Spectroscopy, modeling, and laser operation of thulium-doped crystals at 2.3 /spl mu/m

Pulsed room-temperature lasers based on the thulium 2.3-/spl mu/m /sup 3/H/sub 4/-/sup 3/H/sub 5/ transition have been achieved in 1.5% Tm:YAG, 2% Tm:LuAG, and 1.5% Tm:YLF crystals using a pulsed alexandrite laser at 785 nm as the pump source in a collinear geometry. The absorbed energy thresholds (slope efficiencies) for 1.5% Tm:YAG, 2% Tm:LuAG, and 1.5% Tm:YLF lasers are measured to be 1.2 mJ (14%), 1.8 mJ (13%), and 1.0 mJ (18%), respectively, which are in good agreement with the theoretically predicted results. The experimental results indicate 1.0 mJ thulium to be the most optimum concentration for 2.3-/spl mu/m laser action. The thulium lasers are tuned around 2.3 /spl mu/m using an intracavity single birefringent plate of quartz.