JP2000298224A - End-surface processing method for optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To actualize an end-surface processing method for optical fiber which will not impair optical transmission capability and eliminates the need for controlling the projection length of the tip of an optical fiber as before. SOLUTION: This method is adopted which has a process for inserting an optical fiber 10 into a guide hole 12 as the columnar space formed in a ferrule 13 as an optical fiber hold part and holding it at right angles to a heating surface 11, a process for arranging a filler 14 having a same refractive index with the core of the optical fiber 10 between an end surface 10a and the heating surface 11, and a process for pressing a tip peripheral edge 12a formed at the tip in the ferrule 13 on the side of the heating surface 11, in contact with the heating surface 11 and depositing the filler 14 on the end surface 10a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating an end face of a plastic optical fiber used for optical transmission.

[0002]

2. Description of the Related Art An optical fiber made of plastic is obtained by covering a core made of a fiber such as methacrylic resin with a cladding made of fluorinated methacrylic resin having a lower refractive index than the core. It is used as a light guide and the like. When applying this type of optical fiber to optical transmission, it is required to treat the end face as smooth as possible. That is, if the end face is rough, the transmitted light causes irregular reflection and causes optical loss. Therefore, it is necessary to smooth the end face to minimize the loss.

[0003] The main methods of such finishing methods include, for example, a polishing treatment method for smoothing by polishing the end face, a free cutting treatment method for smoothing by cutting the end face, and a smoothing method for smoothing the end face. There is a hot plate treatment method for smoothing by pressing against a heated surface. The polishing method is
Although it has the advantage of obtaining a smooth surface with high accuracy, it also has the disadvantage of requiring a long processing time. Further, the free cut processing method has an advantage that the processing can be performed in a short time, but also has a disadvantage that the smoothness of the processing surface is low.

On the other hand, the hot plate processing method is
It has an excellent feature that an end face with higher precision than the free cut processing method can be processed in a shorter time than the polishing processing method. The details of the conventional optical fiber end face processing method using this hot plate processing method will be described below with reference to the drawings, taking the connection of an optical cable to an F07 connector plug as an example.

[0005] As shown in FIG.
By stripping the jacket 2a of the optical cable 2 by a predetermined length (for example, about 7 mm) using
b is partially exposed. After inserting the optical fiber 2b into the insertion hole 3a formed in the F07 connector plug 3 by a predetermined length (for example, about 0.3 mm) from the tip of the ferrule 4, the optical fiber 2b is inserted. The stopper 5 is press-fitted into the stopper mounting portion 3b. By this press-fitting, the jacket 2a in the F07 connector plug 3 is sandwiched between the F07 connector plug 3 and the stopper 5, so that the optical cable 2 is fixed to the F07 connector plug 3 so as not to be pulled out.

[0008] The optical fiber 2 b of the optical cable 2 attached to the F07 connector plug 3 in this way is shown in FIG.
The end face processing is performed by the hot plate heater 6 shown in FIG. That is, the hot plate heater 6 is provided with a heating surface 6a, which is heated to, for example, about 160 ° C., and the optical fiber 2b is vertically moved for, for example, 5 seconds to 1 hour.
Press the F07 connector plug 3 together for 0 seconds.
FIG. 9 shows the optical fiber 2b before being pressed, which is in a state of protruding from the tip of the ferrule 4 by about 0.3 mm as described above. Note that the F07 connector plug 3 of the present description has a pair of ferrules 4. However, in FIGS. 9 and 10 described below, the optical fiber 2b in one ferrule 4 will be illustrated and the description will be continued.

As shown in FIG. 9, the ferrule 4 has a guide hole 4a which is a cylindrical space through which the optical fiber 2b is inserted, and a conical opening which expands from the lower end of the guide hole 4a toward the tip of the ferrule 4. Tapered hole 4 which is a trapezoidal space
b are formed. A gap 7 is formed between the tapered hole 4b and the optical fiber 2b, and the volume of the gap 7 is substantially equal to the volume of the protruding portion of the optical fiber 2b.

FIG. 10 shows the optical fiber 2b being pressed. As described above, since the volume of the gap space 7 is substantially equal to the volume of the protruding portion, the protruding portion is separated from the heating surface 6a. Due to the heat transfer, the gap space 7 is melted and deformed. The optical fiber 2 thus formed
The leading end portion b has a divergent shape that matches the shape of the tapered hole 4b, and the leading end surface 2c is formed flat by being in close contact with the smooth heating surface 6a.

