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 photoluminescence emission and kinetics of the Yb:YAG ceramics revealed the corresponding 2F5/2 → 2F7/2 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 ∼0.030 cm−1, a value close to that observed for single crystal.