JP5902016B2 - Optical fiber end cap joint structure and manufacturing method thereof - Google Patents

Description

  The present invention relates to an optical fiber end cap joining structure and a manufacturing method thereof.

  In an optical fiber that transmits, or oscillates or amplifies, high-power and high-density laser light, an end cap is bonded to the fiber end face in order to improve laser resistance of the fiber end face.

  Patent Document 1 discloses an optical fiber structure in which an end cap of a block-shaped chip is joined to an optical fiber, and the end cap is formed in a tapered shape toward a fiber coupling side end. .

JP 2007-279291 A

  When joining an end cap to an optical fiber, an amount of heat necessary for melt joining is supplied from the outside to a region including the joint portion of the end cap. Specifically, for example, the region including the joint portion of the end cap is locally irradiated with laser light to be melted by applying heat to the optical fiber. However, when heat is applied from the outside in this way, heat is also applied to the optical fiber side. When heat is applied more than necessary, the optical fiber usually has a smaller heat capacity than the end cap. The tip melts faster and deforms before joining, thereby deforming the core of the fiber end face on the joining side of the optical fiber. For example, if it is used as the exit end, the emitted light pattern is distorted. There is.

  An object of the present invention is to provide an optical fiber end cap bonding structure in which deformation of a core of a fiber end face on the bonding side of an optical fiber is suppressed.

The present invention provides an optical fiber / end cap bonding structure in which a fiber end surface of an optical fiber exposed by peeling off a coating layer at one fiber end of an optical fiber core wire is melt bonded to an end cap. the joint end portion with the coated and optical fiber example Bei the shield in the molten bonding is abutted against the end cap, the junction area to the end cap of the covering member, to the end caps of the optical fiber The covering member is only in contact with the outer peripheral portion of the optical fiber and is not fused and integrated .

The present invention is a method of manufacturing an optical fiber end cap bonding structure according to the present invention, wherein a covering member is provided so as to cover a bonding side end portion of an optical fiber, while an end cap bonding planned portion is externally provided. Heat is applied to melt, and the covering member is abutted together with the optical fiber on the melted joint portion of the end cap to be melt bonded.

  According to the present invention, since the covering member provided so as to cover the end portion on the joining side together with the optical fiber is melt-bonded to the end cap, the covering member increases the heat capacity on the optical fiber side, thereby joining the end cap. It is possible to suppress the deformation of the core of the fiber end face on the optical fiber joining side due to the heat of time.

It is a perspective view of the optical fiber end cap joining structure concerning an embodiment. (A) And (b) is a perspective view of an optical fiber. It is a perspective view of the modification of an optical fiber. (A) And (b) is a perspective view of the other modification of an optical fiber. It is a perspective view of an end cap. (A)-(e) is a perspective view of a coating | coated member. (A)-(c) is explanatory drawing of the manufacturing method of the optical fiber end cap junction structure which concerns on embodiment. (A) And (b) is a figure which shows the emitted light pattern of the laser beam containing a radiation pattern. (A) And (b) is a figure which shows the emitted light pattern of the favorable laser beam which does not contain a radiation pattern.

  Hereinafter, embodiments will be described in detail with reference to the drawings.

  FIG. 1 shows an optical fiber end cap joining structure 10 according to an embodiment. The optical fiber / end cap joining structure 10 according to the present embodiment is a structure configured at an emission end or an incidence end of an optical fiber component such as a laser guide for a processing apparatus.

  An optical fiber / end cap joining structure 10 according to the present embodiment includes an optical fiber core wire 100 and an end cap 20.

  2A and 2B show the optical fiber core wire 100. FIG.

  The optical fiber core 100 includes an optical fiber 110 and a coating layer 120 formed of, for example, a UV curable resin that covers the optical fiber 110. When used in a laser guide application, the length of the optical fiber core wire 100 is, for example, 5 to 300 m.

  The optical fiber 110 includes a core 111 having a high refractive index that forms the center of the fiber and a cladding 112 having a low refractive index that is provided so as to cover the core. The cross-sectional shape of the optical fiber 110 is typically circular, but may be elliptical. The fiber diameter of the optical fiber 110 is, for example, 100 to 2000 μm, and is preferably 100 to 750 μm, and more preferably 100 to 500 μm, from the viewpoint that the effect of suppressing deformation of the core 111 described later is remarkable.

