Switchable Bifunctional Chiral Metasurface Based on Vanadium Dioxide for Terahertz Waves

A switchable chiral metasurface (CM) with high polarization conversion ratio (PCR) and absorptivity based on vanadium dioxide (VO 2 ) is proposed and numerically demonstrated in the terahertz (THz) regime. The proposed design consists of VO 2 –Au‐mixed resonant pattern layer, Si dielectric layer, and Au ground plate, which can achieve tunable bifunctional linear polarization conversion (LPC) and absorption (ABS) by varying the conductivity of VO 2 (). For = 10 S m −1 , the designed CM possesses a function of broadband LPC. More than 90% PCR is obtained in 1.79–2.46 THz, and the corresponding relative bandwidth (RBW) is 31.28%. For = 2 × 10 5 S m −1 , the designed CM can efficiently absorb incident electromagnetic (EM) waves in 1.54–2.76 THz with the absorptivity exceeding 90% (RBW = 56.47%). The mechanisms of LPC and ABS are analyzed. The effects of geometric and EM parameters, incident angle, and polarization angle on its bifunctional characteristics are also studied. The LPC and ABS performances are maintained within a certain range of incident angles. Furthermore, the proposed CM exhibits polarization insensitivity. The developed switchable bifunctional CM has great potential application value in advanced THz research and smart device.