Observation of Fundamental Spatial Limits of Light Localization

Disordered media such as photonic lattices and micro/nano-structures, bring light to localization in the spaces between the scattering sites that averages an optical mean free path. We have used scanning probe microscopy (with ~ 20 nm optical resolution) to collect localized light in the gaps between crystallographic defect scattering sites in III-V films with variety of defects densities. However, no localized light spot smaller than ~ 50 nm (corresponding to the mean free path smaller than ~14.5 nm) is observed in a large statistical distribution (observation at λ~390 nm). Experiment and simulation results to the first direct observation lowest spatial limit for optical Anderson localization at corresponding mean free path of ~13 nm for 390 nm wavelength.