Emission dynamics of heavily colored LiF crystals

LiF crystals colored with ionizing radiation have been used in recent times as active materials for pulsed laser emissions in the visible and near infrared region of the electro-magnetic spectrum. Among the various color centers which possess high emission efficiencies, the F(3)(+) center displays a peculiar optical cycle whose properties depend on temperature and pumping intensity. However a few effects discovered recently seem to imply the existence of interactions among the centers, which is a topic of paramount importance for applied and basic research. Preliminary results on samples containing high concentration of color centers have shown new dynamical effects, which in part can be explained in the frame of nonlinear optical processes and in part require a different approach in describing the optical cycle and its parameters.