An Ultra-Broadband and Multi-Frequency Switchable Terahertz Absorber Based on Patterned VO2 Multilayer Stacked Architecture

Abstract

This study designed a multilayer stacked ultra-broadband and multifrequency switchable terahertz absorber employing vanadium dioxide (VO₂), polydimethylsiloxane (PDMS) and embedded Aurum (Au). This absorber achieves reversible phase transitions in VO₂ through temperature control, consequently altering its electrical conductivity to switch absorption characteristics. Based on impedance matching theory and simulations of electric field and current distribution, the physical mechanism enabling ultra-broadband and multi-frequency switching in this VO₂ switchable terahertz absorber is elucidated. Simulation results demonstrate that the absorber realizes ultra-broadband absorption, exhibiting a bandwidth of 6.36 THz spanning from 6.47 THz to 12.83 THz at a metallic-phase conductivity of 80000 S/m for VO₂ . By contrast, an insulating-phase conductivity of 150 S/m for VO₂ enables the absorber to exhibit pronounced multi-frequency absorption properties, where six strong absorption peaks with absorption rates over 90 % are observed, corresponding to the absorption frequency points of 3.26 THz, 6.68 THz, 7.69 THz, 9.26 THz, 10.32 THz and 13.09 THz, respectively. Furthermore, by employing a symmetrical structural design, this absorber exhibits outstanding polarization stability and retains highly efficient absorption across a broad range of incident angles spanning 0° to 60°. Therefore, this absorber demonstrates tremendous prospects in cutting-edge fields such as terahertz imaging, terahertz modulation, and material inspection.