is a widely used crystal in nonlinear optics owing to its

Abstract We derive new temperature dependent Sellmeier equations for the extra-ordinary and ordinary refractive in-dices of 0.5 % MgO-doped stoichiometric LiTaO3 crystal. The equations are based on quasi phase-matched frequency conversion measurements, as well as on interferometric measurements of the thermal expansion and thermal dis-persion. These equations fit experimental data over wide spectral ranges: 0.35–6 µm for the extra-ordinary wave and 0.375–3.75 µm for the ordinary wave, from room tempera-ture up to 200°C. The nonlinear optical measurements set lower-limit values for the d33, d22, and d24 elements of the second-order susceptibility tensor χ(2) of 12.9, 1.54, and 0.46 pm/V, respectively. The interferometric measurements enable one to determine the linear and quadratic expansion coefficients of 1.45762e−5 1/°C, and 2.68608e−8 (1/°C)2, respectively. The Sellmeier equations are in good agreement with previously published data. PACS 42.65.An · 42.70.Mp · 77.84.D