A Bidirectional Controllable Terahertz Multifunctional Device Based on Graphene-Vanadium Dioxide

A bidirectional controllable terahertz multifunctional device based on graphene and vanadium dioxide is proposed in this paper. By adjusting the phase transition characteristics of vanadium dioxide and the chemical potential of graphene, the bidirectional transmission of electromagnetic waves is regulated to achieve multiple functions. When vanadium dioxide is in its metallic state, the device exhibits circular dichroism at 5.65 THz for the forward left- and right-circularly polarized waves. For the backward-propagating electromagnetic waves, when the chemical potential of graphene is 1 eV and 0 eV, the device shows broadband absorption and broadband orthogonal polarization conversion, respectively. The relative bandwidths are 101.1% and 126.3%, respectively. When vanadium dioxide is in its insulating state, the device exhibits an obvious asymmetric transmission effect on left- and right-circularly polarized light at 1.66 THz and 3.1 THz. The proposed metasurface is expected to expand the application of terahertz technology and has broad prospects in the fields of 6G mobile communication, high-capacity information processing, environmental and food detection.