Phase-matching properties of KNbO3 in the mid-infrared.

KNbO3 has been found to be phase matchable for type 1 second-harmonic generation up to 2.4 µm at 22 °C. The improved Sellmeier equations that correctly reproduce the nonlinear experiments thus far reported in the literature and our new experimental results for harmonic generation of CO2 laser harmonics between 3.5303 and 5.2955 µm are presented.