Refractive Index as a Function of Temperature in LiNbO3

The refractive index vs wavelength of LiNbO3 has been measured between 0.42 μ and 4.0 μ at 25°C and 80°C. The measured values have been expanded in a three-term polynomial by a least-squares best fit and the temperature dependence of the polynomial coefficients determined. The results are used to calculate the phase-matching temperatures normal to the optic axis in nonlinear optical second-harmonic generation and parametric experiments. The calculated results are compared with experimentally measured values.