Thermomechanical properties of Yb3+ doped laser crystals: Experiments and modeling

Abstract

Thermal conductivity values of several laser materials were determined by photothermal measurements and compared to predicted values. The effect of the ytterbium doping concentration could be modeled using a simple cationic mass difference model. For ytterbium content corresponding to an absorption coefficient of 10 cm−1 (or 85% absorption of the pump power) Yb:GdVO4 (c-axis) and Yb:Gd3Ga5O12 laser materials present the highest measured thermal conductivity values of 8.1 W m−1 K−1 and 7.7 W m−1 K−1, respectively. Yb:Y3Al5O12, Yb:Lu3Al5O12, Yb:CaGdAlO4, and Yb:YAlO3 belong to the 6–7 W m−1 K−1 range while Yb:CaF2 and Yb:Lu2SiO5 are situated in the 5–6 W m−1 K−1 range. Other matrices such as Yb:SrLaGa3O7, Yb:CaGdAl3O7, Yb:SrGdGa3O7, and Yb:BaLaGa3O7 have thermal conductivity values lower than 5 W m−1 K−1. With the knowledge of the thermal conductivities and the determination of the thermal expansion coefficients, thermal shock parameters are evaluated for several ytterbium doped laser hosts.