
The binding degree was measured for a, 1b-2b, 1c-2c, 1d-2d. For any optical fiber coupler,
The degree of coupling at a wavelength of 1.31 μm is 50 ± 2%, 1.55 μm.
The degree of coupling of m was 50 ± 2%, and it was confirmed that uniform characteristics were exhibited at any wavelength.

The optical fiber coupler manufactured in the second embodiment is a broadband optical fiber coupler having a wavelength of 1.31 μm and a coupling degree equal to 1.55 μm. Conventionally, in the extension of this type of optical fiber coupler, it is necessary to connect a plurality of light sources and light receivers to a single optical fiber core using a multiplexer / demultiplexer in order to extend while monitoring light of a plurality of wavelengths simultaneously. was there. On the other hand, in the manufacturing method of the present invention,
At the same time, optical fiber couplers with the same characteristics can be manufactured.
Attaching one light source and one light receiver to each of a plurality of optical fibers allows monitoring characteristics of a plurality of wavelengths without using a multiplexer / demultiplexer, and has an advantage that a complicated monitor system does not need to be configured.

In the second embodiment, one of the glass optical fibers is etched to have a small diameter as a means for broadening the degree of coupling of the optical fiber coupler. However, another method generally known, for example, A method using optical fibers having different element diameters, a method in which one of the optical fiber groups is drawn in advance, a method using optical fibers having different core diameters, a method using optical fibers having different core refractive indices, etc. may be applied. Can be.

In the third embodiment, the cutoff is 0.75
An optical fiber coupler was manufactured by the manufacturing apparatus shown in FIG. 1 using a four-core tape-shaped optical fiber obtained by tapering an SM optical fiber core having a diameter of 125 μm, a wire diameter of 125 μm, and a coating diameter of 250 μm. In this embodiment, since the tape-shaped optical fiber has a normal tape-shaped optical fiber structure, it is necessary to widen the gap between the glass optical fibers at the portion where the coating is removed to 250 μm. Then, the tape-shaped optical fibers before and after the coating removal section are separated into single-core optical fibers, and then the optical fiber core fixing members 6a and 6b and the glass optical fiber fixing member 7 are separated.
Arrayed using a and 7b, fusing and stretching were performed. The optical fiber fixing device is the same as that described in FIG. 3, and the glass optical fiber fixing device is the same as that described in FIG.

At the time of stretching, an LD light source having a wavelength of 0.85 μm is connected to one end of the optical fiber 4a, and an optical power meter is connected to the opposite ends of the optical fibers 4a and 5a. The drawing was completed when the intensity of light emitted from the optical fibers 4a and 5a became equal. As a result of measuring the coupling degree of the obtained optical fiber coupler at a wavelength of 0.85 μm, it was confirmed that the coupling degree was 50 ± 2% in all the optical fiber couplers, and that the optical fiber coupler had uniform characteristics.

In the fourth embodiment, eight optical fiber couplers were manufactured at one time using eight tape-shaped optical fibers as optical fibers by the manufacturing apparatus shown in FIG. The optical fiber core used for the tape-shaped optical fiber is 1.3.
This is an optical fiber for communication in the μm band. In this embodiment, since a tape-shaped optical fiber having a normal structure was used, the tape-shaped optical fibers before and after the coating removal portion were separated into single-core optical fibers, and then the optical fiber core fixing members 6a and 6b and the glass were fixed. They were arranged using the optical fiber fixtures 7a and 7b.

The outer diameter of the glass optical fiber of the eight-core tape-shaped optical fiber used in this embodiment is 125 μm, and the outer diameter of the optical fiber coated with a protective coating is 25 μm.
0 μm. The arrangement of the optical fibers is such that the gap between every other glass optical fiber is 250 μm or more, for example, 500 μm.
m.

FIG. 9 is a front view showing a schematic configuration of an example of a glass optical fiber fixture, and FIG. 10 is a front view showing a schematic configuration of an example of an optical fiber core fixture. In the figure, parts corresponding to those in FIGS. 2 and 3 are denoted by the same reference numerals, and description thereof is omitted. Since the two optical fibers are fixed so that the coating is in contact with each other, the gap between the glass optical fibers is 125 μm. The distance between the two optical fibers is fixed at 625 μm at the center-to-center distance and 375 μm in the gap between the protective coatings. Therefore, the gap between the glass optical fibers between them is 500 μm. .

In this state, fusion and stretching were performed. In the stretching step, one end of the optical fiber 4a has a wavelength of 1.55 μm.
Is connected, and a power meter is connected to the opposite ends of the optical fibers 4a and 5a, and the drawing is performed while monitoring the output light intensity. When the output light intensity of the optical fibers 4a and 5a becomes equal, the drawing is performed. Finished. As a result of measuring the degree of coupling at a wavelength of 1.55 μm with respect to the obtained eight optical fiber couplers, the degree of coupling was 50 ± 2% in all the optical fiber couplers, and uniform characteristics were obtained. confirmed.

[0035]

As is apparent from the above description, according to the present invention, a plurality of optical fiber couplers having the same characteristics can be manufactured by one fusion / stretching. This has the effect that the productivity of the optical fiber coupler can be dramatically improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an optical fiber coupler manufacturing apparatus used in an embodiment of an optical fiber coupler manufacturing method according to the present invention.

FIG. 2 is a front view schematically showing an example of a glass optical fiber fixture.

