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 H-2(11/2)-->I-4(15/2) and S-4(3/2)-->I-4(15/2) transitions, and energy transfer upconversion for the F-4(9/2)-->I-4(15/2) 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/cm(2), frequency upconversion efficiencies of 2.1x10(-2) and 4.8x10(-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. (C) 2000 American Institute of Physics. [S0003-6951(00)04730-6].