Enhanced Second-Harmonic Generation by Metal Surfaces with Nanoscale Roughness: Nanoscale Dephasing, Depolarization, and Correlations

The topography, polarization and spatial-coherence properties of the second-harmonic (SH) local fields at rough metal surfaces are discussed. It is found that the spatial distributions of the SH local fields and fundamental frequency are very different with highly enhanced hot spots of the SH. The spatial correlation functions of the phase, amplitude and direction of the SH polarization all show spatial decay on the nanoscale. Results show that SH radiation collected from even nanometer-scale areas has the nature of hyper-Rayleigh scattering.