  The core 111 is made of, for example, pure quartz or quartz doped with various dopants (such as rare earth elements such as Er, Yb, and Nd). In that case, the refractive index is 1.458. The cross-sectional shape of the core 111 may be circular as shown in FIG. 2A, and in that case, the core diameter is, for example, 50 to 1200 μm. Further, the cross-sectional shape of the core 111 may be a square as shown in FIG. 2B, and in that case, the length of one side is, for example, 50 to 1000 μm.

  The clad 112 is made of, for example, quartz doped with fluorine, boron, or the like that lowers the refractive index. In this case, the refractive index is, for example, 1.440 to 1.454. The cross-sectional shape of the cladding 112 usually corresponds to the cross-sectional shape of the optical fiber 110, but is typically circular. The layer thickness of the clad 112 is, for example, 3 to 90 μm.

  As shown in FIG. 3, the optical fiber 110 may be a double-clad optical fiber having an inner cladding 112a and an outer cladding 112b in which the cladding 112 forms a pump guide.

  The entire optical fiber 110 is made of, for example, pure quartz or quartz doped with various dopants, and, as shown in FIG. 4A, a plurality of air arranged so as to surround the core 111. It may be provided with a clad 112 in which a hole 113 is formed, and as shown in FIG. 4B, an inner clad constituting a core 111 and a pump guide provided so as to cover the core 111 It may be a double clad optical fiber including 112a and an outer clad 112b in which a plurality of air holes 113 arranged so as to surround the air hole 113b are formed.

  The optical fiber 110 may have a support layer provided so as to cover the clad 112. In this case, the support layer is preferably made of, for example, pure quartz, like the core 111, in which case the refractive index is 1.458. The layer thickness of the support layer is, for example, 5 to 60 μm.

  FIG. 5 shows an example of the end cap 20.

The end cap 20 is made of, for example, pure quartz or quartz doped with various dopants, but prevents the formation of an interface that reflects light between the end cap 20 and the core 111 of the optical fiber 110. From the viewpoint, it is preferable that the optical fiber 110 is formed of the same material as the core 111. The shape of the end cap 20 is not particularly limited, and may be a block shape such as a cylinder as shown in FIG. 4, and has a bottleneck shape portion as disclosed in Patent Document 1. It may be. The cap end surface on the incident end side or the emission end side of the end cap 20 is, for example, an HfO ₂ —SiO ₂ film, a Ta ₂ O ₅ —SiO ₂ film, an Al ₂ O ₃ —SiO ₂ film, or an Nb ₂ O ₅ —SiO ₂ film. It may be coated with an AR coating (Anti Reflection coating) such as a film. The side surface of the end cap 20 may be roughened by processing such as sandblasting. In this case, stray light or the like incident from the outside can be released to the outside without being reflected inside. For example, in the case of the cylindrical shape shown in FIG. 4, the end cap 20 has a length of 5 to 50 mm and an outer diameter of 3 to 40 mm.

  In the optical fiber end cap joining structure 10 according to the present embodiment, the coating layer 120 is peeled off by about 10 to 150 mm, for example, at one fiber end of the optical fiber core wire 100 to expose the optical fiber 110, and the exposed light. The fiber end surface of the fiber 110 has a configuration in which the end cap 20 is melt-bonded. The optical fiber / end cap joining structure 10 according to the present embodiment includes a covering member 30 that covers the joining side end portion of the optical fiber 110, and the covering member 30 is melt bonded to the end cap 20 together with the optical fiber 110. It has a configuration.

  According to the optical fiber / end cap joining structure 10 according to the present embodiment, the covering member 30 provided so as to cover the end portion on the joining side together with the optical fiber 110 is melt-bonded to the end cap 20. The heat capacity on the optical fiber 110 side is increased by the member 30, and thereby deformation of the core 111 on the fiber end surface on the bonding side of the optical fiber 110 due to heat at the time of bonding described later can be suppressed.

  6A to 6E show the covering member 30. FIG.

  The covering member 30 is made of, for example, pure quartz or quartz doped with a metal that lowers the softening point. The covering member 30 may be made of the same material as the end cap 20. The softening point of the covering member 30 may be the same as the softening point of the end cap 20, may be lower than the softening point of the end cap 20, or may be higher than the softening point of the end cap 20. Good.

