Motivated by topologically protected states in wave physics, we study localized eigenmodes
in one-dimensional periodic media with defects. The Su–Schrieffer–Heeger model (the …

We present the mathematical theory of one-dimensional infinitely periodic chains of
subwavelength resonators. We analyze both Hermitian and non-Hermitian systems …

Robustly manipulating waves on subwavelength scales can be achieved by, first, designing
a structure with a subwavelength band gap and, second, introducing a defect so that …

When sources of energy gain and loss are introduced to a wave scattering system, the
underlying mathematical formulation will be non-Hermitian. This paves the way for the …

We show that defect modes in infinite systems of resonators have corresponding modes in
finite systems which converge as the size of the system increases. We study the generalized …

The aim of this paper is fourfold:(i) to obtain explicit formulas for the eigenpairs of perturbed
tridiagonal block Toeplitz matrices;(ii) to make use of such formulas in order to provide a …

We solve the wave equation with periodically time-modulated material parameters in a one-
dimensional high-contrast resonator structure in the subwavelength regime exactly, for …

We prove the possibility of achieving unidirectional edge modes in time-modulated supercell
structures. Such finite structures consist of two trimers repeated periodically. Because of their …

We show the possibility of achieving nonreciprocal wave propagation in space-time
modulated media and give an asymptotic analysis of the nonreciprocity property in terms of …

Our aim in this paper is twofold. Firstly, we develop a new asymptotic theory for Floquet
exponents. We consider a linear system of differential equations with a time-periodic …