Multifunctional Reconfigurable Vanadium Dioxide Integrated Metasurface for Reflection, Asymmetric Transmission and Cross-Polarization Conversion in Terahertz Region

Integrating reconfigurable and diverse functionalities into a single metasurface at terahertz (THz) frequencies is an emerging research topic that faces significant challenges. Here, a reconfigurable THz metasurface is proposed, offering diversified functionalities based on the phase transition of vanadium dioxide (${\mathrm{VO}}_2$). The proposed metasurface can switch from wideband reflection to wideband cross-polarization conversion (CPC) and asymmetric transmission (AT) for linearly polarized waves. When ${\mathrm{VO}}_2$ is in its fully metallic state, the metasurface efficiently reflects normally incident waves ranging from 0.2 to 2.8 THz, with total reflection exceeding 0.8. When ${\mathrm{VO}}_2$ is in its insulating state, the metasurface achieves nearly perfect wideband cross-polarization conversion with CPC efficiency above 0.99 from 0.46 to 2.67 THz, and excellent AT effect with efficiency over 0.9 from 0.65 to 2.29 THz for normal incidence of linearly polarized waves. Moreover, the high efficiency of CPC and AT effects is maintained over a wide range of incident angles. The proposed switchable metasurface with diverse functionalities is expected to enable cutting-edge research and innovative applications in THz communication, sensing, and imaging.