Dynamically reconfigurable VO2-based metamaterial absorber with an ultra-broad 11-THz absorption bandwidth

Abstract

A dynamically reconfigurable, polarization-insensitive terahertz (THz) metamaterial absorber based on phase-change vanadium dioxide (VO2) is proposed and numerically investigated by full-wave simulations (CST Studio Suite). The absorber adopts a simple three-layer configuration: a patterned VO2 resonant layer, a Topas dielectric spacer, and a continuous Au ground plane. VO2 is chosen because its reversible insulator-to-metal transition near 68 °C changes the conductivity by about three orders of magnitude, enabling continuous, geometry-independent tuning of the absorption. In the metallic state, the patterned VO2 layer behaves as a lossy resonant meta-layer: its moderate conductivity supplies the ohmic loss required for near-perfect impedance matching, while the multiple closely spaced resonances of the four sector-shaped elements overlap, merging into a continuous absorption window exceeding 90% from 6.55 to 17.55 THz (absolute bandwidth 11 THz, relative bandwidth 91.3%). By tuning the conductivity of VO2 from 200 to 2 × 105 S/m, the absorption can be continuously modulated from 2.33% to 99.96%, and the rotationally symmetric geometry ensures polarization-insensitive, wide-angle absorption (stable up to 50°). Owing to its ultrabroadband absorption, wide tuning range, polarization insensitivity, and wide-angle stability, the proposed absorber is expected to serve as a promising platform for prospective THz applications, such as electromagnetic shielding, modulation, and sensing.