Lithium niobate: Wavelength and temperature dependence of the thermo-optic coefficient in the visible and near infrared

The thermo-optic coefficient of lithium niobate (LiNbO<inf>3</inf>) has been measured in the temperature range from 10 to 160 °C using an interferometric setup. Undoped and magnesium-doped congruently melting LiNbO<inf>3</inf> and undoped stoichiometric LiNbO<inf>3</inf> were studied over a wide wavelength range in the visible and near infrared (450-600 nm and 900-1130 nm) using a frequency-doubled cw optical parametric oscillator. Experimental results for congruently grown lithium niobate were aggregated using a Schott equation to describe the wavelength and temperature dependence of the thermo-optic coefficient.