GB2164468A

GB2164468A - Optical fibre fusion splicing in dry gas

Info

Publication number: GB2164468A
Application number: GB08423079A
Authority: GB
Inventors: David Turner Parr
Original assignee: BICC PLC
Current assignee: Balfour Beatty PLC
Priority date: 1983-09-13
Filing date: 1984-09-12
Publication date: 1986-03-19
Also published as: GB8423079D0; GB2164468B; GB8324455D0

Abstract

To reduce the risk that an unsatisfactory fusion splice will be made in severe or unusual environmental conditions in the field, fusion splicing of aligned optical fibres is effected in the environment of a dry gas. The dry gas may be dry air but preferably is an inert gas such as nitrogen or argon. For this purpose, preferably the abutting ends of the aligned fibres are positioned in a leaky chamber 4 into which a charge of dry gas from a gas cylinder can be injected at a predetermined pressure through port 11, the rate of leakage of the dry gas from within the chamber being sufficiently slow to ensure that the chamber 4 is filled with dry gas during fusion splicing using electrodes 3. <IMAGE>

Description

SPECIFICATION Optical fibre splicing This invention relates to end-to-end fusion splicing of optical fibres.

Many techniques differing from one another have been proposed for effecting an end-toend fusion splice between optical fibres. Ideally, all of these fusion splicing techniques should be capable of being readily used in the field and a fusion splice made by any particular technique should be readily repeatable at any location and in any environmental conditions with confidence that a satisfactory fusion splice will be obtained.

It is an object of the present invention to provide an improved method of effecting an end-to-end fusion splice between optical fibres which substantially reduces the risk that an unsatisfactory fusion splice will be made in severe or unusual environmental conditions.

In the improved method according to the present invention, fusion splicing of the aligned optical fibres is effected in the environment of a substantially dry gas.

The dry gas employed may be dry air but preferably it is an inert gas such as nitrogen or argon.

Preferably, the aligned ends of the optical fibres are enclosed within a leaky chamber into which a charge of dry gas at a predetermined pressure can be readily injected, the rate of leakage of the dry gas from within the chamber being sufficiently slow to ensure that the chamber will be substantially filled with the dry gas during effecting of the fusion splice. Preferably, the chamber is constituted by a recess in the electrode block of the optical fibre aligning and splicing equipment into which the electrodes protrude and a preformed hood or cover of transparent material hinged or otherwise attached to the block.

The source of dry gas may be a small gas cylinder mounted within the housing of the optical aligning and splicing equipment and having a pipe which opens into the chamber.

Alternatively, the dry gas may be blown across the region of the splice prior to and during the fusion splicing process. For this purpose, dry gas ejector ports, preferably with nozzles directed towards the region of the splice, may be incorporated in optical fibre clamps of the optical fibre aligning and splicing equipment and may be connected to a source of dry gas, such as a small gas cylinder, mounted within the equipment.

In all cases, the dry gas injected into the chamber or blown across the region of the splice is at a substantially constant temperature.

The invention also includes apparatus for effecting an end-to-end fusion splice of optical fibres by the improved method hereinbefore described.

The invention is further illustrated by a description, by way of example, of the preferred apparatus for and method of effecting a fusion splice of aligned optical fibres with reference to the accompanying drawing in which: Figure 1 is a fragmental side view, partly in section and partly in elevation, of the preferred apparatus, and Figure 2 is a fragmentai plan view of the preferred apparatus.

Referring to the drawing, the apparatus includes an electrode block 1 in which there is a recess 2 of substantially U-shape into which protrude electrodes 3 for effecting fusion splicing of two aligned optical fibres (not shown) which are introduced into the recess through its U-shaped open sides. The optical fibres are supported on chucks (not shown) which are adjustable in a rectilinear direction towards and away from the electrodes.

