Type-II PPRKTP optical parametric oscillators in the 2 µm spectral range

Abstract

We experimentally explored the design parameter space for periodically poled R b : K T i O P O 4 (PPRKTP) structures in type-II optical parametric oscillators (OPOs) pumped at 1.064 µm and operating in the 1.8–2.5 µm range. This study identifies a set of Sellmeier expansions and thermooptic coefficients that can be used to accurately design the type-II PPRKTP structures in this spectral range. The performance of this OPO regime is investigated by employing different periodicities of PPRKTP, and the effective nonlinear coefficient is determined. Output at the mJ level with a bandwidth of better than 10 MHz is readily generated without optical damage. The temperature tuning rate of about 8 GHz/K of the central OPO frequency is substantially lower than in similar periodically poled lithium niobate devices and can be exploited for precise frequency tuning and easier thermal stabilization. The stimulated backward polariton scattering in the OPO cavities is also investigated and discussed.