Chirality-driven metasurface for enhanced circular dichroism and perfect absorption: modeling and design

Abstract In this study a chiral metasurface based on three concentric asymmetrical semicircular rings (SCRs) made of gold is presented. Analysis shows that the number of SCRs extensively affects the value of circular dichroism (CD). Perfect absorption and a large CD covering the S and C bands is achieved. The bandwidth and the peak value of CD are tuned by varying the heights of the SCRs and their orientation angle, leading to strong Fano resonance. The structure also exhibits wide angular stability. Furthermore, a 4 × 4 periodic array of this metasurface is designed for dynamic modulation of the imaging state over the S and C bands for potential applications in optical communication encryption.