Strong photon-magnetoexciton coupling in quantum metamaterials: Nonlocal homogenization approach

We have studied a quantum metamaterial composed of a dielectric slab and a nonlocal semiconductor slab containing a quantum well, which serves as a source of magnetoexcitons under an external dc magnetic field. The analysis is based on an extended nonlocal homogenization theory that accounts for both the structural nonlocality of periodic medium and the quantum nonlocality of confined magnetoexcitons. This approach allows us to calculate the dispersion relations and the nonlocal effective permittivity, revealing the characteristics of Bloch photonic modes and the spectral positions of magnetoexciton resonances. The results are shown to be crucial for optimizing the design of finite photonic crystals and for adequately identifying the origin of strong coupling features in the optical spectra. The optical response of nine periods of dielectric semiconductor bilayer, embedded between two high-index leads, is studied as a function of the incidence angle θ which selects Fabry–Perot modes with distinct field localization and radiative leakage into the leads. For small θ values, where the fields remain propagating inside the dielectric slabs, the excitation of Fabry–Perot modes results in a Rabi splitting of about 4.5 meV. At greater θ, where the fields in the dielectric slabs become evanescent, two consecutive Fabry–Perot modes simultaneously couple to two magnetoexciton resonances, leading to distinct splittings of 7.5 and 7.2 meV. Such simultaneous dual-mode coupling, achieved in a low-loss dielectric-semiconductor configuration, contrasts with previous systems where strong coupling typically involves only one photonic mode and a single magnetoexcitonic level. Our findings demonstrate the potential of considered setup for developing the tunable polaritonic devices.