Grand Séminaire d'Institut

Vendredi 10 Mars 2017 à 11h00.

Random Lasers and the Glassy Behavior of Light

''Random Lasers (RLs) differ from conventional lasers as the feedback is provided by scattering rather than by a set of static mirrors. The scatters can be passive, and therefore embedded in a gain medium, or active, playing a double role of scattering and gain medium. Examples of the former are colloids with laser dyes and TiO2 particles whereas the latter includes ZnO powders or nanocrystals containing rare-earth ions. Although operating mirrorless, RLs present cavity modes that may compete and originate extreme intensity fluctuations. The basic properties of RLs and applications have been discussed by several authors who exploited the short temporal and spatial coherence of RLs to demonstrate their advantages with respect to conventional lasers for some applications. The recent studies of RLs as a photonic platform for investigation of complex systems such as spin glass, has opened new cross-disciplinary avenues for the understanding of the RLs behavior. In particular, the unified theoretical description of the mechanisms underlying strong Lévy intensity fluctuations and the photonic replica-symmetry-breaking glassy phase has been accompanied by demonstrations of photonic phase transitions in diverse spatial structures (1D, 2D and 3D) and physical arrangements (liquid and solid state). In this talk I will review the general characteristics and properties of RLs and discuss the recent results based on the analogies of RLs with other complex systems.''