VO 2 -based chiral trifunctional tunable metasurface for near- and mid-infrared bands

This work presents a trifunctional tunable metasurface with circular dichroism (CD) effect. It aims to overcome the common limitations of conventional metasurfaces, such as single functionality, narrow operating bandwidths, and low CD values. The proposed metasurface adopts a vanadium dioxide (VO 2 )-metal structure. Under circularly polarized light incidence, the metasurface exhibits a strong broadband CD effect, achieving CD values exceeding 0.80 in 1095–2046 nm, with a peak value of ∼0.93 at 1689 nm, while realizing circular-to-circular polarization conversion in 989–2124 nm. Under linearly polarized light incidence, linear-to-circular polarization conversion is realized in 922–2335 nm. The intensity of each function can be modulated by adjusting the temperature. This work promotes the development of near- and mid-infrared devices, such as CD supermirrors and optical communication systems.