Circular Polarization Discrimination Enhanced by Anisotropic Media

• Published in: Advanced optical materials 2020-05, Vol.8 (9), p.n/a
• Main Authors: Chu, Zeshi, Zhou, Jing, Dai, Xu, Li, Fangzhe, Lan, Mengke, Ji, Zhaoyu, Lu, Wei, Chen, Xiaoshuang
• Format: Article
• Language: English
• Subjects: Absorptance; Absorptivity; Anisotropic media; Anisotropy; asymmetric metamaterials; Asymmetry; Circular polarization; circular polarization discrimination; Composite structures; Discrimination; double polarization selection; Extinction; infrared circular polarization detection; Materials science; Metamaterials; Nanowires; Optics; Optoelectronics; Quantum wells
• ISSN: 2195-1071; 2195-1071
• DOI: 10.1002/adom.201901800

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. The circular‐polarization‐discriminative light–matter interaction can be characterized by the circular polarization extinction ratio (CPER) for the absorption of the active material. The value for an asymmetric metamaterial‐integrated isotropic active material is typically below 2.5. By substituting the isotropic active medium with an anisotropic one, the CPER can be drastically enhanced by 6–10 times.