After that, while the pressing state of FIG. 10 is maintained, the heating of the heating surface 6a is stopped so that the optical fiber 2b
Is cooled and solidified while maintaining the smooth tip surface 2c, and the end face processing is completed. The tapered hole 4b
Instead of having a counterbore 4c shown in FIG. 11, a counterbore 4c as shown in FIG. 11 has also been put to practical use. A hole 4c is provided.

[0010]

By the way, the conventional method for processing the end face of an optical fiber by the hot plate processing method described above has the following problems. That is, when the tip is melted to obtain a smooth tip surface 2c, in order to prevent the melted portion of the protruding portion from flowing between the tip surface of the ferrule 4 and the heating surface 6a to form burrs. , The ferrule 4 is provided with a tapered hole 4b and a counterbore 4c.
The distal end portion of the optical fiber 2b has an enlarged distal end shape as shown in FIGS.

When such an optical fiber 2b is used in an optical transmission path, the coupling loss increases due to the shape of the end portion. To reduce as much as possible
It is preferable that the dimension Δh of the ferrule 4 shown in FIGS. 10 and 11 be as small as possible, and more preferably the dimension Δh ≒ 0. However, this dimension △
In order to reduce h, the optical fiber 2
It is required to control the protruding length of the protruding portion of b to be extremely short. However, it is difficult to accurately control such minute dimensions. Sticking out on the surface,
Alternatively, if the protruding length is too short, there arises a problem that a smooth front end surface 2c cannot be formed due to insufficient close contact with the heating surface 6a.

In order to avoid such a problem, if an attempt is made to secure a certain size Δh, in addition to the problem of the coupling loss, the fused portion of the optical fiber 2b that has escaped to the gap space 7 will again have the axial center. The optical fiber 2b may return to concentrate, and the cladding may be mixed into the core of the optical fiber 2b, further impairing the optical transmission performance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and does not hinder the optical transmission performance in the processing of the end face of the optical fiber, and furthermore, as in the conventional case, the protrusion length of the tip of the optical fiber. It is an object of the present invention to provide an optical fiber end face processing method that does not need to control the length.

[0014]

Means for Solving the Problems A method for treating an end face of an optical fiber according to the present invention employs the following means in order to solve the above problems. That is, in the method for treating an end face of an optical fiber according to claim 1, the end face of the optical fiber is smoothed by using a smooth heating surface, and the optical fiber is formed in an optical fiber holding portion. A step of inserting into a guide hole which is a cylindrical space and holding vertically to the heating surface, and disposing a filler having the same refractive index as the core of the optical fiber between the end surface and the heating surface. And a step of pressing a peripheral edge formed at the distal end of the optical fiber holding portion on the heating surface side so as to make close contact with the heating surface, and welding the filler to the end surface. Features.

According to the method for treating an end face of an optical fiber according to the first aspect, first, an optical fiber is inserted and fixed in a guide hole, and a filler is provided between an end face of the optical fiber and a heating surface. To be positioned. Thereafter, the filler is pressed between the end surface of the optical fiber and the heating surface by pressing the peripheral edge of the guide hole toward the heating surface. The filler at this time is melted by the heat transfer from the heating surface, flows into and fills the concave and convex portions formed on the end face, and is smoothened by being deformed into a shape closely contacting the smooth heating surface. Molded into

According to a second aspect of the present invention, in the method for treating an end face of an optical fiber according to the first aspect, a ferrule is used as the optical fiber holding portion, and the guide hole is formed coaxially inside the ferrule. The ferrule is characterized in that a tapered surface tapering toward the peripheral edge of the distal end is formed on the outer peripheral portion of the distal end of the ferrule.

According to the method for treating an end face of an optical fiber according to the second aspect of the present invention, the tip end of the ferrule is formed into a tapered surface tapering toward the periphery of the tip, thereby providing a sharp tip end.

According to a third aspect of the present invention, there is provided a method of processing an end face of an optical fiber according to the first or second aspect, wherein the columnar body has a circular end face having an outer diameter substantially the same as the inner diameter of the guide hole. Wherein the circular end face is used as a heating surface.

