Tunable circular conversion dichroism of single-layer twisted graphene-patterned metasurface

Yali Zeng; Qilin Duan; Jinying Xu; Zhilin Yang; Huanyang Chen; Yineng Liu

doi:10.1016/j.isci.2023.106115

Tunable circular conversion dichroism of single-layer twisted graphene-patterned metasurface

iScience. 2023 Feb 2;26(3):106115. doi: 10.1016/j.isci.2023.106115. eCollection 2023 Mar 17.

Authors

Yali Zeng¹, Qilin Duan¹, Jinying Xu², Zhilin Yang¹, Huanyang Chen¹, Yineng Liu¹

Affiliations

¹ Department of Physics and Institute of Electromagnetics and Acoustics, Xiamen University, Xiamen 361005, China.
² Department of Physics, Fuzhou University, Fuzhou 350108, China.

Abstract

Two-dimensional (2D) chirality-induced asymmetric transmission/reflection has great potential for polarization applications. Usually, asymmetric effects resulting from circular conversion dichroism (CCD) occur in chiral metasurfaces. Here, we propose a single-layer twisted graphene-patterned (with tilted elliptical hole arrays) metasurface and theoretically reveal its tunable CCD in the terahertz (THz) region. The unit cell of the metasurface is achiral. Merely by altering the in-plane orientation of holes for structural 2D chirality, a tunable CCD can be achieved at normal incidence. Interestingly, the reflection phase can be considered an intuitive method to show this metasurface's anisotropy, which complements the conventional CCD measurement in characterizing chiral materials. Furthermore, we can achieve active CCD based on the tunability of graphene. Due to the Fabry-Pérot resonance, a multiband enhancement of CCD spectrum will happen by changing the dielectric layer thickness. The proposed metasurface provides more flexible opportunities for designing active THz devices for polarization manipulation.

Keywords: Devices; Engineering; Nanomaterials.