  The shape of the covering member 30 is not particularly limited. For example, the covering member 30 is formed in a cylindrical shape having a through hole 31 into which an optical fiber 110 as shown in FIG. 6A can be fitted. In this case, for example, the outer diameter is 0.5 to 2 mm and the height is 5 to 150 mm. Further, the cylindrical covering member 30 is formed of a truncated cone tapered in the direction in which the optical fiber 110 extends from the joint with the end cap 20 as shown in FIG. 6B or a pyramid as shown in FIG. It may be formed in the shape of a stand or the like.

  The shape of the covering member 30 may be formed in a disk shape in which a through hole 31 into which an optical fiber 110 can be fitted as shown in FIG. 6D is formed. Is 0.5 to 2 mm and the thickness is 0.5 to 5 mm.

  The shape of the covering member 30 may be formed in a strip shape so as to cover the optical fiber 110 as shown in FIG. 6E from the side. In this case, for example, the thickness is 0.5 to 2 mm. is there.

  The covering member 30 is bonded to the end cap 20 together with the optical fiber 110. From the viewpoint of suppressing the deformation of the core 111 on the fiber end surface on the bonding side of the optical fiber 110 by increasing the heat capacity on the optical fiber 110 side, the bonding area is covered. In other words, the contact area with the end cap 20 is preferably larger than the bonding area of the optical fiber 110 to the end cap 20. Specifically, the bonding area of the covering member 30 is preferably 2 to 10 times, more preferably 2 to 4 times the bonding area of the optical fiber 110.

  The covering member 30 may be in an aspect in which the covering member 30 is only in contact with the outer peripheral portion of the optical fiber 110 and is not melt-integrated. There may be. From the viewpoint of suppressing the deformation of the core 111, the former configuration in which heat more than necessary is not applied to the optical fiber 110 is preferable.

  Next, the optical fiber end cap joining structure 10 according to the present embodiment will be described with reference to FIGS.

  First, the optical fiber core wire 100 and the end cap 20 are prepared, and the coating layer 120 on the bonding side of the optical fiber core wire 100 is peeled off for a predetermined length to expose the optical fiber 110.

  Next, the fiber end surface on the bonding side of the optical fiber 110 and the bonding surface 21 of the end cap 20 are optically polished. Here, examples of the optical polishing means include polishing with an abrasive and flame irradiation.

  Subsequently, as illustrated in FIG. 7A, a covering member 30 is provided so as to cover the joining side end portion of the optical fiber 110.

Next, as shown in FIG. 7B, an optical fiber in which a laser beam is irradiated obliquely from the lateral direction with respect to the joining surface 21 of the end cap 20 and a covering member 30 is provided on the joining surface 21 of the end cap 20. 110 is brought into contact with each other. At this time, the surface layer portion of the joint surface 21 of the end cap 20 is melted, and the optical fiber 110 and the covering member 30 are brought into contact with the melted joint surface 21 of the end cap 20 and melt-bonded. Here, from the viewpoint of suppressing deformation of the core 111 on the fiber end surface on the bonding side of the optical fiber 110, it is preferable that the bonding surfaces of the optical fiber 110 and the covering member 30 are not melted by heating. Examples of the laser light source include a CO ₂ laser, and the wavelength of the laser light is preferably 5 to 11 μm. The laser light irradiation may be performed with the joining surface 21 of the end cap 20 set as a horizontal plane, or may be performed with the joining surface 21 of the end cap 20 set as a vertical plane. Irradiation with laser light may be performed from one direction or from a plurality of directions.

  Then, as shown in FIG. 7C, the laser beam irradiation is stopped and cooled simultaneously with the contact of the optical fiber 110 and the covering member 30 with the joining surface 21 of the end cap 20, and this embodiment is concerned. An optical fiber end cap joining structure 10 is configured.

