色散缓变光纤中五阶非线性调制不稳定性

在三五阶非线性共存时,研究了有损耗单模光纤中基于两光波交叉相位调制的不稳定条件和增益谱.在色散缓变光纤正色散区,分析了五阶非线性系数、色散纵向变化参量以及两扰动的频率大小关系对交叉相位调制不稳定增益谱的影响.结果表明,在五阶非线性下,色散的纵向渐减仍有利于展宽调制不稳定增益谱;正五阶非线性可使增益谱的谱宽和谱峰值增大,并使谱峰位置远离主波频率,负五阶非线性的作用则相反;两扰动频率大小关系不同,色散纵向参量的变化对增益谱的谱峰大小和位置的影响也不同,五阶非线性对交叉相位调制不稳定性的加强或抑制程度也不同.

Modulation instability in the decreasing dispersion fibers with quintic nonlinearity

In case of co-existence of cubic and quintic nonlinearity,the condition and power gain spectra of modulation instability induced by the cross-phase modulation for two optical waves in loss,single-mode optical fibers are studied.In the normal dispersion region of the decreasing dispersion fibers,the effects of the quintic nonlinear coefficients,the dispersion longitudinal varying parameters,and the size relation of the two perturbation frequencies on the power gain spectra of modulation instability are analyzed in detail.The results indicate that,in case of quintic nonlinearity,the longitudinal decreasing of dispersion is still benefit to broaden the gain spectra of modulation instability.The positive quintic nonlinearity will make the width and the peak value of the gain spectra larger,and make the position of peak value be far away from the frequency of the main wave,while the negative quintic nonlinearity will do the opposite.If the size relation of the two perturbation frequencies is different,the dispersion longitudinal varying parameters will influence the position and value of the spectrum peak in different ways,and the quintic nonlinearity will intensify or suppress the modulation instability to different degrees.