不同入射脉冲强度线性啁啾对BaF2晶体交叉偏振波输出特性影响的数值模拟研究

在超短飞秒激光技术中, 基于BaF₂晶体三阶非线性效应的交叉偏振波技术是目前最重要的提高脉冲时域对比度的手段之一. 针对不同入射脉冲强度下入射脉冲的线性啁啾对BaF₂晶体交叉偏振波的输出特性, 包括转换效率、光谱加宽和时域压缩的影响进行了详细的数值模拟和讨论.特别地, 详细对比研究了非饱和及强入射脉冲情况下线性啁啾对交叉偏振波输出脉冲光谱加宽的影响. 结果表明, 在强入射脉冲情况下, 交叉偏振波的光谱加宽量从非饱和情况下相对于零点线性啁啾时的对称结构, 变得不再具有对称性, 并对产生非对称性的原因进行了详细的物理解释.

Investigation on the influences of linear chirp with different input pulse intensities on BaF2 cross-p olarized wave generation

Cross-polarized wave (XPW) generation based on BaF₂ crystal is one of the most important tools in improving the contrast of ultra-intense femtosecond laser pulses at present. In this paper, the influences of linear chirp with different input pulse intensities on BaF₂ XPW generation, including conversion efficiency, spectrum broadening, and pulse duration reduction are in detail simulated and discussed. Especially, the influence of linear chirp on spectrum broadening is comparatively investigated under unsaturated and intense input pulses. While the amount of spectrum broadening relative to linear chirp is symmetrical with respect to the zero chirp point under unsaturated input pulse, the results show that it is no longer those in the case under intense input pulse, and the intrinsic reason is explained in detail in this paper.