Optical properties and upconversion fluorescence in Er3+-doped ZZA glass

Abstract We report the optical properties and upconversion emissions from the Er3+ ions in a ZrF4-based glass system ZrF4–ZnF2–AlF3. Judd–Ofelt intensity parameters ( Ω (t) with t=2,4,6) were obtained by analyzing the room temperature absorption spectrum. Upon 800 nm laser excitation, upconversion fluorescence was observed in blue, green and red regions at both 25 and 300 K. The main mechanism appears to be energy transfer among Er3+ ions in excited states. The green and red emissions result from a two-step process while the blue one is owing to a three-step energy transfer process.