Multicolor upconversion luminescence from RE3+-Yb3+ (REÂ =Â Er, Tm, Tb) codoped LaAlGe2O7 glasses

RE3+-Yb3+ (RE = Er, Tm, and Tb) codoped lanthanum aluminum germanate LaAlGe2O7 (LAG) glasses are prepared by melt-quenching method. The blank LAG glass has good transparency in UV/VIS/NIR/MIR range, which makes it suitable for RE ions doping. The doped glasses show strong upconversion (UC) emission under the excitation of a 980 nm laser diode assisted by two or three photons. The UC from Er3+/Yb3+ and Tm3+/Yb3+ codoped LAG glasses show high color purity. The mechanism is also discussed to explain the UC processes.