Kang Guoguo, Tan Qiaofeng, Wang Xiaoling, Jin Guofan
State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing, China.
Opt Express. 2010 Jan 18;18(2):1695-703. doi: 10.1364/OE.18.001695.
The development of the dual-band IR imaging polarimetry creates the need for achromatic phase retarder used in dual-band. Dielectric grating with the period smaller than the illuminating wavelength presents a strong form-birefringence. With this feature, the combination of several subwavelength gratings can be used as achromatic phase retarders. We proposed a combination of 4 subwavelength structured gratings (SWGs) used as an achromatic quarter-wave plate (QWP) applied to MWIR & LWIR bandwidths. Design method using effective medium theory and optimization algorithms is described in detail. The simulation results led to the possibility of an dual-band achromatic QWP whose retardance deviates from 90 degrees by <+/-0.75 degrees with the fast axis unfixed and by <+/-1.35 degrees with the fast axis fixed over MWIR(3-5microm) & LWIR(8-12microm) bandwiths.
双波段红外成像偏振测量技术的发展催生了用于双波段的消色差相位延迟器的需求。周期小于照明波长的介质光栅呈现出很强的形状双折射特性。利用这一特性，几个亚波长光栅的组合可被用作消色差相位延迟器。我们提出了一种由4个亚波长结构光栅（SWG）组成的组合，用作应用于中波红外（MWIR）和长波红外（LWIR）带宽的消色差四分之一波片（QWP）。详细描述了使用有效介质理论和优化算法的设计方法。仿真结果表明，有可能实现一种双波段消色差QWP，其延迟在中波红外（3 - 5微米）和长波红外（8 - 12微米）带宽范围内，快轴未固定时偏离90度<±0.75度，快轴固定时偏离90度<±1.35度。
