Preparation and photoluminescence properties of SrY2O4:Yb3+, Er3+ powders

Yb3+/Er3+ co-doped SrY2O4 powders are prepared by developing a nitric-decomposition method. Under 980 nm laser excitation, the green and red up-conversion emissions are observed at around 549 and 661 nm, which are attributed to the transitions of 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 of Er3+ ions, respectively. The intensity ratio of the red emission to the green one increases with Yb3+ doping concentration. A quadratic dependence of the two emissions on excitation power is obtained, indicating that a two-photon process populates the 4S3/2 and 4F9/2 levels for the SrY2O4 powders. Especially, it is found that at lower excitation power, Yb3+ doping concentration has an important influence on the slopes of the emission intensity versus excitation power, similar with the excitation power. The results can be helpful for the design and applications of low-cost near-infrared laser diodes.