Loose Tube Splices for Optical Fibers

The basic requirements for low-loss splices are (i) accurate alignment, (ii) good fiber ends, and (Hi) accurate diameter control. Transverse alignment accuracy of approximately ±0.1-fiber-core radius (typically, ±0.0001 in.) is required to achieve a splice loss of 0.1 dB. Good fiber ends may be produced by scoring and breaking, 1 grinding and polishing, or disc sawing. Accurate fiber diameter control is also needed; however, significant progress is being made in this area. Of these three requirements, accurate transverse alignment may be the most difficult problem to solve, especially when the field environment and variability of craftsmen's skill are considered. Single-fiber splicing has been accomplished by Bisbee2 and Dyott et aF using heat fusion. Someda 4 suggested using embossed plastic to obtain transverse alignment. This paper describes a splicing technique that uses a loose-fitting, square, cross-section tube to align the fibers. The splices produced are small, exhibit very low losses, and are simple and inexpensive. Previously, snug-fitting sleeves have been suggested,'' but three problems are usually encountered. 1215