Chiral metamaterial absorber with high selectivity for terahertz circular polarization waves

In this paper, a chiral metamaterial absorber (CMMA) is proposed for the realization of high selective absorption for right-handed and left-handed circular polarization (RCP and LCP) waves in the terahertz region. The CMMA is composed of a dielectric substrate sandwiched with a bi-layered fourfold twisted via-T-shaped (VTs) structure. The proposed CMMA has strong chiral-selective absorption bands, where absorption peaks for LCP and RCP occur at different resonance frequencies, finally resulting in a significant circular dichroism (CD) effect. The simulation results exhibit that absorption levels are greater than 90% and the maximal CD value is up to 42.2 dB at resonances. The mechanism of the chiral-selective absorption of the CMMA is illustrated and analyzed by surface current and power loss density distributions. Furthermore, the chiral-selective absorption properties can be effectively adjusted by changing the geometric parameters of the unit-cell of the proposed CMMA. Owing to its favorable performance, the proposed CMMA could be found in many potential applications in bolometric imaging, terahertz spectroscopic, detecting, and terahertz communications.