Observation of weak localization of light in gold nanofluids synthesized using the marine derived fungus Aspergillus niger

Abstract

We have observed weak localization of light for the first time in gold nanofluids synthesized using the marine derived fungus Aspergillus niger. Coherent backscattering of waves by a disordered scattering medium is responsible for weak localization of light. We have directly observed this effect using polarized visible light and for different sized gold nanoparticles in nanofluids. The localization parameter kl* obtained from the observation is 1 < kl* < 5, which is the precondition for the weak localization of light. The kl* is controlled by the size and concentration of the particles in the nanofluids. Quadratic scaling is used to study the localization transition. The localization length obtained is nearly 225 nm. Gold nanoparticles have potential applications in biomedicine, imaging, catalysis and photonics.