Chiral Metasurfaces with Maximum Circular Dichroism Enabled by Out‐of‐Plane Plasmonic System

Abstract Chiral metasurfaces with pronounced reflective chiroptical responses have drawn extensive attention as they can offer great opportunities for various chirality‐related applications. However, their fascinating potential are restrained by limited chiroptical responses, relatively complex design principle, and fabrication strategy. Herein, a concise and general design principle to develop out‐of‐plane reflective chiral metasurfaces, empowered with the maximum theoretical circular dichroism (CD), is theoretically proposed and experimentally demonstrated. The designed out‐of‐plane chiral metasurfaces operating in the terahertz (THz) region are flexibly fabricated via a simple, scalable, low‐cost and lithography‐free fabrication strategy by integrating a three‐dimensional (3D) printing technique. Finally, the methodological stabilities and the strong chiroptical responses of proposed chiral metasurfaces are validated experimentally. From the general design principle, simple fabrication strategy as well as maximum chiroptical responses of proposed reflective chiral metasurfaces, it can be envisaged that these findings may overcome the difficulties in design, optimization, and fabrication for reflective chiral metasurfaces and provide promising potentials for various chirality‐related applications in emerging THz technologies, such as chiral sensing, imaging, spectroscopy and polarimetry.