Intracavity continuous-wave singly resonant optical parametric oscillators

The operating characteristics and experimental performance of continuous-wave (cw) singly resonant optical parametric oscillators (ICSRO's) pumped internally to the cavity of the pump laser are described. We outline the operating principles, design criteria, and optimization procedure for maximum downconversion and power extraction, and highlight the merits of the intracavity approach, including low input power requirement, potential for 100% downconversion efficiency, high-power operational stability, and power scalability. The predicted behavior and many of the attractive practical features of these devices are demonstrated in cw ICSRO's based on the birefringent nonlinear materials KTiOPO4 and KTiOAsO4 and on the quasi-phase-matched nonlinear materials periodically poled LiNbO3, RbTiOAsO4, and KTiOPO4, pumped internally to cw Ti:sapphire- and diode-pumped solid-state lasers. Maximum extracted infrared powers of 1.46 W, downconversion efficiencies of as much as 90%, minimum input power thresholds of 310 mW, and wavelength tuning to 4 mu m in the mid-infrared are demonstrated. (C) 1999 Optical Society of America [S0740-3224(99)01809-3].