Light manipulation in complex media: imaging, and beyond

by S. Gigan (Laboratoire Kastler-Brossel Ecole Normale Supérieure Paris, France)

Tuesday 12 Jan 2016, 11:00 → 12:00 Europe/Rome

Aula Rasetti (Dip. di Fisica - Edificio G. Marconi)

Scattering of light in heterogeneous media, for instance the skin or a glass of milk, is usually considered an inevitable perturbation or even a nuisance. Through repeated scattering and interferences, this phenomenon seemingly destroys both the spatial and the phase information of any laser illumination. At the spatial level, it gives rise to the well-known “speckle” interference patterns. At the temporal (or spectral) level, a short pulse entering a scattering medium will see its length greatly extended due to the multiplicity of possible path length light can take before exiting the medium. From an operative point of view, scattering greatly limits the possibility to image or manipulate an object with light through or in a scattering medium. Multiple scattering is a highly complex but nonetheless deterministic process: it is therefore reversible. Speckle is coherent, and can be coherently controlled and manipulated. By « shaping » or « adapting » the incident light, it is in principle possible to control the propagation and overcome the scattering process. I will present recent results from our group showing how light control allows not only imaging through or in a disordered medium, but also opens exciting possibilities for light control and light-matter interactions.