色散缓变光纤中高阶色散和高阶非线性下的交叉相位调制不稳定性

Cross-phase Modulational Instability with High-order Dispersion and High-order Nonlinearity in Decreasing Dispersion Fiber

从包含高阶色散和高阶非线性的广义非线性薛定谔方程出发,理论上推导了色散缓变光纤(DDF)中交叉相位调制(XPM)不稳定增益谱,分析了4阶色散、5阶非线性系数以及光纤纵向色散参量对增益谱的影响.数值仿真结果表明:在DDF的正、反常色散区,4阶色散导致XPM不稳定均发生在两个频谱区.正(负)5阶非线性使增益谱的谱宽和峰值增大(减小).DDF中XPM不稳定增益谱宽比常规光纤的宽,且随着光纤纵向色散参量的增大,DDF中XPM不稳定越来越明显.

The cross-phase modulation（XPM） instability in decreasing dispersion fiber（DDF） is investi- gated based on extended nonlinear Schrodinger equation with high-order dispersion and high-order nonlinearity considered. The effects of fourth-order dispersion, quintic nonlinearity and axilly-varying dispersion parameter to the gain spectra are analyzed. The results show that XPM instability occurs at two spectrum regions in both the normal and the anomalous dispersion regimes of fiber because of fourth-order disper- sion. The positive （negative） quintic nonlinearity make the width and the peak value of the gain spectra larger （smaller）. The spectrum width of XPM instability in DDF is larger than that in common fiber, and the spectrum width in DDF increases with the increasing of axilly-varying dispersion parameter.