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Frequency Upconversion Emission of Er3+-Doped Strontium–Lead–Bismuth Glasses

Er3+-doped strontium–lead–bismuth glasses for developing potential upconversion lasers have been fabricated and characterized. Under 975 nm excitation, intense green and red emissions centred at 525, 546, and 657 nm, corresponding to the transitions 2H11/2→4I15/2, 4S3/2→4I15/2, and 4F9/2→4I15/2, respectively, were observed at room temperature. 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 525 and 546 nm emissions, and energy transfer upconversion for 657 nm emission.