Upconversion luminescence of Er3+ in alkali bismuth gallate glasses

Frequency upconversion of Er3+ in alkali bismuth gallate glasses have been investigated. The upconversion mechanisms are discussed, and the dominant mechanisms are excited state absorption for the 2H11/2→4I15/2 and 4S3/2→4I15/2 transitions, and energy transfer upconversion for the 4F9/2→4I15/2 transition. Intense green (around 525–550 nm) and red (around 660 nm) emission bands were observed under 800 nm excitation. At a pump intensity of 15.6 W/cm2, frequency upconversion efficiencies of 2.1×10−2 and 4.8×10−3 were obtained for the green and red emissions, respectively. The results are the highest among doped oxide glasses, and are comparable to those reported for Er3+/Yb3+ codoped fluoride glasses.