亚波长金属偏振分束光栅设计分析

结合有效介质理论和薄膜光学的抗反射设计方法，设计了基于0.65μm工作波长的亚波长金属偏振分束光栅，给出了光栅的优化设计参数，采用严格耦合波理论分析了光栅的偏振分束特性.结果表明，亚波长金属光栅对TE偏振表现为金属膜特性，具有高反射，对TM偏振表现为介质膜特性，具有高透射，在-30°<θ<30°的大入射角范围和0.47μm<λ<0.80μm的宽入射波谱内，该光栅的透射光和反射光均具有高偏振消光比和低插入损耗的特点.关键词：亚波长金属偏振分束光栅有效介质理论薄膜光学严格耦合波理论

Design of polarizing beam splitters based on subwavelength metal grating

A novel approach to design the subwavelength metal gratings for the polarizing beam splitters is presented. The method is based on effective medium theory （EMT） and thin film optics. The polarizing diffraction performance of subwavelength grating was analyzed by the rigorous couple-wave analysis （RCWA） for the wavelength of 650nm. The numerical calculus is used to analyze the effects of the zeroth diffraction efficiency caused by the grating period, the groove depth, the incident angle and the incident wavelength. The results show that subwavelength metal grating have the characteristics of high reflectivity like metal films for TE polarization and high transmission like dielectric films for TM polarization. Both transmission waves and reflected waves have high polarization extinction ratio and low insertion loss over a wide incident angle range （-30°<θ<30°） and a broad incident wavelength band （470nm<λ<800nm）. The optimal design agrees excellently well with the results simulated by RCWA method.