Non-Hermitian singularities in scattering spectra of Mie resonators.

Abstract

Non-Hermitian systems are known to have unique singularities, notably exceptional points. Mie resonators demonstrate fruitful electromagnetic multipole interference effects in scattering behavior. The research of these non-Hermitian singularities is typically conducted independently with the analysis of scattering interference. Here, we demonstrate fundamental relationships between non-Hermitian singularities and observe their manifestation in the scattering spectra. We reveal that exceptional points always exist in the anapole regime, and diabolic points are associated with superscattering. We confirm our theoretical findings in the microwave experiment by measuring the extinction spectra of subwavelength Mie-resonant ceramic rings. Our study underpins the generic behavior of non-Hermitian singularities in the scattering spectra of subwavelength Mie resonators, uncovering their special applications in non-Hermitian nonlinear optics and topological photonics.