Surface plasmon polariton phase retrieval via nanoscale surface roughness induced cross-polarization scattering

Abstract

This article demonstrates an elegant method for experimental retrieval of the buried phase information of optical phenomena at metallic-dielectric interfaces, especially surface plasmon polaritons (SPP), employing a model explicitly based on roughness-induced cross-polarization scattering. This inherent roughness of the interfaces within typical SPP Attenuated Total Reflection (ATR) setups leads to two interlinked phenomena: Angular broadening and cross-polarization scattering. The microscopic interface features generate altered polarization vectors which are comparably weak but, because of their orthogonal polarization direction, appreciable within the specularly reflected light. The information contained in this s-polarized light enables us to retrieve the phase information of SPPs through the interference model of cross-polarization scattering described here. On that basis, this article demonstrates the retrieval of phase shifts for multiple silver thicknesses of SPPs generated within an ATR geometry. Additionally, the method permits the evaluation of surface roughness parameters, characterization of the angular broadening of reflection, and determination of the thicknesses of the metallic layers.