A dynamically reconfigurable terahertz metasurface enabled by hybrid Ge2Sb2Te5 and VO2 phase-change materials

Abstract

A multifunctional terahertz metasurface is proposed, which is designed based on temperature-controllable phase-change materials. Through the synergistic modulation of Ge₂Sb₂Te₅ (GST225) and vanadium dioxide (VO₂), the metasurface achieves linear-to-circular polarization conversion (LTC-PC), chiral response, focusing capability, and tunable broadband absorption functions. When GST225 is in the amorphous state and VO₂ is in the insulating state, the metasurface achieves efficient LTC-PC. Additionally, when illuminated with circularly polarized waves, the metasurface demonstrates strong circular dichroism (CD), and the corresponding CD efficiency is analyzed. The metasurface realizes focusing capability through the combined use of the Pancharatnam–Berry (PB) phase principle and resonant effects. When the GST225 material was tuned to the crystalline state, the dynamically tunable broadband absorption was achieved by modulating the conductivity of VO₂.