Optical parametric oscillator of quasi-phasematched LiNbO3 pumped by a compact high repetition rate single-frequency passively Q-switched Nd:YAG laser

We report on an efficient diode pumped compact source of pulsed tunable infrared radiation based on a high repetition rate single frequency passively Q-switched Nd:YAG laser and an optical parametric oscillator (OPO) of quasi-phase matched LiNbO3. When pumped by 5.4 W of 810 nm cw diode laser radiation the Nd:YAG laser (which is passively Q-switched by a Cr4+:GSGG saturable absorber) oscillates on a single-longitudinal mode and emits in a diffraction limited beam light pulses with duration of 2 ns, pulse energy of 100 mu J, repetition rate of 1.1 kHz and average power of 110 mW. This radiation excites an OPO of quasi-phase matched LiNbO3. The OPO generates signal and idler radiation which is tunable in the range of 1.46-1.61 mu m and 3.13-3.92 mu m, respectively. Tuning is achieved by using 8 different poling periods (Lambda = 28.5-29.9 mu m) and by changing the crystal's temperature in the range of 80-160 degrees C. The measured signal pulse energy is E-S = 22 mu J, the average signal output power P-S = 24 mW, the measured idler power P-1 = 2.5 mW and the pump depletion 33%. (C) 1998 Elsevier Science B.V.