Reconfigurable terahertz metasurface and dynamic vortex beam manipulation based on the phase transition characteristics of VO2

To overcome the technical limitations of static operational frameworks in conventional metasurfaces, this paper introduces a novel platform demonstrating dynamic reconfigurability utilizing the phase-transition properties of vanadium dioxide (VO₂). By designing an Au–VO₂ composite split-ring resonator (SRR), a temperature-responsive mechanism for dynamic topological charge control is established. Leveraging the insulator-to-metal (ITM) phase transition characteristics of VO₂, the transmission phase response of the metasurface unit can be finely tuned through precise temperature regulation. After structural parameter optimization and the application of a rotation strategy based on the Pancharatnam–Berry (PB) phase principle, the constructed periodic array structure achieves reversible switching between topological charges of ±1 and ±2 within the atmospheric window of 0.62–0.68 THz. Numerical simulations demonstrate that orbital angular momentum (OAM) vortex beams generated at distinct temperatures (293 K and 341 K) maintain stable main-lobe intensity distributions, confirming notable mode independence. Significantly, the reconfigured transmission phase response exhibits temperature-independent characteristics, realizing dynamically reconfigurable unit phase states. This research prevents an innovative solution for dynamic optical field control in the Terahertz (THz) band and offers valuable insights for advanced applications.