JP2001051149A - Optical fiber coupler and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber coupler easy to manufacture and handle, resistant to impact, with little fluctuation of characteristics. SOLUTION: This optical fiber coupler comprises a cylindrical quartz glass case 6 containing the fused part 2 of an optical fiber 1 fixed with a resin 3, an impact absorbing protective sheet 7 wound on the outside of the case 6, and a cylindrical protective tube 8 containing the case 6 wound with the protective sheet 7 and having both ends sealed with a resin 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical fiber coupler and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, an optical fiber coupler is formed by fusing a plurality of optical fibers at a portion where the coating layer is removed. Since the fused portion of such an optical fiber coupler is stretched and has an outer diameter of only about 30 μm and is easily broken, there is a disadvantage that handling at the time of packaging or the like is extremely difficult. Various attempts have been made to improve this, but no satisfactory optical fiber coupler has yet been obtained.

Japanese Patent Application Laid-Open No. 63-271208 discloses that the fused portion of an optical fiber coupler is suspended so that it does not come into contact with any part, and is fixed to a jig at a non-fused portion of an optical fiber to change the characteristics of the optical fiber coupler. Although a method for reinforcing the fused portion without performing the above is described, although the workability of handling is improved by this, when a strong impact is applied, the fused portion and its surroundings may be broken.

Japanese Patent Application Laid-Open No. H10-282359 discloses that a coating layer is formed on a fused portion of an optical fiber coupler with a UV-curable resin while monitoring the optical characteristics of the optical fiber coupler to obtain desired optical characteristics. At this point, it is described that the resin is cured with ultraviolet rays to provide sufficient reinforcement. In this reinforcing method, since the coating layer is formed while monitoring the optical characteristics, an optical fiber coupler having desired optical characteristics can be manufactured. Since the resin is directly coated on the fused portion of the coupler, if a heat cycle is applied to this portion, it is considered that the characteristics greatly fluctuate due to the difference in the coefficient of thermal expansion between the optical fiber and the resin.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical fiber coupler which solves the above-mentioned problems, is easy to manufacture and handle, is resistant to impact, and has a small variation in characteristics. .

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above problems as a result of intensive studies, and an optical fiber coupler according to the present invention has a tube in which a fused portion of an optical fiber is housed and fixed with resin. A quartz glass case, a shock-absorbing protective sheet wound around the outside of the case, and a cylindrical protective tube containing the case around which the protective sheet is wound and sealing both ends with resin, are provided. The glass case has a columnar shape including a lid portion and a base portion that are halved in the longitudinal direction. A sheet made of a resin foam, preferably a polyethylene or polystyrene resin foam, is used as the protective sheet.

The method for manufacturing an optical fiber coupler according to the present invention comprises:
After a plurality of optical fibers are fused and drawn, they are fixed with resin in a quartz glass case, a protective sheet for shock absorption is wrapped around the outside of the case, stored in a cylindrical protective tube, and both ends are sealed with resin. It is characterized by stopping.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG.
This will be described with reference to FIGS. FIG. 1 is a perspective view showing a state in which a fused portion 2 of a fused and drawn optical fiber 1 is housed in a lid portion 3 made of quartz glass which is halved in a longitudinal direction. The resin is adhered and fixed to the lid 3 at a non-fused portion slightly away from the fused portion 2. At this time, care must be taken so that the resin 4 does not adhere to the fused portion 2.
FIG. 2A is a longitudinal sectional view showing a quartz glass case 6 formed by joining the lid 3 and the half-column-shaped base 5.
(B) is a vertical cross-sectional view cut at substantially the center of (a).
This quartz glass case 6 has a protective sheet 7 made of a resin foam of polyethylene or polystyrene for absorbing shock.
Is wound around and housed in the central portion of the tubular protective tube 8, and both ends of the tubular protective tube 8 are sealed with resin, whereby the optical fiber coupler of the present invention is manufactured (see FIG. 3). .

