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 °C and 72 °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° for temperatures below 60 °C, 67.6° for temperatures ranging from 60 °C to 72 °C, and 27.5° for temperatures exceeding 72 °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.