JP2003176150A - Method of manufacturing optical fiber having core bulge part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten high temperature treatment time required for forming a core bulge part. <P>SOLUTION: A pair of microburners 1a, 1b are arranged adjacent to each other and brought close to a optical fiber F, and thereafter the microburners 1a, 1b are moved in the opposite direction of the optical axis of the optical fiber. Accordingly, each microburner shares a half part from the center of the core bulge part Ce. Thereby, the moving distance of each microburner 1a, 1b becomes half of that in the case when one microburner is used. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical fiber having a core bulge portion, and more specifically, a core bulge portion capable of shortening a high temperature treatment time for forming the core bulge portion. The present invention relates to a method for manufacturing an optical fiber.

[0002]

2. Description of the Related Art FIG. 8 is a sectional view showing a method for enlarging a mode field diameter of an optical fiber disclosed in Japanese Patent No. 2693649. A pair of micro-burners 1a and 1a ′ are opposed to each other with the optical fiber strand F sandwiched therebetween (or micro burners are opposed to each other with each optical fiber strand sandwiched between each pair of a plurality of pairs of micro burners), By moving the microburners 1a and 1a 'along the optical axis direction of 1, the intermediate portion of the optical fiber element wire F is subjected to high temperature treatment to expand the core diameter and form the core bulge portion.

[0003]

In the conventional method for expanding the mode field diameter of an optical fiber, the micro burners 1a and 1a 'are heated while heating the same portion of the optical fiber F with a pair of micro burners 1a and 1a'. By moving along the optical axis direction of the strand F (or by moving the microburner along the optical axis direction of the optical fiber strand while heating the same portion of the optical fiber with a plurality of pairs of microburners) , The core bulging portion is formed. However, even if a plurality of microburners are used, since the same portion of the optical fiber F is heated, the distance traveled by the microburners is the same as when one microburner is used, and the processing time at this point is shortened. No effect was obtained. Therefore, an object of the present invention is to provide a method of manufacturing an optical fiber having a core bulging portion, which can shorten the processing time by making it possible to shorten the moving distance of the microburner to form the core bulging portion. To provide.

[0004]

According to a first aspect of the present invention, in the present invention, a pair of heating means are closely arranged to approach an optical fiber strand, and then are separated along the optical axis direction of the optical fiber strand. Manufacture of an optical fiber having a core bulging portion characterized by forming a core bulging portion by moving each heating means in a direction to perform high temperature treatment on an intermediate portion of the optical fiber strand to expand the core diameter. Provide a way. In the method for manufacturing an optical fiber having a core bulging portion according to the first aspect, a pair of heating means is used, and each heating means is divided into halves from the center of the core bulging portion, so that each heating and unloading step is performed. The moving distance is half that in the case of using one heating means. Thereby, the processing time can be shortened. Then, a pair of heating means are closely arranged to approach the optical fiber strand, and then each heating means is moved along the optical axis direction of the optical fiber strand and in a direction away from each other so that the center of the core bulge portion is expanded. It is possible to form the core bulging portion having a shape in which the core diameter is widest and the core diameter smoothly returns to the original core diameter at both ends of the core bulging portion. After moving each heating means in the separating direction, each heating means may be separated from the optical fiber strand at both ends of the core bulging portion, or the moving direction may be reversed at both ends of the core bulging portion to both heating. The means may be moved away from the optical fiber strand at a place where the means are closely arranged in the center of the core bulging portion. In addition, after reversing the direction of movement along the optical axis of the optical fiber element several times, each heating means is attached to both ends of the core bulge or at the center of the core bulge. You can keep it away from the line.

