Strong circular dichroism absorbers using chiral metamaterials with circular polarization

Abstract

We designed and characterized a chiral metamaterial circularly polarized strong circular dichroism absorber with dynamic tuning capabilities using graphene. The synergistic combination of strong circular dichroism and perfect absorption, coupled with the tunability afforded by graphene, positions this absorber as a promising candidate for advanced electromagnetic applications. Employing a frequency-domain solver in electromagnetic simulation software, the impact of parameters such as the thickness of a metal U-ring, a silica dielectric layer, and the polarization angle of incident light on circular dichroism is systematically analyzed. Strong circular dichroism can be achieved by adjusting the misalignment angle of the metal U-ring, reaching a value as high as 0.91. At an incident angle of 60°, left-circularly polarized (LCP) light demonstrates outstanding wide-angle absorption performance, absorbing over 80% in the x-z plane and more than 70% in the y-z plane. Transitioning from circular to linear polarization and changing the tilt angle of the metal U-ring also achieves a 99.99% absorption peak at 1.33 THz. Moreover, in comparison to conventional absorbers, the structure presented in this study offers enhanced controllability of absorption performance through external voltage manipulation. This research not only refines the existing concepts but also introduces novel ideas for the development of tunable chiral optical devices.