Thermo-optic properties of Yb:Lu2O3 single crystals

A detailed study of thermo-optic properties of 1.5 at.% Yb:Lu2O3 single crystal is performed. Thermo-optic dispersion formulas are derived for dn/dT coefficient and thermal coefficient of the optical path. At the wavelength of 1.03 mu m, dn/dT = 5.8 x 10(-6) K-1. High-precision temperature-dependent measurements of the thermal expansion coefficient alpha are performed. At the room temperature (RT), alpha = 5.880 +/- A 0.014 x 10(-6) K-1. Temperature dependence of the bandgap is analyzed, yielding RT value of E (g) = 5.15 eV and dE (g)/dT = -3.7 x 10(-4) eV/K. Sensitivity factor of the thermal lens is calculated for a diode-pumped Yb:Lu2O3 crystal versus the pump spot radius and crystal temperature.