作　　者： (黄战华）; (马小青）; (朱攀）; (张亚男）; (蔡怀宇）; (张尹馨）;

机构地区： 天津大学精密仪器与光电子工程学院,天津300072 光电信息技术教育部重点实验室（天津大学）,天津300072

出　　处： 《光电工程》 2017年第7期663-669,共7页

摘　　要： 为提高长波红外偏振成像系统中偏振器件性能,本文通过分析光栅材料及结构参数对光栅偏振性能的影响,设计并优化了一种双层材料构成的亚波长光栅。该光栅为矩形形貌,光栅区由铝与硒化锌构成,两种材料的厚度分别为0.6μm和0.4μm,光栅周期1μm,占空比50%。利用严格耦合波理论分析并计算该结构光栅的衍射效率,7~15μm波段的光以0~60°入射后其0级横磁模透射率达到87.54%以上,消光比超过47 d B。该光栅在10.6μm的测试波长下,TM透射率高达90.80%且具有50 d B以上的消光比,相比槽深相同的单层铝光栅,偏振透过率明显提高。仿真结果显示,该光栅在整个宽长波红外波段具有良好的偏振性能。 A dual-layered sub-wavelength grating consisting of two kinds of materials, aluminum and ZnSe, is developed to improve the performance of polarimetric elements in long-wavelength infrared（LWIR） polarization imaging system. Parameters of the designed grating＇s morphological structure are optimized on the basis of analyzing the effects on the polarization performance through the rigorous coupled wave theory, which helpfully calculates the diffraction efficiency. With a rectangular profile, the grating designed for applications in LWIR band has periods of 1 μm and 50%-fill-factor. The depths of aluminum and ZnSe in the grating region are 0.6 μm and 0.4 μm respectively. A TM transmission greater than 87.54% with an extinction ratio exceeding 47 dB is achieved in the 7～15 μm band when the angle of incidence is from zero to sixty degree. The grating maintains an extinction ratio better than 50 dB and TM transmission over 90.80% above 10.6 μm incident wavelength, which is superior to single-layered aluminum gratings with the same depth in the transmission performance in comparison. The simulation results show that this grating has excellent polarization performance in the broad LWIR band.

关 键 词： 衍射光学 双层亚波长光栅 严格耦合波理论 线栅偏振器 长波红外