Role of the fusion splice in the concatenation problem

Near-field measurements used to derive an empirical model of a fusion splice have indicated that fusion splices generate very little mode coupling between multimode graded-index fibers of identical parameters. Results of dispersion measurements confirm this. In particular it is found that the bandwidth of a concatenated link of identical fibers (respliced fibers from the same preform) is determined by longitudinal profile variations and not splice characteristics. Fusion splices between nonidentical fibers can generate a larger degree of mode coupling. This unequal parameter-induced mode coupling has a measurable effect on file dispersion properties of concatenated fiber links.