We report a continuous-wave singly resonant optical parametric oscillator (OPO) based on periodically poled lithium niobate. The simple, two-mirror OPO,pumped by a 1.064-mu m Nd:YAG laser, had a 2.6-4.5-W threshold and an output of >1.2 W at 3.3 mu m and was tuned over 1.45-1.62 mu m (signal) and 3.98-3.11 mu m (idler). The noise characteristics and the spectral properties of the device are described. (C) 1996 Optical Society of America