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利用二维结构薄膜构建了具有偏振选择特性的新型相位光栅,借助严格耦合波分析(RCWA)方法计算了光栅各级衍射强度随入射光波长及入射角的变化,发现在垂直入射情况下,波长600—640nm范围内,相位光栅对横向电学(TE)模主要产生0级衍射,而对横向磁学(TM)模产生±1级衍射,在波长633nm处,0级衍射光的偏振消光比为109.8,±1级衍射光的偏振消光比为334.6.利用时域有限差分方法对这种相位光栅的偏振分束现象进行了模拟,偏振分离角在玻璃基板内可以达到10°左右,最后模拟了入射角为23°时光栅对不同偏振态入射光的衍射效果,并与RCWA计算结果和光栅方程计算结果进行了比对.
A novel phase grating with polarization selectivity was constructed by using a two-dimensional structure film. The diffraction intensity at various diffraction gratings with incident light wavelength and incident angle was calculated by the RCWA method. It was found that under normal incident conditions, the wavelength In the range of 600-640nm, the phase grating mainly produces 0-order diffraction for transverse mode (TE) mode and ± 1 order mode for transverse mode (TM) mode. The polarization extinction ratio of 0 order diffracted light is 109.8, the polarization extinction ratio of ± 1 order diffracted light is 334.6. The polarization splitting phenomenon of this phase grating is simulated by finite difference time-domain method. The polarization splitting angle can reach about 10 ° in the glass substrate. Finally, The diffraction effect of the grating on the incident light with different polarization states at 23 ° incidence angle is compared with that of the RCWA calculation and the grating equation calculation.