Broadband tunable chiral selective metamaterial absorber using vanadium dioxide

This paper proposes a tunable chiral selective metamaterial absorber based on a composite structure of S-shaped metal resonator and vanadium dioxide (VO2) micro-rod for broadband circular polarization-selective absorption and dynamic modulation in the terahertz (THz) regime. The asymmetric geometric design breaks mirror symmetry, achieving over 85% absorption for right-handed circularly polarized waves in the 0.675–1.244 THz while maintaining below 15% absorption for left-handed circularly polarized waves in the 1–2 THz. The metamaterial exhibits remarkable circular dichroism (CD) up to 80% within 0.99–1.74 THz, with a relative bandwidth of 54.9%. Leveraging the insulator-to-metal transition of VO2, a CD modulation depth of 0.7 is achieved in the 0.99–1.74 THz. Theoretical analysis reveals that the selective absorption originates from excitation of plasmon polariton modes in the micro-rod. This reconfigurable design enables unprecedented THz polarization control, with promising applications in chiral molecular detection and polarization imaging systems.