According to a second aspect of the present invention, in the present invention, a pair of heating means are arranged so as to be spaced apart from each other and brought close to the optical fiber strand, and then each heating means is provided along and along the optical axis direction of the optical fiber strand. Provided is a method for manufacturing an optical fiber having a core bulging part, characterized in that the core bulging part is formed by moving a middle part of the optical fiber strand at a high temperature by moving the core to expand the core diameter. In the method of manufacturing an optical fiber having a core bulge portion according to the second aspect, a pair of heating means is used,
By dividing each of the heating bulges from the center of the core bulging portion by half, the moving distance of each heating bulge is halved as compared with the case of using one heating means. Thereby, the processing time can be shortened. Then, a pair of heating means are arranged side by side so as to be close to the optical fiber strand, and then each heating means is moved along the optical axis direction of the optical fiber strand and in a direction close to each other so that the center of the core bulge portion is formed. It is possible to form the core bulging portion having a shape in which the core diameter is widest and the core diameter smoothly returns to the original core diameter at both ends of the core bulging portion. After moving the heating means in the direction of approaching each other, both heating means may be moved away from the optical fiber strand at the center of the core bulging portion, or the moving direction may be reversed at the center of the core bulging portion for each heating. The means may be located at both ends of the bulging portion of the core and may be separated from the optical fiber strand.
Also, after reversing the direction of movement along the optical axis direction of the optical fiber strand several times, at both ends of the core bulging portion, or
Each heating means may be separated from the optical fiber strand at the center of the core bulging portion.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in more detail with reference to the embodiments shown in the drawings. The present invention is not limited to this.

1 to 4 are explanatory views showing a method of manufacturing an optical fiber having a core bulging portion according to an embodiment of the present invention. Note that the dimensional ratio is exaggerated for convenience of illustration.

First, as shown in FIG. 1, a pair of microburners 1a and 1b arranged close to each other is brought close to an intermediate portion of an optical fiber strand F composed of a core C and a clad L. As a result, as shown in FIG.
High temperature treatment is applied to the middle part of the core, and the core diameter expands. The microburners 1a and 1b burn, for example, acetylene gas or a mixed gas of propane gas and oxygen.

Next, as shown in FIG. 3, the microburners 1a and 1b are moved along the optical axis direction of the optical fiber strand F and in a direction away from each other. As a result, the portion where the core diameter is widened extends to form the core bulge portion Ce.

Finally, as shown in FIG. 4, the core bulge C
At both ends of e, the microburners 1a and 1b are separated from the optical fiber strand F. And the micro burners 1a and 1b
, The microburners 1a and 1b return to the positions shown in FIG.

The following changes may be made. (1) The moving direction may be reversed at both ends of the core bulging portion Ce, and the micro-burners 1a and 1b may be moved away from the optical fiber strand F at a place where the micro burners 1a and 1b are closely arranged at the center of the core bulging portion Ce.
That is, the positions of both microburners 1a and 1b may be moved so as to change in the order of FIG. 1, FIG. 2, FIG. 3, FIG. (2) The moving direction is reversed at both ends of the core bulging portion Ce, and the moving direction is reversed again when the micro-burners 1a and 1b are closely aligned at the center of the core bulging portion Ce. After reversing the direction of movement of F along the optical axis direction several times, at both ends of the core bulging portion Ce or the core bulging portion Ce.
The micro burners 1a and 1b may be separated from the optical fiber strand F at the center of. For example, both micro burners 1
The positions of a and 1b may be moved so as to change in the order of FIGS. 1, 2, 3, 2, 3, 1, 2, and 4. (3) Both microburners 1a and 1b may be moved in the opposite direction to the above. That is, both micro burners 1a,
You may move so that the position of 1b may change in order of FIG. 4, FIG. 3, FIG. 2, and FIG. In addition, both micro burners 1a,
You may move so that the position of 1b may change in order of FIG. 4, FIG. 3, FIG. 2, FIG. 3, FIG. (4) A heater may be used as the micro burners 1a and 1b.

FIG. 5 is a sectional view of an optical fiber having a core bulge manufactured by the above manufacturing method. In the core bulging portion Ce, the core Ca smoothly expands in diameter, and after the portion Cc of the maximum core diameter ± 10% of the maximum core diameter continues, the core C
b has returned to the original diameter smoothly. The maximum core diameter D of the core bulging portion Ce is 12 μm to 50 μm. The lengths Sa and Sb from the end of the core bulge portion Ce to the position where the maximum core diameter minus 10% of the maximum core diameter are Sa and Sb are 0.5 mm to 3 m.
It is within the range of m, for example, 2 mm. Maximum core diameter ± 10% of maximum core diameter Length Cc is 1 m
It is in the range of m to 40 mm, for example, 2 mm.
The diameter φ of the clad L of the original optical fiber strand F is 1
25 μm and the core diameter d is about 10 μm.

