Lossy-Inspired Metasurface for Observing Exceptional Points in Microwave Band

Exceptional points (EPs), the degeneracies of eigenvalues and eigenvectors in non-Hermitian systems, possess versatile intriguing properties. However, most of the studies on non-Hermitian metasurfaces conducted to date are concentrated within the terahertz and visible wavelength bands. In these regimes, surface plasmon polaritons can be excited at the interface between metal and dielectric, enabling the intuitive observation and manipulation of EPs. Here, in order to conduct such potential EP performance in microwave region, a meta-atom, consisting of nickel-plated split-ring and copper-plated I-shaped resonators, is designed. The underlying principle is inspired by loss mechanism, which is introduced through the excellent electrical conductivity of copper with low ohmic losses and the significant ferromagnetic qualities of nickel. The desired EP resonance is observed with abrupt phase transitions, eigenvalue degeneracy, and asymmetric transmission of circularly polarized waves in varying different parameter spaces. These results can provide a new paradigm for chirality detection, asymmetry transformations, and so forth.