基于光谱合束技术的透射光栅模拟设计

半导体激光器光谱合束技术能够实现近衍射极限的高功率激光输出，已成为当前研究热点。衍射光栅的性能直接决定光谱合束的激光输出效果。模拟设计了一种针对940 nm波长、熔融石英材料的亚波长透射光栅。基于严格耦合波理论对光栅结构进行初步设计，运用Rsoft软件依次对光栅占空比、脊高和周期等参数进行优化确定，同时分析了各个参数对光栅衍射效率的影响。所设计的透射式光栅实现第-1级衍射级次的波分复用功能，衍射效率达到91.2%(TE模式)，同时压缩其他衍射级次，使其衍射效率降到1.2%以下。同时在光栅入射角度59°±3°范围内保持90%以上的衍射效率，实现高功率激光输出的同时具有较高的误差容错率，易于调节，满足光谱合束技术的要求。

Simulation design of transmission grating based on spectral beam combining teachnique

Semiconductor laser beam splitting technology can achieve near-diffraction limit of high-power laser output, and has become the current research focus. Performance of diffraction grating directly determines laser output effect of spectral beam. A sub wavelength transmission grating for 940nm wavelength and fused silica material is simulated and designed. Based on strictly coupled wave theory, grating structure is designed, and parameters such as grating duty cycle, ridge height and period are optimized by Rsoft software. Influence of each parameter on diffraction efficiency of grating is also analyzed simultaneously. Designed diffraction grating achieves wavelength division multiplexing function of -1 diffraction order, diffractive efficiency reaches 91.2% for TE mode, and diffraction efficiency is reduced to 1.2% or less by compressing other diffraction orders. Diffraction efficiency of 90% or more is maintained within range of grating incidence angle of 59°±3°, meanwhile high power laser output has high error tolerance, and is easy to adjust to meet requirements of spectral beam combination technology.