JP2001083359A - Welding and drawing device for optical fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a welding and drawing device for an optical fiber for manufacturing an optical fiber coupler having excellent polarization crosstalk characteristics with a high yield. SOLUTION: In a welding and drawing device for an optical fiber which is provided with a pressing jig 4 for pressing the optical fiber 1, a heating burner for heating and welding the optical fiber 1 pressed by the pressing jig 4 and a drawing device for drawing the optical fiber 1 heated and welded by the heating burner, the pressing jig 4 is composed so as to move left and right.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber fusion drawing apparatus, and more particularly to an optical fiber fusion drawing apparatus for manufacturing an optical fiber coupler using an elliptical core type polarization maintaining optical fiber.

[0002]

2. Description of the Related Art An optical fiber coupler using an elliptical core type polarization maintaining optical fiber is an important device in the field of optical measurement because it can branch signal light while preserving the polarization plane of the signal light. An apparatus for manufacturing this optical fiber coupler is an optical fiber fusion drawing apparatus. The polarization plane is
Considering a state in which light is an electromagnetic wave and time travels along the horizontal axis, an electric field and a magnetic field travel in a state where they are orthogonal to each other. The plane containing the electric field is called a polarization plane, and can be divided into linearly polarized waves whose planes do not change with time and circularly polarized waves whose planes rotate every moment. The plane of polarization considered in this patent is linearly polarized.

[0003] The optical fiber fusion drawing apparatus comprises a holding jig for holding down the optical fiber, a heating burner for heating / fusing the optical fiber held by the holding jig, and a heating / fusion for the heating burner. A stretching device for stretching the optical fiber (a device for stretching the optical fiber while holding it down at several places).

FIG. 3 is a view showing a manufacturing process of an optical fiber coupler in relation to a conventional optical fiber fusion drawing apparatus. The process numbers, work contents, and schematic diagrams are shown. An AA ′ cross-sectional view of the schematic diagram is shown at the right end. 11 is an optical fiber, 12 is an elliptical core portion, 13 is a clad portion, 14 is a left and right holding jig, 15 is a vertical holding jig, and 16 is a heating burner.

The optical fiber 11 is an elliptical core type polarization maintaining optical fiber, and comprises an elliptical core 12 and a cladding 13. The major axis and the minor axis of the elliptical core 12 are the eigen axes, and the linearly polarized light incident on the major axis and the minor axis is preserved even after being branched by the optical fiber coupler.

Hereinafter, a method of manufacturing an optical fiber coupler will be described for each process number.

[0007] 1. Axis alignment process Two optical fibers 11 having a length of several meters are prepared, and the coating on the central part of each is removed, and the clad portion 13 is exposed. Then, the two optical fibers 11 exposing the clad portion 13 are arranged. At this time, it is important to rotate and adjust each optical fiber 11 so that the directions of the elliptical core portions 12 are completely matched, that is, the major axes of the elliptical core portions 12 are parallel to each other. This adjustment is called adjustment of the eigenaxis. If the proper axis adjustment is not performed correctly,
The linearly polarized wave incident on the long axis (short axis) of the elliptical core 12 is
Since the short axis (long axis) component is generated in the counterpart elliptical core section 12, the polarization crosstalk characteristic is extremely deteriorated.

The polarization crosstalk characteristics are as described below. It is assumed that linearly polarized light enters one optical fiber 11 at the input end of the optical fiber coupler. The linearly polarized light is incident on the major axis side of the elliptical core 12. When the power of light polarized on the long axis side of the elliptical core 12 at the output end of the optical fiber coupler is Px, and the power of light polarized on the short axis of the elliptical core 12 is Py, η = 10・ Log (P
x / Py) is called a polarization crosstalk characteristic. Therefore, the smaller Py is, the larger η is, and the better the polarization crosstalk characteristic is.

[0009] 2. Left and Right Holding Step The left and right holding jigs 14 hold two locations of the two optical fibers 11 for which the adjustment of the unique axis has been completed.

[0010] 3. 1. Vertical holding process Then, two locations are pressed by the vertical holding jig 15 from above and below.

4. Heating / Melting / Stretching Step The clad portion 13 from which the coating has been removed is heated and fused by a heating burner 16. Then, stretching (stretching) is performed in the direction indicated by the arrow.

5. Stretching amount adjusting step The stretching amount is adjusted so that the optical power from the two output terminals of the optical fiber coupler becomes equal or a desired ratio is obtained. Remove the heating burner when the light power is equal or at the desired ratio. Then, a protective layer or the like is applied to the exposed portion of the clad to complete the optical fiber coupler.

[0013]

The conventional optical fiber fusion drawing apparatus has the following problems.

