Reduction of four-wave-mixing cross talk in WDM systems using unequally spaced channels

Abstract

Very-high-capacity long-haul optical communication systems without intermediate optoelectronic conversions can be conceived by using erbium-doped-fiber amplifiers and wavelength-division multiplexing (WDM). The effects of chromatic dispersion and nonlinearities, however, accumulate during propagation, thus severely limiting the achievable performance. The use of dispersion-shifted fiber permits higher bit rates but enhances the efficiency of four-wave-mixing (FWM) wave generation by reducing the phase mismatch that is naturally provided by the fiber dispersion,1 thus causing FWM to become the dominant nonlinear effect.2