Measurement of refractive indices and thermal refractive-index coefficients of LiNbO(3) crystal doped with 5 mol. % MgO.

The principal refractive indices and the thermal coefficients for a LiNbO(3) crystal doped with 5 mol. % MgO have been measured by a minimum-deviation method for the wavelengths of 0.53975, 0.6328, 1.0795, and 1.3414, microm in the temperature range 20-154.5 degrees C. The constants of modified Sellmeier equations are all given in the described temperature range. The measured results were used to calculate the type I critical phase-matching angles for 1.0795- and 1.3414-microm second-harmonic generation at room temperature and the noncritical phase-matching temperature for 1.0795-microm second-harmonic generation for LiNbO(3) crystal doped with 5 mol. % MgO. The values obtained agree well with the experimental results.