FIG. 3 is a front view schematically showing an example of an optical fiber core fixing device.

FIG. 4 is an explanatory diagram of a heating state in the embodiment of the present invention.

FIG. 5 is an explanatory diagram of a heating state in a conventional manufacturing method.

FIG. 6 is a front view schematically showing an optical fiber ribbon fixing tool used in the embodiment of the present invention.

FIG. 7 is a sectional view of an example of a tape-shaped optical fiber used in the present invention.

FIG. 8 is a cross-sectional view of another example of the tape-shaped optical fiber used in the present invention.

FIG. 9 is a front view schematically showing an example of a glass optical fiber fixture used in a fourth embodiment of the present invention.

FIG. 10 is a front view schematically showing an example of an optical fiber ribbon fixing tool used in a fourth embodiment of the present invention.

FIG. 11 is an explanatory diagram showing a fusion amount by a conventional fusion method.

FIG. 12 is an explanatory diagram of a fusion amount.

[Explanation of symbols]

1a to 1d, 2a to 2d: glass optical fiber, 3: gas burner, 4a to 4d, 5a to 5d: optical fiber, 6a,
6b: optical fiber core fixing jig, 7a, 7b: glass optical fiber fixing jig, 8a, 8b: stretching table, 9a, 9b ...
Tape-like optical fiber, 11: body member, 12: pressing member, 13: groove, 14: spacer.

Continued on the front page (72) Inventor Hiroaki Takimoto 1st Tanicho, Sakae-ku, Yokohama-shi, Kanagawa Prefecture Sumitomo Electric Industries, Ltd. Yokohama Works (72) Inventor Hiroshi Yokota 1st Tanimachi, Sakae-ku, Yokohama-shi, Kanagawa Sumitomo Electric Industries, Ltd. Yokohama (56) References JP-A-63-205615 (JP, A) JP-A-2-24607 (JP, A) JP-A-2-187708 (JP, A) (58) Fields investigated (Int. . ⁶ , DB name) G02B 6/28

Claims (5)

(57) [Claims] 1. A glass light having two multi-core tape-shaped optical fibers, the coating of which is removed over a predetermined length to expose a glass optical fiber, and the two multi-core tape-shaped optical fibers are exposed. In a method for manufacturing an optical fiber coupler, the fibers are brought into close contact with each other and heated and fused using a gas burner, and then the fused portion is heated and stretched to simultaneously form a plurality of optical fiber couplers. In the multi-core optical fiber, the heating and stretching are performed so as to be wider than the gap between the glass optical fibers in the multi-core tape-shaped optical fiber so that the heating gas flows uniformly in the gap between the glass optical fibers. The manufacturing method of the optical fiber coupler characterized by the above-mentioned. 2. A glass light having two multi-core tape-shaped optical fibers, the coating of which is removed over a predetermined length to expose the glass optical fiber, and the two multi-core tape-shaped optical fibers are exposed. In a method for manufacturing an optical fiber coupler, the fibers are brought into close contact with each other and heated and fused using a gas burner, and then the fused portion is heated and stretched to simultaneously form a plurality of optical fiber couplers. The heating and drawing are performed in a state where the gap is wider than the interval between the glass optical fibers in the multi-core tape-shaped optical fiber so that the gap between the glass optical fibers in each of the two optical fibers flows uniformly. The manufacturing method of the optical fiber coupler characterized by the above-mentioned. 3. A multi-core tape-like optical fiber comprising two multi-core tape-shaped optical fibers in which protective coatings are arranged at predetermined intervals one by one and integrated with a common coating. Each of the fibers is stripped of coating over a predetermined length to expose the glass optical fiber, and the exposed glass optical fiber of the two multi-core tape optical fibers is replaced with the glass optical fiber in the multi-core tape optical fiber. Arranged at the same interval as the arrangement interval of each other, each glass optical fiber is brought into close contact with each other, heated and fused using a gas burner, and the fused portion is heated and stretched, simultaneously forming a plurality of optical fiber couplers In the method of manufacturing an optical fiber coupler described above, the predetermined interval between each of the glass optical fibers in the two multi-core tape-shaped optical fibers is equal to the predetermined interval between each of the glass optical fibers. A method for manufacturing an optical fiber coupler, wherein the gap is such that a protective coating is separated so that a gap in which a heating gas flow flows evenly in the gap. 4. A multi-core tape-like optical fiber comprising two multi-core tape optical fibers in which protective coatings are arranged at predetermined intervals for every two fibers and integrated with a common coating. Each of the fibers is stripped of coating over a predetermined length to expose the glass optical fiber, and the exposed glass optical fiber of the two multi-core tape optical fibers is replaced with the glass optical fiber in the multi-core tape optical fiber. Arranged at the same interval as the arrangement interval of each other, each glass optical fiber is brought into close contact with each other, heated and fused using a gas burner, and the fused portion is heated and stretched, simultaneously forming a plurality of optical fiber couplers In the method for manufacturing an optical fiber coupler described above, the predetermined interval between every two glass optical fibers in the two multi-core tape-shaped optical fibers is set every two glass optical fibers. A method for manufacturing an optical fiber coupler, wherein the gap is such that a protective coating is separated so that a gap in which a heating gas flow flows evenly in the gap. 5. A gap, in which the flow of the heating gas flows evenly, is 2
5. The structure according to claim 1, wherein the thickness is 50 μm or more.
The method for manufacturing an optical fiber coupler according to any one of the above items.