In this Review, the theory and applications of optical micro‐and nano‐resonators are
presented from the underlying concept of their natural resonances, the so‐called quasi …

The scattering of electromagnetic waves by resonant systems is determined by the excitation
of the quasinormal modes (QNMs), ie the eigenmodes, of the system. This Review …

The specificity of modal-expansion formalisms is their capabilities to model the physical
properties in the natural resonance-state basis of the system in question, leading to a …

We present a biorthogonal approach for modeling the response of localized electromagnetic
resonators using quasinormal modes, which represent the natural, dissipative eigenmodes …

Nanophotonic chiral sensing has recently attracted a lot of attention. The idea is to exploit
the strong light–matter interaction in nanophotonic resonators to determine the …

Optical resonators are widely used in modern photonics. Their spectral response and
temporal dynamics are fundamentally driven by their natural resonances, the so-called …

All electromagnetic systems, in particular resonators or antennas, have resonances with
finite lifetimes. The associated eigenstates, also called quasinormal modes, are essentially …

A novel theoretical non-Hermitian formalism for analyzing nonlinear nano-optics is
proposed. Its main strength lies in the unique way it analytically incorporates the …

Resonances are essential for understanding the interactions between light and matter in
photonic systems. The real frequency response of the non-Hermitian systems depends on …

We present a quasinormal-mode (QNM) theory for coupled loss and gain resonators
working in the vicinity of an exceptional point. Assuming linear media, which can be fully …