In order to take full advantage of amplifier gain-bandwidth, and obtain a shorter pulse with higher power in the terminal, it is necessary to conduct a spectrum shaping before the seed pulse being injected into the main amplifier chain to compensate the effect of gain narrowing. A new method, based on the spatial grating with variable line-space for spectrum shaping of chirped laser pulse with the central wavelength at 1053 nm and line width 6 nm, is presented. The rigorous coupled-wave theory is used to analyze the characteristics of grating diffraction, and the results indicate that this method produces no phase distortion. The diffraction efficiency, as a function of the depth and period of groove, incidenct angle, and incident wavelength, is calculated and analyzed, respectively. With proper grating parameters, the spectrum modulation depth from 0.5% to 84% can be achieved.

为了充分利用放大介质的增益带宽, 获得脉宽更短, 功率更高的输出脉冲, 需要将输入到主放大链的种子脉冲进行光谱整形来补偿放大过程中的增益窄化效应。提出了利用变栅距反射光栅实现中心波长1053 nm, 谱宽6 nm啁啾脉冲的光谱整形。运用严格的光栅衍射耦合波理论分析光栅的衍射特性, 发现该方案不会引入相位畸变。分别计算和分析了刻槽深度、入射角大小、光栅周期以及入射光波长的变化对衍射效率的影响, 通过选取适当的光栅参量可获得0.5%～84%的光谱调制深度。