JP2000304943A - End surface processing method for optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an end surface processing method for optical fiber which can reduce a coupling loss when the end surface of a plastic-made optical fiber is processed. SOLUTION: In the end surface processing method for optical fiber which makes an end surface 2d of an optical fiber 2b smooth by pressing it against a smooth heating surface 6a, such end surface processing method is adopted that presses the optical fiber 2b by forming a guide hole 10 as a columnar space, where the optical fiber 2b can be inserted, perpendicularly on the heating surface 6a and then inserting the optical fiber 2b into the guide hole 10.

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 coating a core material made of a fiber such as methacrylic resin with a fluorinated methacrylic resin having a lower refractive index than the core material. It is used for optical transmission applications such as guides. When this kind of optical fiber is applied to optical communication or the like, it is required to treat the end face as smooth as possible. That is, if the finish of the end face is rough, it causes a coupling loss to increase. Therefore, it is necessary to finish the end face smoothly in order to suppress the loss as much as possible.

[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.

The optical fiber 2b of the optical cable 2 thus attached to the F07 connector plug 3
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 together with the F07 connector plug 3 for 0 seconds.
FIG. 8 shows the optical fiber 2b before pressing, and as described above, the optical fiber 2b projects from the tip of the ferrule 4 by about 0.3 mm. Note that the F07 connector plug 3 of the present description has a pair of ferrules 4. However, in FIGS. 8 and 9 described below, the optical fiber 2b in one ferrule 4 will be illustrated and the description will be continued.

As shown in FIG. 8, 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. 9 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 transmitted from the heating surface 6a. Due to the heat, it is melted and deformed so as to fill the gap space 7. 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. Thereafter, the heating of the heating surface 6a is stopped while the pressing state of FIG. 9 is maintained, so that the distal end portion of the optical fiber 2b is cooled and solidified while maintaining the smooth distal end surface 2c, and the end surface processing is completed. I do.

[0009]

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. In other words, when the tip is melted to obtain a smooth tip surface 2c, the molten resin forming the protruding portion flows between the tip surface of the ferrule 4 and the heating surface 6a to form burrs. In order to avoid this, the tapered hole 4b is provided in the ferrule 4, but as a result, the distal end portion of the optical fiber 2b has a divergent shape as shown in FIG. If the F07 connector plug 3 having the optical fiber 2b terminated in such a shape is used, for example, on the light transmission side in an optical transmission path, the light transmission cross-sectional area at the divergent portion is enlarged. Most of the light incident on portions other than the portion corresponding to the end face of the optical fiber before the processing is lost without being introduced into the optical fiber 2b. On the other hand, the light receiving element (not shown) on the light receiving side can receive only light corresponding to the end face of the optical fiber before the end face processing, and the other light is lost. That is, when the end face processing is performed by this method, a problem occurs that the coupling loss increases on the light transmitting side and the light receiving side.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for processing an end face of an optical fiber which can reduce coupling loss in the end face processing of the optical fiber.

[0011]

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 pressing the end face of the optical fiber against a smooth heating surface. The method is characterized in that a guide hole is formed, which is a cylindrical space into which the optical fiber can be inserted and which can be inserted vertically, and then the optical fiber is inserted into the guide hole.

According to the method for treating an end face of an optical fiber according to the first aspect, first, a guide hole which is a cylindrical space is formed on a heating surface. Thereafter, the optical fiber is inserted while being guided by the guide hole, and the tip portion is pressed against the heating surface. Then, the tip portion of the optical fiber is melted by the heat transfer from the heating surface, and is deformed into a shape conforming to the smooth heating surface, thereby being formed flat. That is, irregularities are formed on the distal end surface of the optical fiber before molding, but when the optical fiber comes into contact with the heating surface and is heated, the convexities melt and flow into the concaves. It is made. At this time, the heating surface side guide hole exit and the heating surface are in close contact with each other, and the optical fiber does not protrude from the guide hole during the end face processing, so that the melted material does not remain on the end face of the optical fiber as burrs or the like. The tip of the optical fiber terminated in this way has a straight cylindrical shape that matches the guide hole that is a cylindrical space, and the light transmission path is not a divergent shape as in the past, but a straight. Shape.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method for treating an end face of an optical fiber according to the present invention is to press an end face of the optical fiber against a smooth heating surface to smooth the end face.
However, the present invention is not limited to these. In addition,
Also in the present embodiment, a case where an optical fiber is attached to an F07 connector plug will be described as an example.
3 to 3, the same components as those described in the related art are denoted by the same reference numerals, and description thereof will be omitted.

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 prior art. In the present embodiment, the pressing of the optical fiber 2b is performed with the heating surface 6a.
The optical fiber 2
The difference is that the optical fiber 2b is inserted into the guide hole 10 after forming the guide hole 10 which is a cylindrical space through which b can be inserted. In the present invention, the optical fiber 2b
A plastic material is preferably used.
The distribution or structure of the optical fiber 2b such as the refractive index is not particularly limited, and a known one is used.

That is, before passing the optical fiber 2b, the front end surface 11a of the ferrule 11 of the F07 connector plug, in which the guide hole 10 is formed coaxially, is heated to the heating surface 6a.
Press tightly to fix it. At this time, the ferrule 11 and the guide hole 10 are so arranged that the heating surface 6a and the tip end surface 11a are in close contact with each other without any gap.
Is perpendicular to the heating surface 6a. Then, by inserting the optical fiber 2b into the guide hole 10 in this state, the state shown in FIG. 1 is obtained. The ferrule 11 is made of a material that is not deformed by the heat of the heating surface 6a, such as various heat-resistant resins and metals.

