ZnGep2-based optical parametric oscillator for µm generation

Operation of a ZnGeP2-based optical parametric oscillator (OPO) for generation of 8-11 μm radiation is studied. The primary source used to pump the OPO is a KTP-based OPO pumped by a Nd:YAG laser, giving up to 2 mJ pump energy at 2.07 μm at 20 Hz pulse rate. A conversion efficiency of 9% is obtained at 8 μm, with a beam quality M2 of 2.4-3. Wavelength tuning in the 8-11 μm range and simultaneous oscillation of two signal/idler pairs is demonstrated. Length matching effects between the OPO and the pump source are also observed. Simulations of the OPO show good agreement with the experimental results in general, but some discrepancies were noticed.