The recess 2 is partially closed by two side walls 7 of transparent plastics material secured to the sides of the electrode block 1 and can be temporarily closed to form a leaky electrode chamber 4 by a preformed hood 8 of transparent plastics material which is pivotally mounted on the block and which, in the closed position, rests on the upper edges of the side walls 7. The abutting edges of the side walls 7 and hood 8 and upper parts of the block 1 bounding the electrode chamber 4 support seals 9 of elastomeric material. Openings 10 between the abutting edges of the side walls 7 and hood 8 permit entry of the leading ends of the chucks into the electrode chamber 4 in order to facilitate alignment of the optical fibres.A port 11 opening into the electrode chamber 4 is connected by a flexible tube 12 to a cylinder (not shown) containing argon and mounted in the housing of the apparatus. Controlled leakage of argon from within the electrode chamber 4 when closed by the hood 8 takes place through the openings 10 and between the side faces of the electrode block 1 and the side walls 7 and hood 8.

In an alternative embodiment, the side walls 7 may be carried by the chucks supporting the optical fibres and may have on parts of their leading faces layers of elastomeric material for engaging the side walls of the electrode block 1 when the chucks are moved towards the electrodes to effect alignment of the optical fibres.

In use, before the optical fibres to be fusion spliced are finally aligned with their ends substantially abutting, the hood 8 is closed to form the leaky electrode chamber 4 and, by appropriate adjustment of the chucks, the optical fibres are finally aligned with their ends substantially abutting ready for fusion splicing.

A charge of argon is then injected into the electrode chamber 4 through the port 11 so that the chamber is substantially filled with argon under pressure and fusion splicing of the aligned abutting optical fibres is effected, the rate of leakage of argon from within the chamber being sufficiently slow to ensure that the chamber is substantially filled with argon during the fusion splicing operation.

The improved method of the present invention has the important advantage that fusion splices of optical fibres can be effected under substantially identical conditions at locations in the field where environments of humidity differ from one another, thereby substantially reducing the risk that an unsatisfactory fusion splice will be made.

Claims

1. A method of effecting an end-to-end fusion splice between optical fibres, wherein fusion splicing of the aligned optical fibres is effected in the environment of a substantially dry gas.

2. A method as claimed in Claim 1, wherein the aligned ends of the optical fibres are enclosed within a leaky chamber and a charge of dry gas at a predetermined pressure is injected into the chamber, the rate of leakage of the dry gas from within the chamber being sufficiently slow to ensure that the chamber is substantially filled with dry gas during effecting of the fusion splice.

3. A method as claimed in Claim 2, wherein the source of dry gas is a gas cylinder mounted within the housing of the optical fibre aligning and splicing equipment and having a pipe which opens into the chamber.

4. A method as claimed in Claim 1, wherein the dry gas is blown across the region of the splice prior to and during the fusion splicing process.

5. A method as claimed in Claim 4, wherein the dry gas is blown from ejector ports incorporated in optical fibre clamps of the optical fibre aligning and splicing equipment and connected to a gas cylinder mounted within the housing of the equipment.

6. A method as claimed in any one of the preceding Claims, wherein the dry gas is at a substantially constant temperature.

7. A method as claimed in any one of the preceding Claims, wherein the dry gas is an inert gas such as nitrogen or argon.

8. A method as claimed in any one of Claims 1 to 6, wherein the dry gas is dry air.

9. For effecting an end-to-end fusion splice between optical fibres, apparatus comprising an electrode block having a recess into which electrodes protrude and, for temporarily closing the recess to form a leaky electrode chamber for enclosing the aligned ends of optical fibres to be spliced, a preformed hood or cover of transparent material hinged or otherwise attached to the block, and a gas cylinder containing dry gas connected to a port opening into the leaky chamber, the degree of leakage of dry gas from within the chamber being such that, during effecting of a fusion splice, the chamber can be substantially filled with dry gas.

10. For effecting an end-to-end fusion splice between optical fibres, apparatus comprising optical fibre aligning and splicing equipment incorporating optical fibre clamps having ejector ports therethrough and a gas cylinder containing dry gas and connected to said ports, whereby dry gas can be blown across the region of the splice prior to and during the fusion splicing process.

11. Apparatus as claimed in Claim 10, wherein the dry gas ejector ports have nozzles directed towards the region of the splice.

12. A method of effecting an end-to-end fusion splice between optical fibres substantially as hereinbefore described with reference to the accompanying drawing.

13. Apparatus for effecting an end-to-end fusion splice between optical fibres substantially as hereinbefore described with reference to and as shown in the accompanying drawing.