Infrared to visible upconversion of Er3+ and Er3+/Yb3+ codoped lead–niobium–germanate glasses

Abstract Infrared-to-visible upconversion processes have been investigated in Er 3+ -doped and Er 3+ /Yb 3+ codoped lead–niobium–germanate glass (55GeO 2 –25PbO–20Nb 2 O 5 ) with a fixed 0.5 mol% Er 3+ concentration and different Yb 3+ concentrations ranging from 0 to 2 mol%. Visible emissions at 526, 547, and 660 nm corresponding to the 2 H 11/2  →  4 I 15/2 , 4 S 3/2  →  4 I 15/2 , and 4 F 9/2  →  4 I 15/2 transitions were observed under continuous wave excitation at 978 nm. The quadratic pump power dependence of these emissions indicates a two photon upconversion process. An enhancement of the visible upconversion fluorescence in Er 3+ /Yb 3+ codoped samples is confirmed due to efficient energy transfer from Yb 3+ to Er 3+ ions.