Input/output energy in solid state dye random lasers.

A new approach to the problem of energy in solid state dye random lasers is presented. The measurements performed in terms of absolute energy show that the slope efficiency depends on the measurement conditions. In particular, in lasers with pumping in the picoseconds range, the result is really different if measured by recording the emission in the same time range or in a longer one (nanoseconds range). In the last case, no energy threshold is observed. A previously developed model has been applied to the solid state dye random laser. It is a rate-equations model, based on a distribution of paths with different lengths, which partially share population inversion. The results of the model are satisfactory and show that the dynamic behavior is pretty similar in solid state dye random lasers and in inorganic powders.