多层介质膜脉冲宽度压缩光栅与超短脉冲作用时的性能分析

基于啁啾脉冲放大技术的超短脉冲激光系统是提供超快、超强激光的重要途径，具有良好输出波形和高损伤阈值的多层介质膜脉冲宽度压缩光栅是获得高峰值功率脉冲激光的关键. 基于傅里叶谱变换方法和严格模式理论，分析了多层介质膜光栅(MDG)在超短脉冲作用下的光学特性. 结果表明，当MDG的反射带宽小于具有高斯分布的入射脉冲的频谱宽度时，-1级反射脉冲呈非对称高斯分布，其前沿出现振荡，并且-1级反射脉冲能量开始剧烈下降. 讨论了MDG结构参数对其反射带宽的影响. 分析了MDG与超短脉冲作用时的近场光分布，对提高其抗激光损 关键词： 脉冲压缩光栅 傅里叶谱变换 模式理论 损伤阈值

Performance of multilayer dielectric grating irradiated by ultrashort optical pulse

In the ultrashort pulse high-energy laser system based on chirped pulse amplification technique, multilayer dielectric grating with good output waveform and high laser induced damage threshold plays an important role. Based on Fourier spectral transform and rigorous modal method, optical characteristic of multilayer dielectric grating under irradiation of ultrashort optical pulse is analyzed. The results show that the reflected pulse at the -1 order exhibits asymmetrical Gaussian shape with oscillatory tail in the front edge and decreasing energy when the reflection bandwidth is narrower than the frequency bandwidth of the incident pulse with Guassian shape. The effect of structure parameters of multilayer dielectric grating on the reflection bandwidth are discussed in detail, which provides guidance to the design of multilayer dielectric grating with desired reflection bandwidth. Finally, near-field distribution of multilayer dielectric grating is analyzed to study its damages induced by ultrashort pulses.