Design and characteristics of reinforcement method for fusion spliced optical fiber

In developing a reinforcement method, optimum material and structure must be selected to prevent optical-fiber failure. This paper discusses a splice reinforcement element to compensate for shrinkage of the plastic coating due to aging and thermal cycling. In prior designs, shrinkage causes buckling and increases the failure probability of the reinforced section. Also, torsion propagation, introduced during fabrication of the splice, shows an adverse effect. These concepts have not been considered up to now and the new reinforcement method, using a heat shrinkable tube, shows good performance. The loss increase at a spliced portion without nylon coating, where a heat shrinkable tube is used, is below 0.02 dB at -70°C. It has also been verified that proof testing with approximately 15-kg/mm
²
proof stress is necessary for long-term durability of a spliced portion with a reinforcement element.