Extra-cavity, wide-tunable, passively Q-switched Nd:YVO4/PPMgLN optical parametric oscillator

A wide-tunable, low-threshold, extra-cavity singly resonant optical parametric oscillator(OPO) has been reported, which is based on periodically poled MgO:LiNbO3 (PPMgLN). The OPO system, compact and simple, adopts a passively Q-switched Nd:YVO4 laser as the pump source and realizes quasi-phase-matched optical parametric oscillation at room temperature. The threshold value of the OPO system is only 0.27 W (single pulse energy of 4.5 μJ, pulse duration of 35 ns) at 1 064 nm. When the pump power is 1.35 W (pulse energy of 8.2 μJ, pulse duration of 35 ns), an idler output power of 161.9 mW at 3.202 μm, and a signal output power of 98.5 mW at 1.594 μm have been achieved, and this corresponds to a whole (idler+signal) optic-optic conversion efficiency of 19.3%. By shifting the PPMgLN crysta