Multipolar multifunction terahertz tunable metasurface

A terahertz coded metasurface composed of VO₂, polyimide, and Au is proposed. Based on line polarization multiplexing, seven functions in all are realized by designing the structure of the top VO₂ resonator and the middle gold pattern. The simulation results show that when VO₂ is metallic and the linearly polarized wave of f=1−2THz is vertically incident, the unit exhibits broadband absorption with an absorption rate (AR) greater than 84%. The AR in the range of 1.56–2 THz can reach more than 90%. When VO₂ is insulated, the unit can achieve narrowband absorption at 1.57 THz, with an AR of nearly 100%. Meanwhile, the same coded metasurface can realize one of the five functions of beam deflection, vortex beam, deflected vortex beam, beam splitting, and superimposed vortex beam under x and y polarization modes. This work can provide certain reference for the design of multifunctional devices with metamaterial in the terahertz field.