High Reliability Splicing Of Single Mode Fibres

Splicing of optical fibres is a key aspect of the manufacture and installation of both landline and submerged optical fibre systems. In many landline applications the splices are housed in large cable joints and are not subjected to any strain in service. A number of techniques have been described in the literature (refs. 1-3) that are suitable for these relatively benign environments. They generally employ solvents and/or mechanical methods to remove the fibre primary and secondary coatings before cleaving and aligning the fibre ends in a splicing machine. Some of these techniques are also suitable for use in submarine cable systems where a cable joint housing is used between lengths of optical cable (ref.4). However, for efficient cable manufacture and lay it is desirable that the cable should be produced in repeater section lengths. Since fibre is not yet produced in such lengths it is necessary to splice sections together and to reinstate the primary and secondary coatings over the splice with the same diameter as the parent fibre coating. As these splices will be incorporated directly into a cable they will be subjected to the same manufacturing and service strains as the fibre and must therefore have high strength. Submarine systems must also be extremely reliable, which demands high reliability from the splices over the 25-year design life of the system. This paper describes the process developed to produce high strength splices reliably and the results of dynamic and static fatigue testing are given. The process is now in production at STC-Submarine Systems Ltd.