Transition of localization of light to delocalization outside the disordered medium.*

We have studied the evolution of localized light by probe microscopy (at second harmonic regime: λ~390 nm) created by disordered medium made of threading dislocations in GaAs thin films. Details of localized light was monitored from surface of the sample (~15 nm from sample) up to ~20 μm away from sample. Second harmonic optical probe microscopy information is shielded from the dominant surface fundamental reflection, providing undisturbed details of light localization transition and dispersion at deep subwavelength (with ~ 20 nm optical resolution). We observed that light becomes delocalized around ~12 μm away from surface of the sample where Anderson localization statistical signatures changes.