Highly-doped LuAG:Yb ceramics: synthesis, characterization, and quasi-CW laser performance

Abstract

This work presents the preparation and comprehensive characterization of polycrystalline Yb-doped lutetium aluminum garnet (Yb:LuAG) ceramics, with ytterbium concentrations ranging from 5 to 30 at.%. The ceramics were synthesized using chemical coprecipitation, followed by vacuum sintering and hot isostatic pressing. Samples achieved optical transmittance exceeding 82.9% at 810 nm. Structural analysis, microstructural observations, thermal conductivity measurements, and spectroscopic characterization were performed. Laser experiments utilized quasi-continuous wave (quasi-CW) pumping at 940 nm with output coupling transmission values of 10%, 15%, and 91.5%. The laser incorporating 5 at.% Yb-doped LuAG gain media with 10% output coupling operated at 1031 nm and demonstrated a slope efficiency of 57.3%. It was observed that reducing output coupling transmission increased the lasing wavelength for Yb concentrations ≥10 at.%, while the lasing threshold rose with increasing doping levels and output coupling transmission. These results affirm Yb:LuAG ceramics as promising gain media for solid-state lasers, particularly in thin-disk configurations that demand high doping levels and effective thermal management.