Hybrid tunable chiral metasurfaces for amplitude and wavefront control of circularly polarized terahertz wave

Abstract

Chiral metasurfaces can realize strong chiral optical responses and various spin-dependent electromagnetic manipulations. In this paper, we propose a metal-graphene hybrid metasurface that achieves active control of the amplitude and wavefront of reflected circularly polarized terahertz wave. By introducing a single layer graphene at the bottom of the patterned metasurface, combined with the silicon layer for voltage control, continuous change of the circular dichroism (CD) from 0 to 0.6 is obtained. Then we realized dynamic switching of the terahertz beam from anomalous reflection to vertical reflection using Pancharatnam-Berry (P-B) phase. This tunable chiral metasurface provides new ideas for the design of terahertz devices.