Chen Xun, Wang Xinliang, Chen Haidong, Yang Xihang, Hu Jiabing, Bai Peile, Zhao Yang, Pan Shuren, Wu Fenxiang, Zhang Zongxin, Xu Yi, Leng Yuxin
Appl Opt. 2023 Oct 10;62(29):7791-7797. doi: 10.1364/AO.500272.
The temporal contrast of high-peak-power lasers is usually limited by pre-pulses, which are generally produced by post-pulses due to the nonlinearity of the active medium. The reason for the conversion between pre-pulse and post-pulse is now well known, but the mechanisms for the delay-shift and asymmetric broadening of the newly generated pre-pulse are not yet clear. In this work, a novel, to the best of our knowledge, numerical model combining the nonlinear Schrödinger equation and the Frantz-Nodvik equation is proposed to investigate the underlying mechanisms for the "distortion" of the pre-pulse. Numerical results show that the gain characteristics of Ti:sapphire amplifiers can only make a minor change on the temporal profile of the pre-pulse, but the high-order dispersion is the main cause for the delay-shift and asymmetric broadening of the pre-pulse, and the effects are more significant for the initial post-pulse with a relatively larger delay.
高峰值功率激光器的时间对比度通常受预脉冲限制，预脉冲一般由激活介质的非线性产生的后脉冲所导致。预脉冲和后脉冲之间转换的原因现已为人熟知，但新产生的预脉冲的延迟位移和非对称展宽机制尚不清楚。在这项工作中，据我们所知，提出了一种结合非线性薛定谔方程和弗兰兹 - 诺德维克方程的新颖数值模型，以研究预脉冲“畸变”的潜在机制。数值结果表明，钛宝石放大器的增益特性对预脉冲的时间轮廓只会产生微小变化，但高阶色散是预脉冲延迟位移和非对称展宽的主要原因，并且对于延迟相对较大的初始后脉冲，这些效应更为显著。
