Reduction of the cross-phase modulation impairment in wavelength division multipled systems with dispersion management

Summary form only given. Four wave mixing (FWM) and cross-phase modulation (XPM) processes are the most relevant impairments in wavelength division multiplexed (WDM) systems. The former causes generation of novel frequencies, the latter induces a phase shift on pulses crossing each other. In both effects the chromatic dispersion (GVD) of the fiber plays a significant role. Increasing the absolute value of the GVD, the efficiency of FWM effect decreases, but the XPM phase distortion is converted into intensity fluctuations. As a result, XPM is the main limitation for systems operating on step-index fibers. One method to limit XPM impairment is the periodical compensation of the GVD using dispersion managed (DM) links. Moreover, the DM technique improves the dispersion limited performance of each single channel, by propagating close to zero average GVD. In a previous work it was proved that nonlinear propagation in the regime of low normal dispersion may induce a amplitude-to-phase conversion of ASE noise. Clearly, this may lead to an improvement of the performance of IM-DD systems where the phase noise is discarded by the detecting photodiode. In analogy with the theory developed previously it can be numerically shown that in WDM DM links in which the pulses do not show significant strong shape distortion, the amplitude fluctuations due to the XPM can be converted to phase fluctuations in a regime of weak average normal dispersion; as a consequence this conversion may provide a method to control the XPM limitations.