Characteristics and Mechanism of Up-conversion Luminescence in Er~(3+)/Yb~(3+)/Tb~(3+) Co-doped Oxyfluorogermanate Glasses

Up-conversion luminescence properties and energy-transfer 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 excitation power density.The energy transfer processes among Er3+,Yb3+ and Tb3+,and up-conversion mechanisms were discussed.