FIGS. 4A and 4B relate to a conventional optical fiber fusing and stretching apparatus, and are explanatory diagrams before the left and right holding jig 14 presses the optical fiber 11 and FIG. 4B after the optical fiber 11 is pressed. It is. The left and right holding jig 14 is of a type that rotates around a fulcrum. When the optical fiber 11 is held down, the main body of the left and right holding jig 14 comes into contact with the optical fiber 11 from right beside, and the optical fiber 11 is rotated. Therefore, even if the proper axis is properly adjusted in the axis alignment process, the optical fiber 11 rotates when pressed by the right and left holding jigs 14, and as a result, the optical fiber coupler having a good polarization crosstalk characteristic. The yield of manufacturing was getting worse.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the problems of the prior art and to provide an optical fiber fusion drawing apparatus for manufacturing an optical fiber coupler having good polarization crosstalk characteristics with a high yield.

[0016]

According to the present invention, there is provided a holding jig for holding an optical fiber, a heating burner for heating and fusing the optical fiber held by the holding jig. A stretching device for stretching the optical fiber heated and fused by the heating burner, wherein the holding jig is configured to move left and right.

The moving distance of the holding jig is controlled by a stopper.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 relates to a first embodiment of the optical fiber fusion drawing apparatus according to the present invention, and is an explanatory view (a) before the pressing jig presses the optical fiber and an explanatory view after pressing the optical fiber ( b). 1 is an optical fiber, 2 is an elliptical core part, 3 is a clad part, and 4 is a holding jig.

Since the holding jig 4 comes into contact with the optical fiber 1 from just beside and pushes out the optical fiber 1 as it is, the optical fiber 1
Can be aligned without rotating them. The frictional force between the optical fiber 1 and the table or stage on which the optical fiber 1 is installed is configured to be small. If the frictional force is large, the optical fiber 1 rotates when the optical fiber 1 is pushed out. By using such a structure, it is possible to hold down (align) the optical fiber 1 whose characteristic axis has been adjusted without rotating it.

FIGS. 2A and 2B relate to a second embodiment of the optical fiber fusion drawing apparatus according to the present invention. FIG. 2A is an explanatory view before the right and left holding jig presses the optical fiber and FIG. (B). 5 is an optical fiber, 6 is an elliptical core, 7
Denotes a clad portion, 8 denotes a right and left holding jig, and 9 denotes a stopper.

By moving the right and left holding jigs 8 from both sides of the optical fiber 5 by the same distance, the tension of the optical fiber 5 can be evenly applied. The moving distance of the left and right holding jigs 8 is configured to be adjustable by the thickness of the stopper 9.
Also in this case, the frictional force between the optical fiber 5 and the table or stage on which the optical fiber 5 is installed is configured to be small. If the frictional force is large, the optical fiber 5 rotates when the optical fiber 5 is pushed out. By using such a structure, it is possible to hold down (align) the optical fiber 5 whose characteristic axis has been adjusted without rotating it.

As a result of the use of the optical fiber fusion stretching apparatus described above, the rotation of the optical fiber which occurred during the holding step after the adjustment of the intrinsic axis of the optical fiber is completely eliminated, and the optical fiber having good polarization crosstalk characteristics is obtained. The fiber coupler could be manufactured with good yield. In the first and second embodiments, the elliptical core type polarization maintaining optical fiber has been described as the polarization maintaining optical fiber. However, the present invention can be similarly applied to the elliptical jacket type polarization maintaining optical fiber.

[0024]

According to the optical fiber fusion drawing apparatus of the present invention, a holding jig for holding an optical fiber, a heating burner for heating and fusing the optical fiber held by the holding jig, A stretching device for stretching the optical fiber heated and fused by a burner, wherein the holding jig has a structure moving left and right, so that polarization crosstalk characteristics can be improved. It has become possible to manufacture optical fiber couplers with excellent yield with good yield.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram (a) before a holding jig presses an optical fiber and an explanatory diagram (b) after pressing an optical fiber according to a first embodiment of an optical fiber fusion drawing apparatus of the present invention. is there.

FIGS. 2A and 2B are explanatory views showing a state before and after an optical fiber is pressed by a left and right holding jig according to a second embodiment of the optical fiber fusion drawing apparatus of the present invention, and FIGS. It is.

FIG. 3 is a view showing a manufacturing process of an optical fiber coupler according to a conventional optical fiber fusion drawing apparatus.

FIG. 4 is an explanatory view (a) before and after an optical fiber is pressed by a left and right holding jig, and an explanatory view (b) after the optical fiber is pressed, in a conventional optical fiber fusion drawing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical fiber 2 Elliptical core part 3 Cladding part 4 Holding jig 5 Optical fiber 6 Elliptical core part 7 Cladding part 8 Right and left holding jig 9 Stopper 11 Optical fiber 12 Elliptical core 13 Cladding part 14 Left and right holding jig 15 Vertical holding jig Tool 16 heating burner

Claims (2)

[Claims] 1. A holding jig for holding an optical fiber, a heating burner for heating and fusing the optical fiber held by the holding jig, and stretching the optical fiber heated and fused by the heating burner. An optical fiber fusion drawing apparatus, comprising: a stretching device, wherein the holding jig has a structure that moves left and right. 2. The optical fiber fusion drawing apparatus according to claim 1, wherein the holding jig is configured so that the moving distance thereof is controlled by a stopper.