Graphene-based switchable and tunable selective absorption metasurface

We propose a graphene-based switchable and tunable selective absorption metasurface. The metasurface is composed of a top layer of graphene symmetric semi-square ring (SSR), followed by a SiO2 dielectric layer, a layer of graphene dual symmetric semi-square rings (DSSRs) patterns, another SiO2 dielectric layer, and a gold reflective layer. The theoretical analysis of the designed metasurface was conducted using CST Microwave Studio. When operating in the x-polarized wave selective absorption (x-PWA) mode, the metasurface achieves absorption rates of 0.99 and 0.94 for x-polarized waves at 2.24 and 4.39 THz, respectively. During this mode, the absorption rates for y-polarized waves are 0.07 and 0.06, with LD values of −0.92 and −0.88. When switched to the y-polarized wave selective absorption (y-PWA) mode, the absorption rates for y-polarized waves at these frequencies are both 0.99, whereas for x-polarized waves, they are 0.06 and 0.07, with LD values of 0.93 and 0.92. Furthermore, by adjusting the Fermi level of graphene, the LD frequency can be dynamically tuned from 2.24 and 4.39 THz to 1.80 and 3.46 THz, respectively. The metasurface also demonstrates robust performance at an incidence angle of 60 deg. Finally, the designed unit, along with its rotated counterpart, enables flexible near-field imaging capabilities through its distinct absorption modes.