  By the way, in the configuration in which the optical fiber 110 is melt-bonded to the end cap 20 without using the covering member 30 as in the prior art, at the time of bonding, the tip of the optical fiber 110 is melted earlier and deformed before bonding. As a result, the core 111 on the fiber end face on the joining side of the optical fiber 110 is also deformed. For example, when laser light is emitted with the end cap 20 as the emission end, if the cross-sectional shape of the core 111 is circular, FIG. As shown in a), if the cross-sectional shape of the core 111 is a square, an outgoing light pattern P including a radiation pattern r may be obtained as shown in FIG. 8B. However, according to the optical fiber / end cap joining structure 10 according to the present embodiment, the covering member 30 provided so as to cover the joining side end portion together with the optical fiber 110 is melt-joined to the end cap 20. The heat capacity on the optical fiber 110 side is increased by the covering member 30, whereby deformation of the core 111 on the fiber end surface on the bonding side of the optical fiber 110 due to heat at the time of bonding can be suppressed. As a result, for example, even when laser light is emitted with the end cap 20 as the emission end, if the cross-sectional shape of the core 111 is circular, the cross-sectional shape of the core 111 is square as shown in FIG. Then, as shown in FIG. 9B, a good outgoing light pattern P that does not include a radiation pattern can be obtained.

  In the present embodiment, the optical fiber 110 and the end cap 20 are joined by using laser light as a heat source. However, the present invention is not particularly limited to this. The joining surface 21 of the end cap 20 may be melted by using as a heat source.

(Test 1)
<Comparative Example 1>
An optical fiber core A including a quartz optical fiber having a fiber diameter of 500 μm and a core diameter of 200 μm, and a quartz optical fiber having a fiber diameter of 750 μm and a core diameter of 500 μm, having the same configuration as shown in FIG. And an optical fiber core C having an optical fiber made of quartz having a fiber diameter of 1000 μm and a core diameter of 750 μm, a length of 15 mm and an outer diameter of the same configuration as shown in FIG. Three 8 mm cylindrical end caps made of quartz were prepared.

  For each of the optical fiber cores A to C, the coating layer on the bonding side was peeled off for a predetermined length to expose the optical fiber, and the fiber end surface on the bonding side was optically polished. Also, one surface (bonding surface) of each end cap was optically polished.

A laser beam having a wavelength of 10.6 μm from a CO ₂ laser is irradiated from an oblique lateral direction to the joining surface of the end cap subjected to optical polishing to melt the surface layer portion, and the optical fiber of the optical fiber core A is abutted there. At the same time, the laser beam was cut off. As a result, an optical fiber end cap joining structure of the optical fiber core A was obtained. Similarly, optical fiber end cap joining structures of optical fiber cores B and C were obtained.

  For each of the optical fiber end cap joint structures of these optical fiber cores A to C, when the joint portion between the optical fiber and the end cap was observed, a form in which the side surface portion at the tip of the optical fiber was slightly deformed was recognized. It was. In the optical fiber end cap joint structure of the optical fiber core wire B having a fiber diameter of 750 μm and the optical fiber core wire C having a fiber diameter of 1000 μm, although deformation of the cladding of the optical fiber was observed, deformation of the core was not recognized. It was. On the other hand, in the optical fiber end cap junction structure of the optical fiber core wire A having a fiber diameter of 500 μm, not only the cladding of the optical fiber but also the deformation of the core was recognized.

  For each of the optical fiber end cap joint structures of the optical fiber cores A to C, the laser beam having a wavelength of 633 nm from the He—Ne laser was transmitted to the optical fiber, and the emitted light pattern obtained through the end cap was evaluated. However, in the optical fiber end cap joining structure of the optical fiber core B having a fiber diameter of 750 μm and the optical fiber core C having a fiber diameter of 1000 μm, an outgoing light pattern without distortion as shown in FIG. P was obtained. On the other hand, in the optical fiber end cap junction structure of the optical fiber core A having a fiber diameter of 500 μm, an outgoing light pattern P including a radiation pattern r as shown in FIG.

<Example 1>
An optical fiber core A comprising a quartz optical fiber having a fiber diameter of 500 μm and a core diameter of 200 μm having the same configuration as shown in FIG. 2A, a length of 15 mm and an outer configuration having the same configuration as shown in FIG. A cylindrical quartz end cap having a diameter of 8 mm and a cylindrical quartz covering member having an outer diameter of 1000 μm, an inner diameter of 500 μm, and a length of 2 mm having the same configuration as shown in FIG. 6A were prepared.

  The coating layer on the bonding side of the optical fiber core A was peeled for a predetermined length to expose the optical fiber, and the fiber end surface on the bonding side was optically polished. Also, one surface (bonding surface) of the end cap was optically polished.

