Resonant absorption in an inhomogeneous disordered metamaterial: First-principles simulation
Abstract
In this study, we perform first-principles simulations of the resonant excitation of plasma-like oscillations in a two-dimensional inhomogeneous disordered metamaterial. The oscillations are initiated by an oblique incidence of a linearly polarized electromagnetic wave. The conditions for resonant excitation are satisfied near the point where the real part of the effective permittivity of the metamaterial changes sign from positive to negative and crosses zero. First, the problem was analyzed in the framework of the effective medium approximation, which predicts a resonant growth of the electric field and associated resonant absorption near the interface between positive and negative permittivity. It was shown that an array of point dipoles can sustain plasma-like waves near the zero of the effective permittivity. In order to trace the appearance of such a mode at the microscopic scale, full-scale first-principles simulations of a two-dimensional metamaterial with a randomly generated distribution and a linearly increasing average concentration of meta-atoms were performed. The results of the simulations were compared to the predictions of the effective medium approximation. The influence of the fluctuations in the meta-atom concentration on the excitation of the field oscillations and the resonant absorption was quantified.
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