Characterization of radiative and nonradiative Processes in Nd:YAG lasers by comparing direct and band pumping

Heat generation and laser performance of Nd:YAG oscillators pumped in two regimes, band pumping at /spl sim/808 nm and "thermally boosted" (TB) pumping at 884.5 nm, are compared. The crystal, pumped with a Ti:sapphire laser, lased with slope efficiencies of 52% and 57% when pumped at 802 and 884.5 nm, respectively. The heat generated during lasing was found to be 27% lower with TB pumping as compared to traditional band pumping. Moreover, the experimental results suggest that the coupling efficiency between the pump band and the upper lasing level (the quantum efficiency) is unity, and about 8% of the upper lasing level population decays via nonradiative channels.