93% pump depletion, 3.5-W continuous-wave, singly resonant optical parametric oscillator

We report two cw, singly resonant optical parametric oscillator (OPO) configurations based on periodically poled lithium niobate that result in significantly higher efficiency and output power than in previous studies. Using four-mirror OPO cavities and pumping with a 1.064-mu m Nd:YAG laser, we observe 93% pump depletion and obtain similar to 86% of the converted pump photons as useful idler output. The single-beam, in-the-bucket idler output power of 3.55 W at 3.25 mu m corresponds to similar to 80% of quantum-limited performance. We measure and compare the amplitude noise and spectral bandwidth of the two configurations. We also demonstrate >1 W of tunable cw output over the 3.3-3.9-mu m spectral range. (C) 1996 Optical Society of America