title: Achromatic phase retarder applied to MWIR & LWIR dual-band.
abstract: 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.
authors.affiliation: State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing, China. kenandlily@tom.com
authors.forename: Guoguo
authors.initials: G
authors.lastname: Kang
authors.forename: Qiaofeng
authors.initials: Q
authors.lastname: Tan
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Wang
authors.forename: Guofan
authors.initials: G
authors.lastname: Jin
mesh_terms: D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007259:Infrared Rays; D055096:Optical Devices; D012031:Refractometry / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity