Ho:Tm lasers. II. Experiments

For pt.I see ibid., vol.32, no.1, pp.92-103 (1996). Laser performance of Ho:Tm:YLF and Ho:Tm:YAG lasers are compared under a wide variety of experimental situations. Laser diode pumping is simulated using a Cr:BeAl/sub 2/O/sub 4/ laser tuned to the absorption peak of the Tm/sup 3/H/sub 4/ manifold for the respective laser material. Laser performance is characterized by experimentally determining the threshold and slope efficiency, and compared with predicted results of a rate equation model developed in the companion paper. Energy transfer parameters for the rate equation model are calculated using the theory developed in that paper. For these experiments, four different pump pulselengths, six different output mirror reflectivities, different Ho concentrations and different length laser materials were evaluated. Using Ho:Tm:YAG an optical slope efficiency of 0.36 was achieved while with Ho:Tm:YLF an optical slope efficiency of 0.50 was reached.