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为获得高性能的偏振分束光栅,设计了一种亚波长夹层式金属光栅结构,通过严格耦合波分析和遗传算法优化出最佳光栅结构。所设计的光栅在波长为800 nm时,0级衍射级次上TM偏振波的透射率和TE偏振波的反射率分别为98%和96.5%。在波长747 nm<λ<854 nm,以及入射角-27°<θ<27°范围内,光栅的透射和反射消光比都大于20 d B,达到了高衍射效率、高消光比、宽带宽及大角度的要求,数值分析表明该光栅对周期、槽深、覆盖层厚度具有优良的工艺容差。该光栅结构简单,性能稳定,对入射光损耗低,偏振分束效果明显,在光学偏振器件、激光器系统、偏振成像等领域具有广泛的应用前景。
In order to obtain high-performance polarization beam splitter, a sub-wavelength laminated metal grating structure is designed, and the optimal grating structure is optimized through strict coupling wave analysis and genetic algorithm. The designed grating has the reflectivity of 98% and 96.5% of TM polarized wave and TE polarized wave respectively at 0 order of diffraction at the wavelength of 800 nm. In the range of 747 nm <λ <854 nm, and the incident angle -27 ° <θ <27 °, the transmission and reflection extinction ratios of the gratings are all greater than 20 d B, achieving high diffraction efficiency, high extinction ratio, wide bandwidth and Large-scale requirements, numerical analysis shows that the grating on the cycle, groove depth, the thickness of the cover has excellent process tolerance. The grating has the advantages of simple structure, stable performance, low loss of incident light and obvious polarization splitting effect, and has wide application prospect in the fields of optical polarization device, laser system and polarization imaging.