High-efficiency parametric converter based on KTP crystals

A high-efficiency extracavity parametric oscillator based on KTP crystals for converting radiation of Nd³⁺:YAG lasers at 1.064 μm to radiation at 1.573 μm is made and its oscillation characteristics are studied. A differential efficiency of 56.5% and a threshold energy density of 0.06 J  cm^–2 were obtained. The angular divergence of parametric emission did not exceed four diffraction limits in a wide range of pump energies. The feasibility of stable operation for a more than 30-fold excess of pump energy over the threshold value was obtained.