Anderson localization at the subwavelength scale for surface plasmon polaritons in disordered arrays of metallic nanowires

Using one- and two-dimensional random arrays of coupled metallic nanowires as a generic example of disordered plasmonic systems, we demonstrate that the structural disorder induces localization of light in these nanostructures at a deep-subwavelength scale. The ab initio analysis is based on solving the complete set of three-dimensional Maxwell equations. We find that random variations of the radius of coupled plasmonic nanowires are sufficient to induce the Anderson localization (AL) of surface plasmon polaritons (SPPs), the size of these trapped modes being significantly smaller than the optical wavelength. Remarkably, the optical-gain coefficient, needed to compensate for losses in the plasmonic components of the system, is much smaller than the loss coefficient of the metal, which is obviously beneficial for the realization of the AL in plasmonic nanostructures. The dynamics of excitation and propagation of the Anderson-localized SPPs are addressed too.