Theoretical seminar | 10 June 2026

Subwavelength dielectric Mie resonators constitute a minimal yet powerful platform for exploring non-Hermitian photonics, where radiative losses render the eigenvalue spectrum intrinsically complex. We first demonstrate that individual high-index Mie resonators can host exceptional points (EPs) originating from the interference of multipolar modes coupled to the same radiation channel. By continuously tuning geometric parameters, these EPs are shown to be connected by a bulk Fermi arc, revealing a two-sheeted Riemann surface in the complex frequency plane and establishing a direct link between non-Hermitian topology and single-particle scattering physics [1,2].

Building on this single-resonator paradigm, was extended the concept to periodic and stacked dielectric metasurfaces, where collective-mode hybridization enables the controlled merging of bound states in the continuum (BICs) into exceptional bound states in the continuum (EP-BICs) [3]. These states inherit the nonradiative character of BICs together with the singular dispersion and enhanced parametric sensitivity of EPs, thereby overcoming the fundamental radiative-loss limitations of nanoscale non-Hermitian systems.

Finally, was demonstrated that the extreme field confinement and tailored dissipation landscape in EP and EP-BIC platforms provide a fertile ground for nonlinear and multistable optical responses [4].

Main paper/arXiv, related to the seminar, and other references, up to 5
[1] F. Zhang, N. S. Solodovchenko, H. Fan, et al., “Non-Hermitian singularities in scattering spectra of Mie resonators,” Sci. Adv. 11, eadr9183 (2025).
[2] N. Solodovchenko, F. Zhang, M. Bochkarev, et al., “Experimental observation of bulk Fermi arc in a single dielectric resonator,” arXiv 2502.12711 (2026).
[3] A. Canós Valero, Z. Sztranyovszky, E. A. Muljarov, A. Bogdanov, and T. Weiss, “Exceptional bound states in the continuum,” Phys. Rev. Lett. 134, 103802 (2025).
[4] Z. Liu, X. Yin, A. Bogdanov, et al., “Optical multistability in a compact microcavity enabled by near-exceptional coupling,” Nat. Nanotechnology (2026).