The novel graphene metasurfaces based on split-ring resonators for tunable polarization switching and beam steering at terahertz frequencies

Graphene-based metasurfaces have emerged as promising photoelectric devices for dynamically controlling the polarization and wavefront of electromagnetic waves. A series of novel graphene-based metasurfaces consisting of split-ring resonators are proposed and researched. A dynamically tunable broadband converter of polarization states composed of periodically patterned graphene split-rings for linearly polarized waves is achieved in terahertz regime. By designing different geometrical parameters, the resonators indicate 2 pi of smooth phase modulation in a broadband frequency regime. Based on the phase profile design, a polarization beam splitter and a transmission-type focusing metasurface in a broadband frequency regime are both demonstrated successfully. Furthermore, the efficiency of these metasurfaces is dynamically tunable by modulating the gate voltage to change the Fermi energy (E-f) of graphene. This work may offer a potentially effective method to instruct the design of tunable polarization converter and wavefront-controlling devices. (C) 2019 Elsevier Ltd. All rights reserved.