The Optical Chiral Properties of Double-Layer T-Shaped Plasmonic Array

Nanostructures with chiral features have a wide range of applications in circular polarizers, optical modulators, and optoelectronic devices. In this study, we designed a three-dimensional bilayer T-shaped chiral structure to investigate the circular dichroism of multilayer nanostructures. We simulated the designed chiral structure and results that showed the maximum circular dichroism value occurred when the lower layer T-shaped structure rotated to 40°. The spectral response of the proposed structure can be considered as a coupling between upper and lower resonances, and the mechanism of optical chirality is explored by simulating the internal current distribution in metal. The model revealed that different current oscillations were excited by incident light in the upper and lower layers. Our results provide insightful references for analyzing the physical mechanism of circular dichroism signals and improving the circular dichroism signals of metasurfaces.