At this time, as shown in FIG. 3, a cylindrical protective tube 8 having a longer overall length than the quartz glass case 6 is used.
The sealing is performed at a position slightly away from the quartz glass case 6. Note that it is preferable to use an ultraviolet curable resin for adhesion and sealing from the viewpoint of workability.

[0010]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto. (Embodiment) Four optical fiber couplers (1 × 8 couplers) of the present invention were manufactured by housing according to the procedure shown in FIGS. This optical fiber coupler has a holding condition of 0.5 m.
An impact test with an impact force of 1000 G was performed at s to confirm the presence or absence of disconnection. Before and after this impact test, the insertion loss of each port (Port) of the optical fiber coupler was measured, and the change in characteristics due to the impact was also confirmed. In the four optical fiber couplers subjected to the impact test, no disconnection occurred at all ports. In addition, the amount of change in insertion loss before and after the impact test is shown below. The change amount of the insertion loss indicates the value of the port having the largest change amount in each optical fiber coupler.

The coupler No. Maximum insertion loss change (dB) 0.17 2. 0.12 3. 0.19 4. 0.07

As described above, the optical fiber coupler manufactured by the method of the present invention has extremely high reliability against mechanical shock, and has an insertion loss before and after the shock test at all ports of each optical fiber coupler. Was suppressed to 0.2 dB or less.

[0013]

According to the optical fiber coupler of the present invention, the fused portion of the optical fiber is protected by a triple structure of a quartz glass case, a shock absorbing protective sheet and a cylindrical protective tube, so that the conventional optical fiber coupler is easy to break. The optical fiber coupler could be protected from impact. Further, by adopting a structure in which the fused portion does not touch any part, the variation of the characteristic value due to the impact can be suppressed to an extremely small value.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which a fused portion of an optical fiber that has been fused and drawn is housed in a lid portion 3 made of quartz glass that is half-split in a longitudinal direction.

FIG. 2A shows a lid portion 3 and a half-column cylindrical base portion 5;
FIG. 6 is a longitudinal sectional view showing a quartz glass case 6 formed by bonding the above, and FIG. 6 (b) is a longitudinal sectional view cut at substantially the center of FIG.

FIG. 3 is a longitudinal sectional view showing an optical fiber coupler of the present invention.

[Explanation of symbols]

 1. Optical fiber 2. Fused part 3. Lid 4. Resin 5. Base part 6. Quartz glass case 7. Protective sheet 8. Tubular protection tube

Continued on the front page (72) Inventor Atsushi Abe 2-3-1-1, Isobe, Annaka-shi, Gunma Prefecture Shin-Etsu Chemical Industry Co., Ltd. Precision Functional Materials Research Laboratories (72) Inventor Masatake Ejima 2--13, Isobe, Annaka-shi, Gunma Prefecture No. 1 Shin-Etsu Kagaku Kogyo Co., Ltd. Precision Functional Materials Research Laboratory (72) Inventor Shinji Makikawa 2-13-1, Isobe, Annaka-shi, Gunma Prefecture Shin-Etsu Kagaku Kogyo Co., Ltd.

Claims (4)

[Claims] 1. A cylindrical quartz glass case in which a fused portion of an optical fiber is housed and fixed with resin, a protective sheet for shock absorption wound around the outside of the case, and the protective sheet wound around the case. An optical fiber coupler comprising a cylindrical protective tube containing a case and sealing both ends with resin. 2. The optical fiber coupler according to claim 1, wherein the quartz glass case has a cylindrical shape including a lid and a base in a longitudinal direction. 3. The optical fiber coupler according to claim 1, wherein the protective sheet is made of a resin foam. 4. After a plurality of optical fibers are fused and drawn, they are fixed in a quartz glass case with a resin, and a protective sheet for absorbing shock is wrapped around the outside of the case and stored in a cylindrical protective tube. A method for manufacturing an optical fiber coupler, wherein both ends are sealed with a resin.