Optimizing the location of dispersion compensators in periodically amplified fiber links in the presence of third-order nonlinear effects

In order to minimize third-order nonlinear effects while compensating dispersion in a periodically amplified link, it is more effective to place a single dispersion compensator at the end of the link than to individually compensate each segment. The improvement obtained by using the former approach instead of the latter one, defined as the ratio of the powers of the four-wave mixing products in the two cases, is (sin N u/N sin u)/sup 2/ where N is the number of segments, and u represents phase mismatch. We have experimentally verified this conclusion, by performing a cross-phase modulation experiment in a two-segment link.