Ultrafast optical pulse interactions in active disordered condensed matter

The goal of this research is to better understand the basic physics that governs the behavior of short-pulsed light propagating in scattering media where either the host medium or the scattering particles exhibit emission or absorption interact with the incident light in form of absorption or stimulated emission.; The temporal and spectral dynamics from the interactions of optically active disordered-media with ultrashort optical pulses is the focus of the research performed in this thesis. The interaction processes studied are optical gain, spectral narrowing, fluorescence and pulse lifetime reduction and transport of ultrashort optical pulses in disordered media containing optically active discrete scattering particles. Linear and nonlinear effects are presented where the propagation of picosecond and femtosecond laser pulses in active disordered media is measured experimentally and compared with the theories of Boltzmann radiative transport and diffusive propagation of radiation in disordered media.; Active media can be involved in optical processes in disordered media where either the propagation of optical radiation can result in gain or absorption upon optical excitation. A study of optical scattering in non-discrete media such as the biological heterogeneously-continuous scattering tissues is carried out as well. Lasing in random media is one of the outcomes of these results. The optical gain of optically excited active media is divided into clear subdivisions of Amplified Spontaneous Emission, Stimulated Emission and Laser Emission by characterizing them by their temporal and spectral emission.