Multifunctional Reflective Metasurface Based on a Pair of Exceptional Points

Exceptional points (EPs) are special singularities in non-Hermitian systems with degenerate eigenvalues and eigenstates, which exhibit various unique phenomena and enrich the mechanisms and functionalities of metasurfaces. Here, we propose a multifunctional reflective metasurface based on a pair of EPs. Due to the coalescent eigenvalues at the EP, the anisotropy and reciprocity meta-atom demonstrates asymmetric circular polarization (CP) wave control, which provides a novel approach for electromagnetic wave control. By combining a pair of EPs and Pancharatnam-Berry (PB) phase, we achieve precise phase control over two CP channels. As a proof of concept, the non-Hermitian metasurface array we proposed possesses both beaming focusing and RCS reduction capabilities under different CP waves incidence, which offers a new solution for the design of multifunctional metasurfaces.