Tunable multispectral chiral effects of folded S-shaped metamaterials in mid-infrared region

Abstract

Three-dimensional chiral optical metamaterials have attracted tremendous interests due to their enhanced chiroptical responses. Here we report an S-shape based folded metamaterial which can realize the tunable chiroptical property of multispectral effects in the mid-infrared region. This folded S-shaped metamaterial exhibits distinctive chiroptical responses under the irradiation of circularly polarized light with different spin states and it achieves two strong circular dichroism signals at 5μm and 7.9μm, respectively. We attribute the spin-selective chiroptical characteristic to the intrinsic mechanism of the parallel and antiparallel coupling modes between induced electric dipoles and magnetic dipoles. Moreover, we also demonstrate that the chiroptical response is easily regulated by tuning its structural parameters. These properties promise various strong application potentials, such as spin-selective optical wavelength multiplexing, circularly polarized spectral filters, and ultrasensitive chiral sensors.