A study of cross-relaxation and temporal dynamics of lasing at 2 microns in Thulium doped ceramic

We report the characterization of the pump absorption and emission dynamic properties of a \tulio{} ceramic lasing medium using a three mirrors folded laser cavity. We measured a slope efficiency of 73\%, which allowed us to retrieve the cross-relaxation coefficient. The behavior of our system was modeled via a set of macroscopic rate equations in both the quasi continuous wave and the pulsed pumping regime. Numerical solutions were obtained, showing a good agreement with the experimental findings. The numerical solution also yielded a cross-relaxation coefficient in very good agreement with the measured one, showing that the cross-relaxation phenomenon approaches the maximum theoretical efficiency.