Liquid-crystal-loaded chiral metasurfaces for reconfigurable multiband spin-selective light absorption.

Light absorption plays a key role in numerous photonic devices. In this work, we theoretically demonstrate that multiband circularly polarized light can be spin-selectively absorbed with a single-layered metasurface. The difference of absorption efficiency between left- and right-handed circularly polarized light can reach 40%. This giant chiroptical effect originates from different plasmonic resonances induced by the incident circularly polarized light with opposite spin states. Furthermore, by integrating the metasurface with nematic liquid crystals, the spin-selective absorption and the chirality can be dynamically reconfigured via applying a bias voltage. The advantageous features of being multiband-absorptive, backplane-free and reconfigurable make our proposed liquid-crystal-loaded chiral metasurfaces potentially useful for various photonic applications.