Broadband and strength-switchable circular dichroism in a Ge2Sb2Te5-based metasurface

Circular dichroism (CD) is highly required in the applications of biological detection and analytical chemistry. In this paper, we achieved a giant, broadband, and strength-switchable CD effect in a quadruple z-shaped Ge2Sb2Te5 (GST) metasurface. At the amorphous state of GST (a-GST), the giant CD reaches 0.92 and the width of the absorption >0.80 is about 100 nm. The giant and broadb and CD originates from polarization selective excitations of Mie resonances and the coupling between subunit resonators. With the transition from a-GST to crystalline GST, CD could be dynamically switched from 0.92 to 0.05. The GST-based metasurfaces with giant and wide-range switching CD will promote the development of active chiral devices. (c) 2023 Optica Publishing Group

Automated summary

This paper presents a giant, broadband, and strength-switchable CD effect achieved in a quadruple z-shaped GST metasurface. The CD can be dynamically switched from 0.92 to 0.05 with the transition from amorphous GST to crystalline GST, offering potential for the development of active chiral devices.