800 nm亚波长夹层式金属偏振分束光栅

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 854 nm，以及入射角-27 27范围内，光栅的透射和反射消光比都大于20 dB，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。

Subwavelength sandwiched metal polarizing beam grating for 800 nm

In order to obtain high performance of polarization splitting grating, the subwavelength sandwiched metal grating structure was designed and analyzed. The optimal grating parameters were made by using the rigorous couple wave theory and genetic algorithm. Based on the optimized grating structure, high diffraction efficiencies of 98% and 96.5% can be achieved for TM transmission and TE reflection of 0th order in the 800 nm wavelength range, respectively. The optimized grating has an extinction ration of over 20 dB from 747 nm to 854 nm, and a large angle, from -27to 27, which met the expectations for high efficiency, high extinction ratio and wide spectrum and large angle. The fabrication tolerance around the optimized grating parameters was discussed, numerical results showed that the designed grating has good manufacture tolerance to period and groove depth and covering layer thickness. The subwavelength metal grating own many good characters such as simple structure, stable performance, low damage for the incident wave and obvious polarization, which will make the subwavelength metal grating have wide application prospect in the fields of optical polarizing elements, laser system, polarization imaging, etc.