Characteristics and Mechanism of Up-conversion Luminescence in Er3+/Yb3+/Tb3+ Co-doped Oxyfluorogermanate Glasses

Up-conversion luminescence properties and energytransfer processes in Er3+,Yb3+ and Tb3+ single doped or co-doped oxyfluorogermanate glasses were studied under 980nm laser excitation. Green and red up-conversion emissions around 524, 546 and 658nm which can be assigned to the Tb3+∶5D4→7FJ (J=5 and 0) and Er3+∶(2H11/2, 4S3/2 and 4F9/2)→4I15/2 transitions, respectively, were strongly observed at room temperature. Up-conversion luminescence intensity depended on the YbF3, TbF3 concentration and excitationpower density. The energy transfer processes among Er3+, Yb3+ and Tb3+, and up-conversion mechanisms were discussed.