高阶效应对微结构光纤中超连续谱产生的影响

Influences of higher order effects on supercontinuum generation in microstructured optical fiber

采用分步傅里叶方法求解了广义非线性薛定谔方程(GNSE),数值模拟了飞秒激光脉冲在微结构光纤中的非线性传输和超连续谱的产生,详细分析了脉冲拉曼散射、自陡峭效应以及三阶色散对超连续光谱产生的影响。结果表明:超短脉冲在微结构光纤中传输时出现孤子自频移现象,同时也发现脉冲内拉曼散射和自相位调制的联合作用导致高阶孤子分裂,光谱得到极大展宽,在时域中出现两个滞后的拉曼孤子,三阶色散和自陡效应对光谱的形状影响较小,起着与脉冲内拉曼散射相反的作用,自陡效应比三阶色散效应对光脉冲的影响大一些。

The nonlinear generalized Schr5dinger equation is applied to describe the propagation of femtosecond laser pulses and supercontinuum generation in a microstructured optical fiber, and solved by using the split-step Fourier method. And the role of self-steepening, intra-pulse stimulated Raman scattering（SRS） and third-order dispersion are discussed adequately. The numerical results show that solition self-frequency shift is generated in a microstructured optical fiber. It is also found that intrapulse stimulated Raman scattering and self-phase modulation result in spectral broadening based on the fission of higher order solitions, and two lagging solitions occur in the time domain. The third-order dispersion and self-steepening influence on the shape of spectrum little, having the opposite effects with SRS. Self-steepening has relatively bigger influence on the ultra-short laser pulse than the third-order dispersion.