Yang Li-ling, Feng Guo-ying, Yang Hao, Zhou Guo-rui, Zhou Hao, Sui Zhan, Zhu Qi-hua
College of Electronics & Information Engineering, Sichuan University, Chengdu 610064, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2009 Sep;29(9):2489-93.
Starting from Nonlinear Schrodinger's equation and using the split-step Fourier method, the authors studied the characters of the supercontinuum generation of femtosecond laser pulse propagating in fused silica, and many physical factors were included such as propagation distance, input pulse peak power, diffraction effect, dispersion effect andnonlinear effect etc. The results show that when the femtosecond pulse propagated inside the fused silica, the process of supercontinuum generation could be divided into two main stages: the pulse compression stage, which was induced by the self-focus and other third nonlinear effects of the fused silica; and the pulse split stage, which was caused by the self-phase modulation and the group velocity dispersion of the fused silica. When the femtosecond pulse propagated inside the fused silica with high input peak power, the 3rd-order nonlinear effect of material induced pulse compression and then the subpulses were produced, so that new frequency components were introduced. At the same time, the authors also studied the spectral distribution of the pulse at different spacial locations, and there are new frequencies around the central frequency. Finally, some experiments were done to demonstrate the supercontinuum generation.
作者从非线性薛定谔方程出发，采用分步傅里叶方法研究了飞秒激光脉冲在熔融石英中传输时超连续谱产生的特性，考虑了传输距离、输入脉冲峰值功率、衍射效应、色散效应和非线性效应等诸多物理因素。结果表明，当飞秒脉冲在熔融石英内部传输时，超连续谱产生过程可分为两个主要阶段：由熔融石英的自聚焦和其他三阶非线性效应引起的脉冲压缩阶段；以及由熔融石英的自相位调制和群速度色散导致的脉冲分裂阶段。当飞秒脉冲以高输入峰值功率在熔融石英内部传输时，材料的三阶非线性效应引起脉冲压缩，进而产生子脉冲，从而引入新的频率成分。同时，作者还研究了脉冲在不同空间位置处的光谱分布，在中心频率附近出现了新的频率。最后，进行了一些实验来证明超连续谱的产生。
