宽光谱高衍射效率脉宽压缩光栅设计和性能分析

Design and Diffraction Property of Broad Waveband High-Diffraction-Efficiency Grating for Chirped Pulse Compressor

基于飞秒激光对脉宽压缩光栅宽光谱和高衍射效率的要求,提出了一种金属介质膜结构的宽光谱高衍射效率脉宽压缩光栅,该光栅由基底、金属介质膜和表面浮雕结构组成。为获得宽光谱高衍射效率的脉宽压缩光栅,采用严格耦合波理论对金属介质膜光栅的结构参数进行优化设计。数值分析表明当金属介质光栅的槽深、剩余厚度、占空比和入射角分别为272nm,10nm,0.23和54°时,对于中心波长为800nm的TE波,其-1级衍射效率在732～886nm内优于97%,有效工作带宽达150nm。

The grating used for chirped pulse compressor should have broad waveband and high diffraction efficiency.A metal-multilayer-dielectric grating（MMDG） with broad waveband and high diffraction efficiency is proposed to stretch and compress chirped pulse.It consists of three parts as substrate,metal and multi-layer dielectric mirror and surface relief structure.Rigorous coupled-wave analysis is employed to analyze the diffraction property of MMDG to extend working waveband and improve the diffraction efficiency.Simulation results show that when the groove depth,residual thickness,duty cycle and incident angle are 272 nm,10 nm,0.23 and 54° respectively,the average diffraction efficiency is higher than 97% for TE polarized light over the 150 nm bandwidth centered at 800 nm as the wavelength changes from 732 to 886 nm.