Graphene-Based Triple-Band Tunable Metasurface With Strong Circular Dichroism for THz Communication

Abstract

Light absorption based on chiral metasurfaces in the terahertz (THz) region has garnered considerable attention as a prominent research focus, finding extensive applications in biological monitoring, analytical chemistry, plasmonic sensing, and communication. This letter introduces a graphene-enabled triple-band tunable chiral metasurface absorber demonstrating highly selective absorption for right-handed and left-handed circularly polarized light in the THz region. Particularly noteworthy is the substantial discrepancy in absorption efficiency observed under normal and oblique incidence, which is maximized under oblique incidence. This pronounced chiroptical effect arises from distinct plasmonic resonances induced by incident circularly polarized light with opposite spin states. Moreover, the circular dichroism (CD) strengths can be dynamically adjusted by modulating the chemical potential of graphene. Analyses involving electric field distribution and current distributions have been employed to elucidate the mechanism underlying spin-selective absorption. The proposed tunable chiral metasurface absorber features a straightforward and compact design, offering immense potential for various applications within the terahertz bands.