According to the method for treating an end face of an optical fiber according to the third aspect, when the optical fiber is pressed, the peripheral edge of the circular end face and the distal end edge of the guide hole are made to coincide with each other so that the filler material is filled. Acts as a blade that cuts out the protruding part. Further, since the distal end surface of the ferrule does not abut against the heating surface, the filler is not pressed more than necessary and is not easily adhered to the distal end surface of the ferrule.

According to a fourth aspect of the present invention, in the method of treating an end face of an optical fiber according to any one of the first to third aspects, the filler is made of the same material as the core. And

According to the method for treating an end face of an optical fiber according to the fourth aspect of the present invention, the material of the filler is the same as that of the core of the optical fiber. The characteristics and the thermal characteristics such as the heat shrinkage become the same as the core of the optical fiber main body.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The method for treating an end face of an optical fiber according to the present invention is to flatten the end face of the optical fiber by pressing the end face against a smooth heating surface. However, it is needless to say that the present invention is not limited to these. In each of the embodiments, the case where an optical fiber is attached to the F07 connector plug will be described as an example.

First Embodiment First, a first embodiment will be described with reference to FIGS. The steps up to the step of stripping the jacket 2a of the optical cable 2 to partially expose the optical fiber 2b are the same as those described in the related art.

In the first embodiment, the optical fiber 10 is
Inserting a guide hole 12 which is a cylindrical space into a ferrule 13 (optical fiber holding portion) formed coaxially therein to hold the ferrule 13 perpendicularly to a heating surface 11 of a hot plate heater; Disposing a filler 14 having the same refractive index as that of the core of the optical fiber 10 between the end face 10a of the optical fiber 10 and the heating face 11; The front end edge 12a formed at the front end (facing end) is pressed against the heating surface 11 so as to be in close contact with the heating surface 11, and the filler 14 is welded to the end surface 10a. And a step of cutting off the protruding portion 14a of the filled filler 14 at the distal end edge 12a.

Further, in the first embodiment, the ferrule 1
3 is also different from the ferrule 4 described in the related art in that a tapered surface 15 tapering toward the distal end edge 12a is formed on the outer peripheral portion of the distal end. This tapered surface 1
5, when viewed in a cross section passing through the axis of the ferrule 13 (cross section shown in FIG. 1), the angle α formed between the ferrule 13 and a virtual plane perpendicular to the axis is determined by the difficulty of manufacturing the tip of the ferrule and the protrusion of the filler. It is appropriately set from the range of 0 ° <α <90 ° in consideration of the releasability of the part, the shape of the receptacle coupled with the ferrule, and the like. However, since the manufacture is easy, the range is 10 ° to 60 °. Preferably, there is.

The optical fiber 10 is first inserted coaxially into the guide hole 12, the end face 10a is brought as close as possible to the distal end edge 12a, and then the optical fiber 10 is covered by caulking or the like. (Not shown) to the F07 connector plug. After that, the ferrule 13 is held above the heating surface 11 so that the ferrule 13 and the guide hole 12 are perpendicular to the heating surface 11, and the filler 14 is filled between the end surface 10 a of the optical fiber 10 and the heating surface 11. By placing on the heating surface 11 so as to be located between them, the state before pressing shown in FIG. 1 is obtained.

The filler 14 used here has a bead shape, and is made of a material such as the optical fiber 1.
It is preferable that the core has the same optical characteristics (having the same refractive index as at least) and the same thermal characteristics (having the same thermal shrinkage) as the core of No. 0, and is made of the same material as the core. Is more preferable.

Next, the ferrule 13 is lowered while maintaining the vertical state with respect to the heating surface 11, and the filler 14 is sandwiched between the distal end edge 12 a and the heating surface 11. The filling material 14 at this time is, for example, the heating surface 1 heated to about 160 ° C.
1, and flows into and fills the concave and convex portions formed on the end face 10a of the optical fiber 10, and the excess becomes between the tip peripheral edge 12a and the heating surface 11. Extruded part 1
4a.

When the pressing is further advanced, as shown in FIG. 2, the distal end edge 12a comes into close contact with the heating surface 11, the protruding portion 14a is cut off from the optical fiber 10 body, and the heating surface of the filler 14 is heated. The surface which is in contact with the surface 11 is in close contact with the smooth heating surface 11 and is smoothed.

