基于双多层介质膜衍射(MLD)光栅的超窄带光谱滤波系统可以获得普通窄带滤光片无法实现的亚纳米级超窄光谱滤波宽度, 利用该系统有望极大地提高激光回光探测系统的信噪比和抗干扰能力。设计了一套基于双MLD色散补偿光栅的超窄带光谱滤波系统, 使用CODE V软件对系统像差进行理论仿真, 发现系统像差可忽略不计; 使用Matlab软件对系统的滤波线宽和有效能量透过率进行理论仿真, 为解决实际滤波问题时, 根据实际需求选择最优系统结构参数提供了较完整的理论基础。最后, 在实验室采用国产多层介质膜光栅, 在1064 nm中心波长段, 成功将光谱半峰全宽(FWHM)为0.3 nm的入射激光转换为光谱FWHM为0.03 nm的出射激光。

The ultra-narrow band spectrum filtering system based on double multi-layer dielectric (MLD) coating diffraction gratings can achieve the sub-nanometer scale ultra-narrow spectral filter width that cannot be realized by common narrow band filter. Using this system may greatly improve the signal-to-noise ratio and anti-jamming ability of laser light echo detection system. An ultra-narrow band spectral filter system based on dual MLD dispersion compensation gratings is designed, and theoretical simulation of the system aberration is made using CODE V software. The result shows that the system aberration can be ignored. Also, theoretical simulation of the filtering linewidth and effective energy transmittance of the system is made by Matlab software, which provides a relatively complete theoretical basis for choosing the optimal structure parameters to solve the actual filtering problem in actual situation. Finally, by using domestic multi-layer film dielectric gratings in the laboratory, we successfully transform the input laser with spectrum full-width at half-maxima (FWHM) of 0.3 nm into the output laser spectrum FWHM of 0.03 nm, which is at center wavelength band of 1064 nm.