Vanadium dioxide-assisted switchable broadband terahertz metasurface for polarization conversion and phase modulation

Abstract Switchable metasurfaces with diversified functionalities have become an emerging research area owing to its potential for realizing integrated and miniature meta-devices. Although great efforts have been devoted in this area, switchable metasurfaces with diversified functionalities still require dealing with formidable challenges. In this paper, a switchable broadband terahertz (THz) metasurface with multiple functionalities is proposed utilizing the phase transition property of vanadium dioxide (VO 2 ), and it can switch functionalities by changing the state of VO 2 from metal to insulator thermally. The simulation results demonstrate that when VO 2 is in metallic state at the temperature of 400 K, the designed metasurface works as a half wave plane with polarization conversion ratio more than 90% at THz frequency band ranging from 0.66 to 1.44 THz. When VO 2 is in insulating state at the temperature of 300 K, the metasurface can flexibly control the phase of the THz wave. As a proof of concept, several devices with high performance for realizing anomalous reflection, diffuse scattering, vortex beam and beam-focusing are numerically investigated. The proposed metasurface has potential applications in THz imaging, sensing and other intellectual systems for photonics integration.