Quasi-three-level operation of Nd:GdVO₄ laser pumped by 879 nm laser diode

By use of novel 879 nm Laser Diode (LD), quasi-three-level transition in Nd:GdVO₄ crystal at room temperature is realized. For the crystal with Nd doped concentration of 0.2% and 3 mm × 3 mm × 3.8 mm in size, wavelength of 912 nm. The 912 nm laser with output power of 2.5 W when the pump power is 33 W, corresponding to a slope efficiency of 11% with respect to the pump power and a slope efficiency 38% with respect to the absorbed pump power. For the crystal with Nd doped concentration of 0.2% and 3 mm × 3 mm × 5 mm in size. The 912 nm laser with output power of 3.0 W is obtained when the pump power is 33 W, corresponding to a slope efficiency of 16% with respect to the pump power and a slope efficiency 45% with respect to the absorbed pump power. For the acousto-optic (A-0) Q-Switched regime, average output power of 660 mW and pulse duration of 22 ns is achieved at the repetition rate of 10 kHz, the peak power is up to 3 kW. The relationship between lasing threshold and the length and Nd doped concentration of crystal are theoretically analyzed. The influence of reabsorption loss on laser' s operation is discussed and the saturation effect of reabsorption loss is observed.