As in the above embodiment, the joint end of the exposed optical fiber is fitted on the covering member to cover the end surface, and the end cap is subjected to optical polishing with a laser of 10.6 μm wavelength from the CO ₂ laser. The surface layer portion was melted by irradiating light obliquely from the lateral direction, and the optical fiber of the optical fiber core A and the covering member were brought into contact with each other, and at the same time, the laser beam irradiation was cut off. As a result, an optical fiber end cap joining structure of the optical fiber core A using the covering member was obtained.

  With respect to the optical fiber end cap bonding structure of the optical fiber core A using this covering member, no deformation of the core was observed when the bonded portion between the optical fiber and the end cap was observed. In addition, when a laser beam having a wavelength of 633 nm from a He—Ne laser was transmitted to an optical fiber and an emitted light pattern obtained through an end cap was evaluated, a good output without distortion as shown in FIG. 9A was obtained. A light emission pattern P was obtained.

  Also, an optical fiber core C having an optical fiber made of quartz having a fiber diameter of 1000 μm and a core diameter of 750 μm having the same configuration as shown in FIG. 2A, and a length of 15 mm having the same configuration as shown in FIG. And a cylindrical quartz end cap having an outer diameter of 8 mm, and a cylindrical quartz covering member having an outer diameter of 1400 μm, an inner diameter of 1000 μm, and a length of 2 mm having the same configuration as shown in FIG. The same test results were obtained for the optical fiber end cap joint structure.

(Test 2)
<Comparative Example 2>
An optical fiber core D having an optical fiber made of quartz having a square core with a fiber diameter of 500 μm and 50 μ × 150 μm having the same configuration as shown in FIG. 2B, and the same as shown in FIG. A cylindrical quartz end cap having a length of 15 mm and an outer diameter of 8 mm was prepared.

  The coating layer on the bonding side of the optical fiber core A was peeled off for a predetermined length to expose the optical fiber, and the fiber end face was optically polished. Also, one surface (bonding surface) of the end cap was optically polished.

The optically polished end cap is irradiated with laser light having a wavelength of 10.6 μm from a CO ₂ laser in an oblique lateral direction to melt the surface layer portion, and the optical fiber of the optical fiber core D is abutted there. At the same time, the laser beam was cut off. As a result, an optical fiber end cap joining structure of the optical fiber core D was obtained.

  With respect to the optical fiber end cap joint structure of the optical fiber core D, when the joint between the optical fiber and the end cap was observed, deformation of the tip of the optical fiber was observed. Although the above trial was repeated a plurality of times, there was a case where the tip of the optical fiber was deformed at the time of joining, or the tip of the optical fiber was deformed by melting before joining, and joining was impossible.

  With respect to the optical fiber end cap joint structure of the optical fiber core D, when the laser beam having a wavelength of 633 nm from the He—Ne laser is transmitted to the optical fiber and the emitted light pattern obtained through the end cap is evaluated, FIG. An outgoing light pattern P including a radiation pattern r as shown in (b) was obtained.

<Example 2>
An optical fiber core D having an optical fiber made of quartz having a fiber core of 500 μm and a square core of 50 μ × 150 μm having the same configuration as shown in FIG. 2B, the same configuration as shown in FIG. A cylindrical quartz end cap having a length of 15 mm and an outer diameter of 8 mm, and a cylindrical quartz end cap having the same configuration as shown in FIG. 6A and an outer diameter of 1000 μm, an inner diameter of 500 μm, and a length of 2 mm. A covering member was prepared.

  The coating layer on the bonding side of the optical fiber core A was peeled off for a predetermined length to expose the optical fiber, and the fiber end face was optically polished. Also, one surface (bonding surface) of the end cap was optically polished.

As in the above embodiment, the joint end of the exposed optical fiber is fitted on the covering member to cover the end surface, and the end cap is subjected to optical polishing with a laser of 10.6 μm wavelength from the CO ₂ laser. The surface layer portion was melted by irradiating light obliquely from the lateral direction, and the optical fiber of the optical fiber core D and the covering member were brought into contact with each other, and at the same time, the irradiation of the laser beam was cut off. As a result, an optical fiber end cap joining structure of the optical fiber core D using the covering member was obtained.

  With respect to the optical fiber end cap bonding structure of the optical fiber core D using this covering member, when the bonded portion between the optical fiber and the end cap was observed, no deformation of the core was observed. In addition, when a laser beam having a wavelength of 633 nm from a He—Ne laser was transmitted to an optical fiber and an emitted light pattern obtained through an end cap was evaluated, a good output without distortion as shown in FIG. 9B was obtained. A light emission pattern P was obtained.

