Design of a dual-function infrared polarization controller based on a dynamically tunable metasurface of vanadium dioxide

This study presents a dynamically tunable metasurface device that exploits the thermally induced phase transition properties of vanadium dioxide (VO 2 ) to achieve dual-functionality in the infrared regime. The proposed structure features a multilayer configuration consisting of (i) an L-shaped silver nanoantenna and a ring-shaped VO 2 resonator as the top layer, (ii) a silicon dioxide (SiO 2 ) dielectric spacer, and (iii) a silver reflective substrate. Numerical simulations demonstrate that in the insulating phase (333 K), the device operates as a broadband cross-polarization converter, exhibiting a polarization conversion ratio (PCR) up to 0.99 across 1414-3127 nm. Conversely, when VO 2 transitions to its metallic state (361 K), the structure functions as a near-perfect absorber, achieving an absorption efficiency exceeding 0.96% over a broad spectral range (1026-3806 nm). Surface current analysis and impedance matching theory reveal that the polarization conversion mechanism arises from coupled electric and magnetic dipole resonances, while the absorption behavior stems from synergistic interactions among localized surface plasmon resonance (LSPR), propagating surface plasmon resonance (PSPR), and Fabry-Pérot (F-P) cavity effects. Furthermore, parametric studies investigate the impact of structural geometry, incident angle, and polarization state on device performance. Owing to its simple architecture, dynamic tunability, and high efficiency, this design offers a promising approach for reconfigurable integrated photonic systems.