Localized surface-plasmon polaritons in disordered nanostructured metal surfaces: Shape versus Anderson-localized resonances

Abstract

The electromagnetic wave scattering from disordered nanostructured metal surfaces supporting surface-plasmon polaritons (SPP) is studied by means of fully retarded scattering formulations. We investigate the two physical mechanisms which may underlie the excitation of localized SPP: Anderson localization and shape resonances. The former mechanism is discarded since plane-wave excited, localized SPP are observed in the absence of proper Anderson localization of SPP. In contrast, a detailed analysis of the near field for various ensembles of surface realizations permits us to identify SPP shape resonances typically occurring at sub-100-nm grooves or ridges, the latter being significantly stronger. © 2003 The American Physical Society.