Optical transitions and frequency upconversion emission of Er3+ ions in novel lead-bismuthate glass

Er3+-doped strontiam lead bismuth glass for developing upconversion lasers has been fabricated and characterized. The Judd-Ofelt analysis was performed on the absorption spectrum and the transition probabilities, excited state lifetimes, and the fluorescence branching ratios were calculated and discussed. Under 975 nm excitation, intense green and red emissions centered at 525, 546, and 657 nm, corresponding to the transitions H-2(11/2) --> I-4(15/2), S-4(3/2) --> I-4(15/2), and F-4(9/2) --> I-4(15/2), respectively, were observed. The upconversion mechanisms are discussed based on the energy matching and quadratic dependence on excitation power, and the dominant mechanisms are excited state absorption and energy transfer upconversion for the green and red emissions. (C) 2004 Elsevier B.V. All rights reserved.