Highly efficient low-threshold tunable all-solid-state intracavity optical parametric oscillator in the mid infrared

An intracavity critically phase-matched optical parametric oscillator (OPO) was demonstrated with a LiNbO3 crystal placed inside the resonator of a diode side-pumped Q-switched Nd:YAG laser. The OPO acted as a singly resonating cavity on the signal with a threshold below 10 MW/cm(2). Output energy as high as 640 mu J was observed at the idler wavelength of 3.7 mu m, which corresponds to a conversion efficiency of 1.8% from diode light to idler light. Tunability over the wavelength range 3.3 - 4.15 mu m was obtained by rotation of the LiNbO3 crystal. (C) 1996 Optical Society of America