At this time, even if the filler 14 filled in the guide hole 12 attempts to spread in the radial direction of the optical fiber 10, the filler 14 is restricted by the guide hole 12, so that the filler 14 may spread. I cannot do it. As a result, the distal end portion of the optical fiber 10 is formed into a right circular column shape in which the cross-sectional shape does not become wider and divergent as in the related art, and a constant outer diameter cross-section is maintained. Thereafter, the heating of the heating surface 11 is stopped while the pressing state of FIG. 2 is maintained, so that the filler material 14 is solidified by radiation cooling, is smooth, and has a flat surface with the peripheral edge 12a of the ferrule 13 as a peripheral edge. 16 are formed. At this time, the protruding portion 14a also solidifies at the same time.

Then, as shown in FIG.
By raising 3 above the heating surface 11, the protruding portion 14a is removed, and the mounting operation is completed. At this time, even if the protruding portion 14a adheres to the ferrule 13, the adhering force is not strong for a reason to be described later, so that it can be easily removed by air blowing or the like.
The F07 connector plug after the attachment is butt-connected to another optical fiber in a receptacle (not shown), light is transmitted through this connection portion, and the amount of light coming out of the other end is measured, so that the evaluation of the coupling loss can be performed. Done.

According to the method for treating the end face of an optical fiber according to the first embodiment, the filling material 14 having the same refractive index as the core of the optical fiber 10 is melted to fill the insufficient portion of the end face 10a of the optical fiber 10. In this case, the lacking portion is
, So that the optical transmission capability is not hindered, and it is not necessary to control the protruding length of the tip of the optical fiber 10 as in the conventional case.

Further, according to the method for treating the end face of the optical fiber of the first embodiment, the outer peripheral portion of the distal end of the ferrule 13 is formed into a tapered surface 15 having a tapered shape toward the distal end edge 12a. Thus, by contacting the distal end edge 12a and the heating surface 11, the excess protruding portion 14a that has protruded can be easily and reliably cut. Further, since the tapered surface 15 does not abut against the heating surface 11, it is possible to prevent the protruding portion 14a from being pressed more than necessary and sticking to the front end of the ferrule 13, and it is possible to blow air or the like. The protrusion 14a can be easily removed from the ferrule 13.

According to the method for treating the end face of the optical fiber of the first embodiment, the material of the filler 14 is
By using the same material as the core, the optical characteristics such as the refractive index of the portion filled with the filler 14 become the same as the core of the optical fiber 10, so that the optical transmission capability is not reduced. Furthermore, since the thermal characteristics such as the heat shrinkage of the portion filled with the filler 14 are the same as those of the core of the optical fiber 10, it is possible to prevent a problem such as peeling off from the end face 10a after cooling. .

Second Embodiment Next, a second embodiment of the present invention will be described below with reference to FIGS. In the second embodiment, the same components as those described in the first embodiment with reference to FIGS. 1 to 3 are denoted by the same reference numerals, and the description thereof will be omitted.

The second embodiment differs from the first embodiment in that a ferrule 13 has a hollow circular tip surface 20 instead of a tapered surface 15 at the tip portion.
Inner diameter dimension d1 of guide hole 12 (for example, 1 mm)
A cylindrical projection (columnar body) having an upper end surface of a circular heating surface 21a having an outer diameter d2 (for example, 1 mm) substantially the same as that of FIG.
21 and the sheet shape (for example, thickness 1).
(00 micrometer).

First, the optical fiber 10 is inserted into the guide hole 12, and the optical fiber 10 is fixed to the F07 connector plug by caulking or the like so that it cannot be pulled out. Thereafter, the ferrule 13 is held above the heating surface 11 so that the ferrule 10 and the guide hole 12 are perpendicular to the heating surface 21a, and the sheet-shaped filler 22 is filled with the end surface 10a of the optical fiber 10 and the heating surface. By placing it on the heating surface 21a so as to be located between the heating surface 21a and the heating surface 21a, the state before pressing shown in FIG. 4 is obtained.

As the material of the filler 22 used here, as in the first embodiment, the same optical characteristics (having at least the same refractive index) as the core of the optical fiber 10 and the same thermal characteristics (thermal shrinkage) are used. And the like are the same), and more preferably the same material as the core.

Next, the ferrule 13 is lowered, and the filler 22 is sandwiched between the tip peripheral edge 12a and the heating surface 21a. The filler 22 at this time is melted by heat transfer from the heating surface 21a heated to, for example, about 160 ° C., and flows into and fills concaves and convexes formed on the end surface 10a of the optical fiber 10 while filling the same. The extra ones are
It is pushed out to the outside from between the tip peripheral edge 12a and the heating surface 21a to form the protruding portion 22a. When the pressing is further advanced, the tip peripheral edge 12a and the peripheral edge 21b of the heating surface 21a coincide with each other, and by cutting off the protruding portion 22a as a blade, a pressing state shown in FIG. 5 is obtained.

