Fabrication and photoluminescence properties of Cr:YAG and Yb,Cr:YAG transparent ceramic

•The optical transmittance of Yb,Cr:YAG and Cr:YAG reaches 83% at 1200 nm and 81% at 1400 nm, respectively.•The Yb,Cr:YAG ceramics exhibit a pore free structure with an average grain size of about 5 μm.•A sharp emission peak of 694 nm appeared and the emission intensity enhanced with the increase of the Cr3+ concentration.•The fluorescence lifetime and emission intensity of Yb3+ in Yb,Cr:YAG ceramic is lower than that of Yb3+ in Yb:YAG ceramic.•Yb,Cr:YAG transparent ceramics could be a potential material for passive self-Q-switched solid-state laser.

Cr:YAG and Yb/Cr:YAG transparent ceramics containing Ca as charge counter element were fabricated by vacuum sintering technique using the co-precipitation synthesis of raw powders. Their spectral and luminescence properties as well as the influence of Cr3+ concentration on the optical properties of Yb,Cr:YAG ceramic were investigated. Results show the transmittance of 10 at.% Yb, 0.25 at.% Cr:YAG and 0.25 at.% Cr:YAG reaches 83% at 1200 nm and 81% at 1400 nm, respectively. And the Yb,Cr:YAG ceramics exhibit a pore free structure with an average grain size of about 5 μm. After annealing, most of Cr3+ ions transform into Cr4+. In the case of excitation wavelength of 440 nm, a sharp emission peak of 694 nm appeared in the Yb,Cr:YAG ceramic before annealing and the band enhanced with the increase of the Cr3+ concentration, which is attributed to the 4T2g−4A2g fluorescence transition. The emission spectrums and fluorescence decays manifest that both the luminescent intensity and the lifetimes of Yb,Cr:YAG are lower than Yb:YAG ceramic and the lifetimes of Yb,Cr:YAG and Yb:YAG are 0.93 and 2.38 ms, respectively. This results demonstrate the existence of the ground state absorption of Cr4+ in the Yb,Cr:YAG ceramic. Experimental evidence proved that Yb,Cr:YAG transparent ceramics could be a potential material for passive self-Q-switched solid-state laser.