Modulational instability in nonlinear birefringent step-wise decreasing fiber with higher-order dispersion

摘要

Modulational instability (MI) of electromagnetic waves in nonlinear birefringent step-wise decreasing fiber with coexistence of cubic and quintic nonlinearity is investigated by the coherently coupled nonlinear Schrodinger equation. The properties of MI gain are studied. The results show that , the procedure occurred not only in the normal dispersion regime but also in abnormal dispersion regime. The positive quintic nonlinearity index intensifies the modulation instability , making the width of the gain spectra of MI become wider and the peak gain higher, otherwise, suppresses the modulation instability. MI gain changes according to the distance propagated, and the gain spectra will change with token distance series.