Diode-Pumped Nd:KGd(WO4)2 Laser: Lasing at Fundamental and Second Harmonic Frequencies

High-power cw and quasi-cw lasing at the fundamental and second harmonic frequencies is obtained from Nd:KGd(WO (4) ) (2) lasers based on Np- and Ng-cut crystals pumped longitudinally by a diode laser at 879 nm. Because of different crystal lengths, the limiting pump power beyond which the crystals undergo thermomechanical damage is 26.8 W for the N (p) -cut and 17.3 W for the N (g) -cut. At these pump powers the cw outputs at lambda = 1067.2 nm are 9.4 and 5.4 W, respectively, and the N (g) -cut crystal output is TEM (00) at the fundamental frequency. With quasicontinuous pumping at a 10% duty cycle the instantaneous laser power reaches similar to 11 W for both cuts with a periodic duration of 10-20 ms. The differential lasing efficiency relative to the absorbed pump power is 66.4% for cw lasing and 77.4% for quasi-cw operation. With intracavity frequency doubling using a KTP crystal, better results were obtained with the N (g) -cut crystal because of its simpler thermal lensing. The maximum second harmonic power was similar to 1.1 W for cw operation and similar to 2.6 W for quasi-cw operation with a diode laser power of 27.3 W.