亚纳秒脉冲泵浦机制超短脉冲和超连续谱的产生

Generation of Ultra-short Pulses and Supercontinuum in the Sub-nanosecond Pulse Pumping Regime

本文仿真研究了亚纳秒脉冲泵浦机制超短脉冲的产生和超连续谱的形成。首先,简要介绍了激光在非线性介质传输所满足的广义非线性薛定谔方程;然后,研究了分步傅里叶法时域步长的选取和空间步长高精度自适应变化的实现;最后,逐渐增加入射脉冲的峰值功率,仿真了超连续谱的形成。结果表明:亚皮秒量级的超短脉冲可以由亚纳秒脉冲经过调制不稳定性分裂产生,而与超短脉冲有关的高阶非线性效应(包括自陡效应、脉冲内拉曼散射效应、高阶孤子分解)最终导致了30 dB带宽从481 nm一直延伸到1 750 nm超连续谱的形成。

The generation of ultra-short pulses and the formation of supercontinuum in the sub-nanosecond pulse pumping regime have been simulated. First of all, we briefly introduced the generalized nonlinear Schrodinger equation, which could effectively describe laser propagation in the nonlinear medium. The choice of temporal resolution and the high-accuracy adaptive change of step size were secondly studied for the split-step Fourier method. The formation of supercontinuum was finally researched by gradually increasing the peak power of incident pulse. The results showed that sub-picosecond pulses could be generated from the breakup of sub-nanosecond pulse owing to modulation instability, and the higher-order nonlinear effects of ultra-short pulses, including self-steepening, intrapulse Raman scattering, the fission of higher-order soliton, lead to the formation of supercontinuum spanning from 481 nm to1 750 nm of 30 dB bandwidth.