Tunable middle IR optical parametric oscillator for spectroscopic applications

The operation of a middle infrared laser source based on the tandem optical parametric oscillator (OPO) was demonstrated.The first stage was based on the nonlinear KTP crystal and produced up to 45 mJ of 1.57 µm radiation, while pumped by a commercial Q-switched Nd:YAG laser.The quality of signal beam was improved by using the unstable resonator.The AgGaSe2 crystal was used in the second stage OPO.Idler energies up to 1.2 mJ were generated in this stage within tuning range from 5 to 12 µm.