Diode Pumped 2-μm Lasers Using Tm,Ho Codoped YLF, LuLF, LuAG and GdVO 4 Crystals

Tm, Ho codoped YLF, LuLF,and LuAG and GdVO4 crystals are very attractive for diode pumped 2-μm lasers. A comparison study of laser performance was made using a diode-pumped, quasi-end-pump scheme at various pulse repetition frequencies and temperatures. At 5 Hz and at an operating temperature of 300 K, normal mode laser output energies of 15.7 mJ (YLF) with a slope efficiency of 7.3%, 26.8mJ (LuLF) with that of 12.6% and 20.0 mJ (LuAG) with that of 10.8% were achieved using 5%Tm and 0.5%Ho, respectively. A Tm,Ho:GdVO4 laser was also investigated. It was found, in the case of GdVO4, that optimum Tm and Ho dopant concentrations were slightly lower than those for garnet and fluoride crystals. Using a 3% Tm,0.3% Ho:GdVO4 crystal, an output energy of 31.2 mJ with a slope efficiency of 14.5% was obtained in normal mode operation at room temperature.