亚波长介质偏振分束光栅的衍射特性

Diffraction characteristics of polarizing beam splitters based on subwavelength dielectric grating

采用严格耦合波理论并结合矩阵LU分解法,分析了亚波长介质光栅的刻槽深度、占空比、入射角、入射波长等参数对TE偏振和TM偏振0级衍射效率的影响。结果表明:在1550 nm波长处,出现瑞利反常现象。由此提出利用瑞利反常现象设计工作波长为1550 nm的偏振分束光栅,通过优化设计确定了最佳设计参数,即光栅周期为λ0/2,瑞利入射角为30°,刻槽深为0.9λ0,占空比为0.5。结果表明,参数优化后的偏振分束光栅可以使TE偏振0级反射波和TM偏振0级透射波同时达到近100%的衍射效率。

A novel approach to the design of the polarizing beam splitters based on the subwavelength dielectric grating is presented. Using rigorous coupled-wave theory and matrix LU decomposition, the Rayleigh anomaly and the effects of the grave depth, the duty cycle, the incident angle and the incident wavelength on the diffraction efficiency were investigated. The results show that at the incident wave length of 1 550 nm, the grating period of λ0/2, the Rayleigh incident angle of 30°, the grave depth of 0.9λ0 and the duty cycle of 0.5, using Rayleigh anomaly the TE polarization and TM polarization diffraction efficiency of 0-or der reached nearly 100% at the same time.