初始啁啾对脉冲频谱演变的影响

本文从理论上分析了色散和非线性对脉冲频谱的影响 ,采用数值方法求解了非线性薛定谔方程的频域解。模拟了初始啁啾对不同形状脉冲频谱的作用。研究结果表明 :初始啁啾对频谱的影响随脉冲形状而变化。对高斯型脉冲 ,正的初始啁啾导致频谱严重展宽 ,负初始啁啾对频谱影响较小。超高斯型脉冲的频谱出现了旁瓣 ,这会引起能量的损失 ;而初始啁啾对其频谱的影响并不大。孤子型脉冲的频谱受初始啁啾的影响较大 ,尤其是高阶孤子。因此 ,为了保证脉冲稳定传输 ,必须消除初始啁啾。

Influence of Initial Chirp on the Evolution of Spectra

The influence of dispersion and nonlinearity on the spectra was analysed. The nonlinear Schr?dinger equation was solved numerically in the frequency domain. The effect of the initial chirp on the spectra of different formats was simulated. It was found that the influence of the initial chirp on the spectra changed with different formats. The positive initial chirps make spectra spreading and negative initial chirps have little influence upon spectra for Gauss pulses. For super Gauss pulses, the spectra have some side tails, which cause energy loss, but the initial chirp has very little effect on the spectra. The initial chirps have a great influence on the spectra for soliton pulse, especially for high order soliton, which suggests that initial chirp must be decreased for stable pulse transmission.