Multifunctional reconfigurable terahertz metasurface based on vanadium dioxide phase transition: achieving broadband...

This study introduces a reconfigurable terahertz metasurface that enables ultra-wideband absorption and cross-polarization conversion through the phase transition of vanadium dioxide (VO₂). In the metallic phase, VO₂ operates as a broadband absorber, attaining an impressive absorption efficiency with a relative bandwidth of up to 97.6% throughout the 3.25-9.45 THz frequency range, while sustaining a high absorption rate across an incidence angle spectrum of 0°-60°. Upon VO₂'s transition to the insulating state, the device becomes a highly efficient polarization converter functioning within the 3.17-9.02 THz range, consistently achieving a polarization conversion ratio (PCR) over 90% for both x- and y-polarized incident waves. This design guarantees ultra-wideband performance in both operational modes, exhibiting remarkable polarization insensitivity and wide-angle stability; additionally, the absorption efficiency may be continuously and dynamically adjusted based on the extent of VO₂ phase transition. The engineered switchable device possesses extensive application potential in terahertz dynamic stealth, high-speed communication, and high-contrast polarization imaging.