At the time of this pressing, the filler 22 remaining in the guide hole 12 is restricted by the guide hole 12, so that it cannot spread in the radial direction. As a result, the distal end portion of the optical fiber 10 is formed into a right circular column shape in which the cross-sectional shape does not become wider and divergent as in the related art, and a constant outer diameter cross-section is maintained. Thereafter, while the pressing state of FIG. 5 is maintained, the heating of the heating surface 21a is stopped, so that the distal end portion of the optical fiber 10 is solidified by heat radiation cooling, is smooth, and the distal end surface 2 of the ferrule 13 is smoothed.
A flat surface 23 flush with 0 is formed.

Then, as shown in FIG.
By raising 3 above the heating surface 11, the protruding portion 22a is removed, and the mounting operation is completed. At this time, even if the protruding portion 22a adheres to the ferrule 13, the adhesive force is not strong for the same reason as described in the first embodiment, so that it is easy to spray air or the like. Removed. The F07 connector plug after the attachment is butt-connected to another optical fiber in a receptacle (not shown), light is transmitted through this connection portion, and the amount of light coming out of the other end is measured, so that the evaluation of the coupling loss can be performed. Done.

According to the second embodiment, the same effects as those of the first embodiment can be obtained. Further, according to the second embodiment, by matching the peripheral edge 21b of the heating surface 21a with the distal peripheral edge 12a of the guide hole 12, these serve as blades for cutting the protruding portion 22a of the filler 22. The protruding portion 22a can be easily and reliably removed. Further, since the distal end surface 20 of the ferrule 13 does not abut on the heating surface 21a, it is possible to prevent the protruding portion 22a from being pressed more than necessary and to prevent this from easily sticking to the distal end surface 20 of the ferrule 13,
The protruding portion 22a can be easily removed from the ferrule 13 by blowing air or the like.

In the method for treating the end face of an optical fiber according to the first and second embodiments, the case where the optical fiber 10 is attached to the F07 connector plug has been described as an example. However, the present invention is not limited to the F07 connector plug. Instead, the present invention may be applied to attachment to other types of optical connectors.

In the first and second embodiments, the ferrule 13 is used as the optical fiber holding portion, the hole in the ferrule 13 is used as the guide hole 12, and the ferrule 13 is fixed to the F07 connector plug after termination. However, the present invention is not limited to this, and a jig (not shown) having a guide hole 10 is prepared, and is used as an optical fiber holding unit instead of the ferrule 13. Similarly, the optical fiber 1 is inserted into the guide hole 12.
Alternatively, a two-stage type termination method may be adopted in which 0 is inserted and termination is performed, and after termination, it is pulled out from the guide hole 12 and inserted into an optical connector or the like and fixed.

In the first embodiment, the bead-shaped filler 14 is used. However, other shapes such as the sheet-shaped filler 22 may be used. Conversely, in the second embodiment, the sheet-shaped filler 22 is used, but other shapes such as a bead-shaped filler 14 may be used.

Although the heating surface 11 of the first embodiment is flat, the circular end surface of the cylindrical projection 21 may be employed as the heating surface 21a as shown in the second embodiment. On the other hand, in the second embodiment, the upper end surface of the cylindrical projection 21 is used as the heating surface 21a. However, the present invention is not limited to this, and the flat heating surface 1 as in the first embodiment is used.
1 may be used.

In the first embodiment, the ferrule 13 having the tapered surface 15 at the tip end is used. However, the present invention is not limited to this, and the ferrule 13 may have a hollow circular shape as shown in the second embodiment. The one having the flat tip surface 20 may be used. On the other hand, in the second embodiment, the ferrule 13 has a hollow circular flat distal end surface 20 at the distal end portion. However, the present invention is not limited thereto, and the ferrule 13 having the tapered surface 15 may be used. You may.

[0048]

According to the method for treating an end face of an optical fiber according to the first aspect of the present invention, a filling material having the same refractive index as that of the core of the optical fiber is melted to fill the insufficient portion of the end face of the optical fiber. Since the insufficiency is filled with the filler and formed into a smooth shape, there is no hindrance to the optical transmission capacity, and there is no need to adjust the protrusion length of the tip of the optical fiber as in the conventional case. It becomes possible.

