色散缓变光纤中高阶色散导致的交叉相位调制不稳定性分析

In this paper, we derive the gain spectra of XPM-induced modulation instability in dispersion-decreasing fiber (DDF) from the generalized nonlinear Schr鰀inger (NLS) equation which contains high-order dispersion, study with the gain spectra versus the ratio of incident powers of two optical waves and the vertical dispersion parameter. The research shows that: As the fourth-order dispersion, in the normal and anomalous dispersion regions of DDF, XPM-induced modulation instability both occurs in two spectra regions. Both of the two spectrums in the anomalous dispersion region are wider than in the normal dispersion region, and the second spectra region in the anomalous dispersion region is closer to zero, which shows that in the DDF, it抯 easier for XPM-induced modulation instability to occur in the anomalous region. The widths of two gain spectrums in the normal and anomalous dispersion regions increase as the ratio of incident powers increases, and the gain spectra width is wider in DDF than in normal fibers, and XPM-induced modulation instability in DDF is more and more obvious as the vertical dispersion parameter increases.