Measurement of temperature-dependent absorption and emission spectra of Yb:YAG, Yb:LuAG, and Yb:CaF_2 between 20 °C and 200 °C and predictions on their influence on laser performance

Abstract

Accurate values of the emission and absorption cross sections of Yb:YAG, Yb:LuAG, and Yb:CaF2 as a function of temperature between room temperature and 200 °C are presented. For this purpose, absorption and fluorescence spectra were measured using a setup optimized to reduce the effect of radiation trapping. From these data, emission cross sections were retrieved by combining the Fuchtbauer–Ladenburg equation and the reciprocity method. Based on our measurements, simple estimations illustrate the effect of temperature shifts that are likely to occur in typical laser setups. Our results show that even minor temperature variations can have significant impact on the laser performance using Yb:YAG and Yb:LuAG as an active medium, while Yb:CaF2 appears to be rather insensitive.