Fabrication, photoluminescence and terahertz absorption properties of Yb:YAG transparent ceramics with various Yb dopant concentrations

Highly transparent Yb:YAG laser ceramics with various Yb3+ doping level were successfully fabricated through vacuum sintering of co-precipitated powders in combination with the hot isostatic pressing process. The effects of various Yb3+ dopant concentrations (1-15 at.%) on the photoluminescence, terahertz absorption and optical characteristics of Yb:YAG transparent ceramics were investigated. Characterizations of the Near-IR photo-luminescence emission and kinetics of the Yb:YAG ceramics revealed the corresponding F-2(5/2) -> F-2(7/2) characteristic bands of Yb3+ and the lifetime enhanced with increasing Yb3+ dopant concentrations, confirming no concentration quenching effect in Yb:YAG. Measurements of terahertz absorption properties of Yb:YAG transparent ceramics by a time-domain spectroscopy evidenced that both the cutoff frequency and terahertz absorption coefficient of Yb:YAG samples depended upon the Yb3+ dopant concentrations. The underlying mechanisms by which such Yb3+ dopant concentrations affected the terahertz absorption and optical properties were also discussed. The optical attenuation loss values were measured at 1064 nm for all the samples, to be similar to 0.030 cm(-1), a value close to that observed for single crystal.