Statistical Nonlinear Optical Mapping of Localized and Delocalized Plasmonic Modes in Disordered Gold Metasurfaces
Résumé
Using a statistical analysis of nonlinear luminescence images measured with randomly wavefront-shaped femtosecond excitations, we provide direct insight on both the localized and delocalized plasmonic modes featured by disordered gold metasurfaces. We can image independently areas where far-field wavefront shaping can control the optical properties, and areas with strong subwavelength optical hotspots. In practice, the fraction of the disordered plasmonic surface on which wavefront control is feasible depends strongly on the nanoscale morphology of the sample. Close to the percolation threshold, the entire surface is sensitive to wavefront shaping and we observe the largest densities of delocalized modes as well as the strongest optical hotspots. These results demonstrate how statistical imaging schemes can offset the complexity of disordered nanophotonic systems in order to characterize their optical properties.
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