Nonlocal Response of the Plasmonic Nanowire Metamaterials

Nanowire metamaterials are a class of composite photonic media formed by an array of aligned plasmonic nanowires embedded in a dielectric matrix. Depending on exact composition, geometry, and excitation wavelength, nanowire structures are known to exhibit elliptical, hyperbolic, or epsilon-near-zero (ENZ) responses. In the ENZ regime optical response of the composite becomes strongly nonlocal. Excitation of an additional wave, caused by nonlocality, has been experimentally demonstrated in nanowire-based metamaterials. Here we present numerical and analytical studies of the nonlocal optical response of plasmonic nanowire metamaterials. Dispersion of photonic modes of plasmonic metamaterials has been studied in finite-element-method (FEM) simulations as a function of wavelength, geometry, and material parameters. Analytical description of nonlocal effective permittivity tensor has been developed. These analytical results are in agreement with FEM simulations and experimental data.