Theoretical investigation of a vanadium dioxide-based terahertz metasurface with maximum overlap bandwidth for polarization conversion and absorption

Abstract

In this paper, a wideband dual-functional terahertz (THz) metasurface based on VO₂ is proposed and theoretically investigated. By exploiting the phase-transition property of VO₂, the device dynamically switches between a wideband reflective cross-polarization converter and a wideband perfect absorber. The polarization conversion functionality is realized using a double-headed arrow resonator, while perfect absorption is achieved through a quad-square split-ring resonator configuration. The proposed metasurface exhibits a high polarization conversion ratio exceeding 95% over the frequency range of 1.09–5.59 THz, enabled by the superposition of multiple resonances at 1.68 THz, 2.69 THz, 4.18 THz, and 4.97 THz. In the absorption mode, the structure demonstrates absorption greater than 90% across a broad bandwidth from 2.15 to 6.64 THz, with prominent resonances at 2.62 THz and 5.91 THz. Notably, the device achieves a maximum overlapping bandwidth of 61.98% between the two functionalities, along with high angular stability up to 60°. Owing to its multifunctionality, wide spectral coverage, and robust angular performance, the proposed terahertz metasurface holds strong potential for applications in tunable terahertz filters, dynamic beam steering and wavefront control, and adaptive sensing and imaging systems.