Asymmetric transmission in bilayer chiral metasurfaces for both linearly and circularly polarized waves

In this paper, we numerically and theoretically propose an architecture with bilayer chiral metasurfaces which can achieve asymmetric transmission (AT) for both linearly and circularly polarized waves in the near-infrared region. The research results show that the structure can obtain a maximum AT ∼ 0.65 and polarization conversion ratio over 80% for linearly polarized waves. In addition, dual-band AT can even be achieved for circularly polarized waves. The electric field distribution and current vector are presented to explain the physical mechanisms of the AT effects. Our research work may have some potential applications in designing optical diode devices, such as asymmetric wave splitters, polarizers, rotators, etc.