(Test 3)
<Example 3>
An optical fiber core including a double clad optical fiber made of quartz in which Yb is doped in a core having a fiber diameter of 1000 μm, a core diameter of 60 μm, and a pump guide diameter of 600 μm inside the air hole, having the same configuration as shown in FIG. Line E, two cylindrical quartz end caps having a length of 15 mm and an outer diameter of 8 mm having the same configuration as shown in FIG. 5, and an outer diameter of 1000 μm having the same configuration as shown in FIG. Two cylindrical quartz covering members having an inner diameter of 500 μm and a length of 2 mm were prepared.

  The coating layers on both sides of the optical fiber core E were peeled for a predetermined length to expose the double-clad optical fiber, and each fiber end face was optically polished. Also, one surface (bonding surface) of each end cap was optically polished.

As in the above embodiment, each of the joint-side end portions of both exposed double-clad optical fibers is covered with a covering member and covered, and the end cap is optically polished for each joint-side end portion. The joint surface is irradiated with laser light having a wavelength of 10.6 μm from a CO ₂ laser from an oblique lateral direction to melt the surface layer portion, and the double-clad optical fiber of the optical fiber core E and the covering member are abutted there. At the same time, the laser beam was cut off. As a result, an optical fiber component in which the optical fiber end cap joining structure of the optical fiber core E using the covering members at both ends was formed was obtained.

  When this optical fiber component was observed at the joint between the double clad optical fiber and the end cap, neither deformation of the tip of the optical fiber nor deformation of the air hole was observed.

  In addition, when a laser oscillator was configured by combining this optical fiber component and an external resonator mirror, and a laser oscillation experiment was performed using the laser oscillator, it was the same as the case of the optical fiber core E alone with no end cap bonded. The oscillation characteristics were confirmed. That is, this means that the structure in which the double clad optical fiber is bonded to the end cap using the covering member does not adversely affect the laser oscillation characteristics. In addition, if an optical fiber component in which a double-clad optical fiber is joined to an end cap using this covering member is used, the end cap end surface, which is the laser light emitting end surface, is not destroyed even when kW-class laser oscillation is performed. It was also confirmed that highly reliable laser oscillation was performed.

  INDUSTRIAL APPLICABILITY The present invention is useful for an optical fiber end cap joining structure and a manufacturing method thereof.

DESCRIPTION OF SYMBOLS 100 Optical fiber end cap junction structure 110 Optical fiber core wire 110 Optical fiber 111 Core 112 Clad 112a Inner clad 112b Outer clad 113 Air hole 120 Cover layer 20 End cap 21 Joint surface 30 Cover member 31 Through-hole

Claims (5)

An optical fiber end cap bonding structure in which the fiber end surface of the optical fiber exposed by peeling off the coating layer at one fiber end of the optical fiber core is melt bonded to the end cap,
E Bei the shield in the molten bonding is abutted against the end cap of the connecting-side end portion with coated and optical fiber of the optical fiber,
The bonding area of the covering member to the end cap is larger than the bonding area of the optical fiber to the end cap,
An optical fiber end cap joining structure in which the covering member is only in contact with the outer peripheral portion of the optical fiber and is not fused and integrated . In the optical fiber end cap joining structure according to claim 1,
The said covering member is an optical fiber end cap joining structure currently formed in the cylinder shape in which the through-hole which can fit the said optical fiber was formed. In the optical fiber end cap joining structure according to claim 1 or 2,
The covering member is an optical fiber / end cap joining structure formed in a shape tapered from a joint portion with the end cap in a direction in which the optical fiber extends. In the optical fiber end cap joining structure according to any one of claims 1 to 3,
The covering member is an optical fiber / end cap joining structure formed of the same material as the end cap. A method for manufacturing an optical fiber endcap joining structure according to any one of claims 1 to 4 ,
A covering member is provided so as to cover the end portion of the optical fiber on the bonding side, while the end cap joining portion of the end cap is melted by applying heat from the outside, and the end portion of the end cap is melted with the light. A method of manufacturing an optical fiber end cap bonding structure in which a coating member is abutted with a fiber and melt-bonded.

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