Waveguide regimes in a pair of optically coupled non-Hermitian subwavelength structures

This work is devoted to studying the efficiency of excitation and support of waveguide modes for a non-Hermitian optical system consisting of two thin optically coupled subwavelength periodic structures. Excitation modes of various modes were studied depending on the angle of incidence of the exciting field for the visible and near-IR ranges for TE and TM polarizations. The possibilities of excitation of single-mode regimes with high field localization in thin subwavelength structures, as well as regime of hybridization modes, have been studied. The excitation modes of the unidirectional waveguide mode, when linearly polarized light (TM) is incident on an optically coupled system of two subwavelength periodic structures, have been separately studied. We analyzed the Q-factors for various permittivity modulation profiles, as well as the features of the eigenstates of the system under consideration, and studied the behavior of the system near exceptional points, which can be effectively used to control the switching of waveguide modes. Research was carried out, in particular, for AlGaAs/GaAs lattices, for which a decrease in the thickness of the active region leads to a decrease in the optical confinement factor and a decrease in the lasing threshold.