亚波长光栅用于实现宽光谱消色散1/4波片的研究

基于严格耦合波理论 ,分析了共振区域矩形位相光栅的衍射特性 :位相延迟与光栅周期、占空比、槽深的关系 ,并设计出在 40 0～ 80 0nm范围内的消色散 1/4波片光栅 ,可以实现较为平坦的衍射效率和位相延迟曲线 ,其中位相延迟可保持在 90°左右 ,最大偏差小于 9% ,达到甚至优于普通二元复合消色散波片。通过对加工及安装误差的讨论 ,得到了影响消色散波片光栅性能的主要加工误差是槽深误差和占空比误差。

Study on Broadband Achromatic Quarter-wave Plate by Subwavelength Gratings

Based on rigorous coupled wave theory, the relationship between diffraction property of rectangular phase gratings in resonant region and grating period, duty cycle, thickness is analyzed. An achromatic quarter wave grating for 400～800 nm is designed. In the broadband, the grating has smooth efficiency and phase retardation. Specially, the phase retardation could maintain about 90°, and the maximum retardation deviation is less than 9%. Its performance is even better than some normal binary achromatic wave plates. With the analysis of fabrication error, it is noted that thickness error and duty cycle error affect the grating′s performance greatly.