Thermo-optic dispersion formula of KNbO3 for mid-infrared OPO

The improved Sellmeier's equations and thermo-optic dispersion formula that reproduce well our experimental results for harmonic generation of CO 2 laser harmonics at 3.5303 - 5.2955 micrometers are presented. These formulas are believed to be highly useful for predicting the temperature-tuned 90 degree(s) phase-matched OPO in the mid-infrared.