According to the method for treating an end face of an optical fiber according to the second aspect, the tip end of the ferrule is formed into a tapered surface with a tapered shape so that a sharp tip end is formed. It is possible to easily and surely cut off the excess amount of the filler that has protruded from the space. Furthermore, since this tapered surface does not come into contact with the heating surface, it is possible to press the protruding filler more than necessary and prevent it from sticking to the tip of the ferrule. It is possible to remove the protruding portion of the filler.

According to the method for treating an end face of an optical fiber according to the third aspect, the circular end face of the columnar body is used as a heating face, and the periphery of the heating face and the tip end periphery of the guide hole are matched. Since these serve as blades for cutting the protruding portion of the filler, the protruding portion of the filler can be easily and reliably removed. Furthermore, since the tip of the ferrule does not come into contact with the heating surface, it is possible to press the protruding filler more than necessary and prevent it from sticking to the tip of the ferrule. , The protruding portion of the filler can be easily removed.

According to the method for treating an end face of an optical fiber according to the fourth aspect of the present invention, the material of the filler is the same as that of the core of the optical fiber. Since the optical characteristics are the same as those of the core of the optical fiber main body, the optical transmission capability is not reduced. Furthermore, since the thermal characteristics such as the heat shrinkage ratio in the portion filled with the filler are the same as those of the core of the optical fiber main body, it is also possible to prevent problems such as peeling off from the end surface of the optical fiber after cooling. .

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a step of a first embodiment of an optical fiber end face processing method of the present invention.

FIG. 2 is a side sectional view showing the next step of the optical fiber end face processing method.

FIG. 3 is a side sectional view showing a next step of the method for treating an end face of the optical fiber.

FIG. 4 is a side sectional view showing a process of Embodiment 2 of the method for treating an end face of an optical fiber of the present invention.

FIG. 5 is a side sectional view showing the next step of the optical fiber end face processing method.

FIG. 6 is a side sectional view showing a next step of the optical fiber end face processing method.

FIG. 7 is a perspective view showing a step of a conventional optical fiber end face processing method.

FIG. 8 is a perspective view showing a next step of the optical fiber end face processing method.

FIG. 9 is a side sectional view showing the next step of the optical fiber end face processing method.

FIG. 10 is a side sectional view showing a next step of the optical fiber end face processing method.

FIG. 11 is a side sectional view showing a modification of the optical fiber end face processing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Optical fiber 10a ... End surface 11 ... Heating surface 12 ... Guide hole 14, 22 ... Filler 12a ... Front end periphery 13 ... Ferrule, optical fiber holding part 15 ...・ Tapered surface d1 ... Inner diameter d2 ... Outer diameter 21a ... Circular end surface (heating surface) 21 ... Cylindrical projection (columnar body)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayuki Sugiura 4-2-1 Ushikawa-dori, Toyohashi-shi, Aichi F-term (reference) 2H036 KA03 QA14 QA21 2H050 AA13 AB43Z AB47Z AC87 AC90

Claims (4)

[Claims] 1. A method for treating an end face of an optical fiber, wherein the end face of the optical fiber is smoothed using a smooth heating surface, wherein the optical fiber is placed in a guide hole which is a cylindrical space formed in an optical fiber holding portion. A step of inserting and holding vertically to the heating surface; a step of disposing a filler having the same refractive index as the core of the optical fiber between the end surface and the heating surface; Pressing the periphery of the tip formed at the tip on the heating surface side so as to be in close contact with the heating surface, and welding the filler to the end surface. . 2. The method for treating an end face of an optical fiber according to claim 1, wherein a ferrule is used as the optical fiber holding portion, the guide hole is formed coaxially inside the ferrule, and an outer peripheral portion of a tip of the ferrule is formed. Is a method of treating an end face of an optical fiber, wherein a tapered surface that tapers toward the distal end edge is formed. 3. The method for processing an end face of an optical fiber according to claim 1, wherein the circular end face of a columnar body having a circular end face having an outer diameter substantially the same as the inner diameter of the guide hole is used as a heating surface. A method for treating an end face of an optical fiber. 4. The method for treating an end face of an optical fiber according to claim 1, wherein the filler is made of the same material as the core.