Further analysis of modulation instability induced by cross-phase modulation

Based on the coupled nonlinear Schrdinger equation,conditions and gain spectra of modulation instability(MI) induced by cross-phase modulation(XPM) of two optical waves in the optical fiber are analyzed in detail. The results show that when one of the two optical waves propagates in the normal group-velocity dispersion (GVD) regime and the other in the anomalous regime,depending on parameters of the two optical waves,perturbation gain spectra may take three possible forms. Under certain circumstances,it is even possible that there are two forms of gain spectra within certain range of perturbation frequency.