Tunable terahertz circular dichroism based on graphene-metal hybrid metasurface

Abstract

Chiral metasurface shows a strong ability to control circularly polarized electromagnetic waves, and the introduction of dynamic-manipulation will further expand the application potential for chiral meta-devices. In this paper, we propose a new scheme to realize tunable chiral terahertz devices. By introducing patterned monolayer graphene into the reflective chiral metal meta-atoms, the chiral terahertz response of the metasurface is efficiently and dynamically adjusted, and its reflective circular dichroism value gradually changes from -0.7 to -0.2. In addition, the change of the incident angle may cause the symbol inversion of circular dichroism and change it from single-band to multi-band. We analyze the physical mechanism of tunable chiral response caused by Fermi level of graphene and the principle of the dynamic change of reflection circular dichroism. The proposal of this scheme provides a new idea for the dynamic tuning of chiral metasurfaces and promotes the development of tunable terahertz meta-devices.