Anderson Localization at the Subwavelength Scale and Loss Compensation for Surface-Plasmon Polaritons in Disordered Arrays of Metallic Nanowires

TL;DR

This paper demonstrates that structural disorder in disordered arrays of metallic nanowires induces deep-subwavelength Anderson localization of surface-plasmon polaritons, with loss compensation achievable at low gain levels, advancing plasmonic nanostructure control.

Contribution

It provides a comprehensive 3D Maxwell equation analysis showing disorder-induced localization and loss compensation in plasmonic nanowires, a novel insight into subwavelength light trapping.

Findings

Disorder causes deep-subwavelength localization of SPPs.

Low optical gain suffices to compensate metal losses.

Localized modes are significantly smaller than the wavelength.

Abstract

Using a random array 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 3D 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 wavelength. Remarkably, the optical-gain coefficient, needed to compensate 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.