  In disordered media light can be localized in the spaces between scattering
sites which average to an optical mean free path (MFP). However the fundamental
question of the smallest MFP that can support Anderson localization of light
remains unanswered due to fabrication complexity of a scattering medium with
controlled nano-scale gaps and lack of required resolution by far-field
methods. Here we use scanning probe microscopy technique to collect localized
light created at gaps between scattering crystallographic defects in a large
variety set of nano-gap III-V medium. No localized spots correlated to MFP
below ~14.5 nm is observed at second-harmonic collection at 390 nm. Experiment
and simulation resulted in the first direct observation of suppression of
Anderson light localization correlated to ~13 nm optical MFP that reveals a
fundamental constraint in electromagnetism and photonics.
