Temperature-dependent Sellmeier equation for the index of refraction, n_e, in congruent lithium niobate

A Sellmeier equation for the extraordinary index of congruent lithium niobate is derived. The source data for the fit contain previously published data [Opt.Commun.17, 322 (1996); erratum 20, 188 (1997); J.Appl.Phys. 45, 3688 (1974)] and new measured tuning data for an optical parametric oscillator using periodically poled lithium niobate. Phase-matching predictions are accurate for temperatures between room temperature and 250 degrees C and wavelengths ranging from 0.4 to 5 mum .