Circular Polarization Discrimination Enhanced by Anisotropic Media

Circular polarization discrimination is desired for use in many optoelectronic applications. By integrating asymmetric metamaterials with active materials, circular-polarization-discriminative light-matter interaction can be realized. Nevertheless, the circular polarization extinction ratio for absorption of the active materials, typically below 2.5, needs to be improved. Here, it is revealed that the integration of an asymmetric metamaterial with an anisotropic material can drastically enhance the circular polarization extinction ratio by six to ten times. This enhancement is attributable to a double polarization selection mechanism. This discovery is important to circular-polarization-discriminative optoelectronics since anisotropic optoelectronic materials are easy to find. It is demonstrated that asymmetric metamaterial-integrated quantum wells (anisotropic) exhibit a circular polarization extinction ratio of 14 in the long-wave infrared regime, compared with the value of 1.3 for the same integrated HgCdTe (isotropic). Similarly, the asymmetric metamaterial-integrated InAsSb nanowire array (anisotropic) exhibits a circular polarization extinction ratio of 12.6 in the mid-infrared regime, compared with the value of 1.7 for the same integrated InAsSb bulk (isotropic). The absorptance of the anisotropic material in the composite structure is also significantly enhanced.