Control of optical propagation in atomic and diffusive media

This thesis has been devoted to the experimental investigation, supported by the development of theoretical and numerical model, on the propagation of light in atomic and diffusive media. In the first part, the control of propagation dynamics of optical pulses in slow and fast light regime has been reported. The topic of the second part of this thesis is the propagation of light through disordered media when gain is added. Such kind of optical systems, called random laser, exhibits a laser-like emission without the requirement of an optical cavity. A model based on a non-resonant feedback mechanism, where the extended modes are treated as possible paths inside the medium, has provided the framework for the interpretation of experimental data.