A transmission-type terahertz beam reconfigurable metasurface based on a multilayer annular structure

To achieve flexible control over terahertz beams, vanadium dioxide (VO2) with phase transition temperatures of 60 degrees C and 72 degrees C is selected. The effects of VO2 in its two states-insulator (before phase transition) and metallic (after phase transition)-on the amplitude and phase of the unit structure are analyzed. A terahertz beam reconfigurable phase gradient metasurface based on VO2 with different phase transition temperatures is designed. By adjusting the surrounding temperature, the metasurface demonstrated the capability to produce distinct beam deflection angles corresponding to different thermal conditions. Specifically, at a frequency of 1.35 THz, the beam deflection angle was measured at 0 degrees for temperatures below 60 degrees C, 67.6 degrees for temperatures ranging from 60 degrees C to 72 degrees C, and 27.5 degrees for temperatures exceeding 72 degrees C. This VO2-based terahertz phase gradient metasurface with different phase transition temperatures provides a novel approach for the flexible control of terahertz beams, showing significant potential applications in terahertz transmission, imaging, and wireless communication.