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Colóquio: Anderson localization of light in a colloidal suspension (TiO2@Silica) (Prof. Dr. Ernesto Jimenez Villar - UFPE)

Anderson localization is one of the most interesting phenomena in solid-state physics. Particularly, localization of light is an open research frontier which, besides being a fundamental topic it also could present significant applications. Since Phillip Anderson proposed that scattering from disorder could bring transport to a complete halt, this phenomenon has greatly motivated scientists. In that seminal work, Anderson addressed the problem from a quantum vision, i.e taking into account the wave nature of the electron. Accounting that Anderson localization is a wave phenomenon (interferential) Sajeev john and Anderson himself extended this idea to optics. Optics seems an ideal framework to study localization and associated phenomena, due to non-interacting nature (seeming) of photons. In fact, various pioneering experiments that studied the transmission of electromagnetic waves through strongly disordered media have claimed the observation of Anderson localization of light. However, these works were questioned firstly by opponents and later refuted by their authors. The inelastic scattering processes (residual absorption or nonlinear phenomena) can lead to a decrease in the photon coherence length, disabling the interference effects (localization). Our study in course, recently published at Nanoscale cover (Anderson localization of light in a colloidal suspension), reports several pieces of experimental evidence of localization of light in a colloidal suspension of core–shell nanoparticles (TiO2@Silica). The light confinement (localization) has been achieved into a suspension colloidal (TiO2@Silica). We demonstrate the crossover from a diffusive transport to a localization transition regime as nanoparticle concentration is increased, and that a striking phenomenon of enhanced absorption arises at localization transition. This strongly disordered medium in liquid suspension opens new avenues in the photonics field, ranging from the designing and manufacture of novel photochemical reactors, powerful sensing tools and other advanced photonic devices, to investigations into fundamental topics, such as the light quantum nature and other phenomena involving photon interactions.