Blue-shifted random-laser-mode selection in gain-assisted anisotropic complex fluids

Random laser action in organic materials is of great topical interest that is fueled by the rapid development of active compounds and new dye molecules. We propose a pure-diffusive model to describe the strong connection established between a dye-host interaction and the scattering when considering an anisotropic complex fluid. The model considers multiple scattering induced by dielectric tensor fluctuations and a suitable quantistic description for light amplification in order to explain the generation of the narrow-band blue-shifted lasing mode experimentally observed in such systems. We also find that the introduction of a strong intermolecular force field provides the condition to enhance diffusive processes. The agreement between experimental observations and simulations advances the understanding of the physical mechanism behind mode selection in these systems.