When the optical fiber 2b is further inserted from the state shown in FIG. 1, as shown in FIG.
d comes in direct contact with the heating surface 6a heated to, for example, about 160 ° C., and is heated by heat transfer from the heating surface 6a to perform the end surface treatment. The heating temperature is appropriately set in consideration of the material constituting the optical fiber 2b and the like. That is, the end face 2d before the contact (before heating) has a large number of irregularities, but during the contact (during heating), as shown in FIG. As a result, it flows into the concave portion 12b, and finally, the unevenness is made uniform and the shape is smoothened. At this time, even if the molten convex portion 12a tries to spread in the radial direction of the optical fiber 2b, the guide hole 1
Because it is regulated by 0, it cannot be spread. As a result, the distal end portion of the optical fiber 2b is formed into a right circular column shape in which the cross-sectional shape does not become widened and the constant outer diameter cross-section is maintained as in the related art.

Thereafter, the heating of the heating surface 6a is stopped while maintaining the pressing state of FIG.
Is solidified by heat radiation cooling to form a flat surface 13 which is smooth and flush with the distal end surface 11a of the ferrule 11. Then, by fixing a jacket (not shown) covering the optical fiber 2b to the F07 connector plug so as not to be pulled out by caulking or the like, the mounting operation is completed.
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 an end face of an optical fiber of the present embodiment, after forming a guide hole 10 which is a vertical cylindrical space on the heating surface 6a, the optical fiber 2b is inserted into the guide hole 10; The optical fiber 2b is pressed against the heating surface 6a to form the optical fiber 2b.
Has a cylindrical shape that matches the guide hole 10, and the light transmission path does not become divergent, so that the coupling loss can be reduced.

In the method of treating an end face of an optical fiber according to the above embodiment, the case where the optical fiber 2b 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, and other types of optical connectors may be used. It may be applied to attachment to a device. Further, in the above embodiment, the hole in the ferrule 11 is used as the guide hole 10 and is fixed to the F07 connector plug as it is after termination. However, the present invention is not limited to this, and a jig (not shown) having the guide hole 10 is used. After pressing the guide hole 10 so that the guide hole 10 is perpendicular to the heating surface 6a, the optical fiber 2b is inserted into the guide hole 10 and terminated as in the above-described embodiment,
After the termination, a two-stage termination method may be adopted in which the guide hole 10 is pulled out from the inside of the guide hole 10 and inserted into an optical connector or the like and fixed.

[Example] A comparison test was performed on the coupling loss between the optical fiber obtained by the above-described conventional end face processing method and the optical fiber obtained by the above-described end face processing method. In this test, the optical fiber 1 terminated to the optical connector plug 15 by the conventional end face processing method shown in FIG.
6 and the optical connector plug 1 according to the end face processing method of the present embodiment.
7 was compared with the optical fiber 18 terminated. The optical fiber 16 and the optical fiber 18 each had a wire diameter of about 1 mm, and the divergent portion 19 of the optical fiber 16 had a dimension of about 0.3 mm in the axial direction and about 0.3 mm in the radial direction.

As shown in FIG. 5, the optical fiber 16 having both ends terminated as described above is connected to a transmission device 20 for transmitting light of a constant intensity, and an optical power meter 21 for receiving and measuring the light intensity. And the coupling loss was measured.
Next, the optical fiber 16 was replaced with the optical fiber 18, and the same test was performed to measure the coupling loss.

In this comparative test, the transmitting device 20
HFBR552 manufactured by Hewlett-Packard Company
7, an AQ1135 manufactured by Ando Electric Co., Ltd. was used as the optical power meter 21, an F07 connector plug was used as the optical connector plug 15 and the optical connector plug 17, and the optical fiber 16 and the optical fiber 18 before termination were used. EHV4002 manufactured by Mitsubishi Rayon Co., Ltd. was used. When the difference in the coupling loss between the optical fiber of the example and the optical fiber of the comparative example was determined, the coupling loss of the optical fiber 18 was reduced by about 1.74 dB as compared with the optical fiber 16.

[0023]

According to the method for treating an end face of an optical fiber according to the first aspect of the present invention, after a guide hole which is a vertical cylindrical space is formed on a heating surface, an optical fiber is inserted into the guide hole. By pressing the optical fiber against the heating surface and molding it, the optical fiber after termination has a cylindrical shape that matches the guide hole, and the light transmission path does not become divergent, reducing coupling loss. It is possible to do.

[Brief description of the drawings]

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

FIG. 2 is a side sectional view showing the same end face processing method.

FIG. 3 is a view showing the same end face processing method,
It is an enlarged view of a part.

FIG. 4 is a side sectional view showing optical fibers used in a comparative test for determining a difference in coupling loss between an optical fiber obtained by the same end face processing method and an optical fiber obtained by a conventional processing method.

FIG. 5 is a diagram showing a schematic device configuration of the comparative test, and is a connection diagram.

FIG. 6 is a perspective view showing a part of steps of a conventional method for treating an end face of an optical fiber.

FIG. 7 is a perspective view showing the next step of the end face processing method.

FIG. 8 is a side sectional view showing a next step of the end face processing method.

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

[Explanation of symbols]

 2b: Optical fiber 2d: End surface 6a: Heating surface 10: Guide hole

Claims (1)

[Claims] 1. A method for treating an end face of an optical fiber, wherein the end face of the optical fiber is pressed against a smooth heating surface to smooth the surface, wherein the pressing of the optical fiber rises perpendicularly to the heating surface, and An end face processing method for an optical fiber, comprising: forming a guide hole which is a cylindrical space through which an optical fiber can be inserted, and inserting the optical fiber into the guide hole.