Experimental investigation of laser diode end pump Tm : YAG laser

Laser diode (LD) end pumped Tm : YAG laser was experimentally investigated. The threshold pump power and slope efficiency were discussed by using the quasi-three-level rate equations. The stability conditions of Tm : YAG laser resonators and mode matching between the pump beam and the cavity mode were analyzed by using the ABCD matrix. In the experiments a 785 nm fiber-coupled LD was used to pump the Tm : YAG laser. 4.04 W continuous output power was obtained at 2.018 μm with the laser crystal temperature of 5°C in a plane-concave cavity. The slope efficiency of the Tm : YAG laser was 35.4% and the total optical-optical conversion efficiency was 26.4%. The threshold, output power and slope efficiency of Tm : YAG laser at different crystal temperatures were investigated. The experimental results agree with the theoretical estimation. The influences of the laser resonator on the laser output power and efficiency were also discussed.