Periodically poled lithium niobate and quasi-phase-matched optical parametric oscillators

Since their introduction two years ago, quasi-phase-matched (QPM) optical parametric oscillators (OPO's) have moved into the mainstream of OPO research. This has been made possible by continuing improvements and availability of the microstructured nonlinear material periodically poled lithium niobate (PPLN), Demonstrations of PPLN OPO's now span the range of pulse formats and power levels. The most significant area of development is low-peak-power devices where operation with conventional materials is difficult. In this paper, we describe the current state of this research, including OPO's pumped by high-repetition-rate (>30 kHz) Q-switched diode-pumped solid-state lasers, and CW singly resonant OPO's with >3-W output power in the 3-4-mu m range.