Static contribution to thermal shifts of spectral lines in gadolinium gallium garnet Gd3Ga5O12:Nd3+ laser crystal

Abstract

The static contribution due to lattice thermal expansion and the vibrational contribution due to electron–phonon interaction to the thermal shifts of the spectral lines E1(R1 → Z5) and E2 (R2 → Z5) in the high-power laser crystal gadolinium gallium garnet Gd3Ga5O12 (GGG):Nd3+ are studied by analyzing the observed pressure- and temperature-dependence of these spectral lines. It is found that the static contribution due to thermal expansion in magnitude is greater than, and it in sign is opposite to the vibrational contribution due to electron–phonon interaction. So for the theoretical study of thermal shifts of the spectral lines in GGG:Nd3+ and other similar “hard” crystals, the neglect of the contribution due to the lattice thermal expansion suggested in the previous papers is unsuitable.