Extracavity parametric oscillation at 1.5 and 2 μm upon pumping from an Nd3+:YAG laser

The lasing characteristics of extracavity KTP optical parametric oscillators (OPOs) emitting at 1.57 and 2.14 (2.19) μm upon pumping by multimode Nd³⁺:YAG lasers at 1.064 and 1.32 (1.34) μm, respectively, are studied. The thresholds, conversion efficiencies, and divergences of the output radiation for linear and ring OPOs emitting at 1.57 μm are compared. Low thresholds, a high (up to 40%) conversion efficiency, and a low (no greater than 3.5 mrad) divergence of the output radiation were obtained in a three-mirror ring OPO when the pump energy exceeded the threshold by a factor of ten. Emission at 2.14 and 2.19 μm was obtained in a three-mirror ring OPO pumped by Nd³⁺:YAG laser at 1.32 and 1.34 μm, respectively. The OPO lasing parameters are found to be of practical interest. A compact and efficient ring OPO is built for converting radiation from Nd³⁺:YAG lasers to radiation in the 1.5 – 2-μm range.