FIG. 6 is a perspective view showing an embodiment in which a plurality of optical fiber strands F are simultaneously subjected to high temperature treatment.

FIG. 7 is a perspective view showing an embodiment in which the above-mentioned prior art and the present invention are combined. A pair of microburners 1a ′, 1b ′ facing the pair of microburners 1a, 1b with the optical fiber strand F interposed therebetween are provided, and one place is heated by the microburners 1a, 1a ′. 'To heat another place. And
The microburners 1a and 1a ′ and the microburners 1b and 1b are arranged along the optical axis of the optical fiber strand F and in opposite directions.
1b 'and move.

The manufactured optical fiber having the core bulge is cut by an optical fiber cutter at the center or substantially the center of the portion Cc within the range of the maximum core diameter ± 10% of the maximum core diameter. Then, a ferrule is attached to the end portion of the optical fiber after cutting, and the optical fiber and the end surface of the ferrule are polished to obtain an optical fiber assembly. In such an optical fiber assembly, since the hardness of the optical fiber and the scratches at the time of cutting vary, the polishing amount of the tip surface varies, but the cutting position of the optical fiber is the maximum core of the core bulging portion Ce. Since the diameter of the portion Cc is within the range of ± 10% of the maximum core diameter or the center thereof, the core diameter of the tip surface of the optical fiber after polishing is within the range of maximum core diameter ± 10% of the maximum core diameter. Less variation. Therefore, stable light characteristics can be obtained.
Then, since sufficient polishing allowance remains on both of the two optical fibers after cutting, two optical fibers used for the optical fiber assembly can be obtained by one cutting.

[0016]

According to the method of manufacturing the optical fiber having the core bulging portion of the present invention, the high temperature treatment time for forming the core bulging portion can be shortened.

[Brief description of drawings]

FIG. 1 is an illustration showing starting positions of a pair of microburners in an embodiment of the present invention.

FIG. 2 is an illustration showing the proximity positions of a pair of microburners in an embodiment of the present invention.

FIG. 3 is an illustration showing the separated positions of a pair of microburners in an embodiment of the present invention.

FIG. 4 is an illustration showing end positions of a pair of microburners in an embodiment of the present invention.

FIG. 5 is a cross-sectional view of an optical fiber manufactured according to an embodiment of the present invention.

FIG. 6 is a perspective view showing another embodiment of the present invention.

FIG. 7 is a perspective view showing still another embodiment of the present invention.

FIG. 8 is a perspective view showing a conventional manufacturing method.

[Explanation of symbols]

1a, 1b, 1a ', 1b' micro burner C, Ca, Cb, Cc core Ce core bulge L clad F Optical fiber strand

Continued front page    (72) Inventor Ma Ying             Ueda City, Nagano 300 Oya, Tokyo Special             Ueda Factory of Electric Wire Co., Ltd. F-term (reference) 2H050 AC83

Claims (2)

[Claims] 1. An optical fiber strand by arranging a pair of heating means in close proximity to each other to bring them closer to an optical fiber strand, and then moving each heating means along the optical axis direction of the optical fiber strand and in a direction away from each other. 2. A method of manufacturing an optical fiber having a core bulging part, characterized in that a core bulging part is formed by subjecting a middle part of the core to high temperature treatment to expand the core diameter. 2. An optical fiber strand by arranging a pair of heating means apart from each other to bring them closer to the optical fiber strand, and then moving each heating means along and along the optical axis direction of the optical fiber strand. 2. A method of manufacturing an optical fiber having a core bulging part, characterized in that a core bulging part is formed by subjecting a middle part of the core to high temperature treatment to expand the core diameter.