Infrared to visible upconversion in Er3+-doped lead oxyfluorosilicate glasses

The upconversion properties and mechanism of Er3+ ions have been studied for lead oxyfluorosilicate glasses containing Er2O3 concentrations from 0.2 to 2 mol%. Under 975 nm excitation, four emission bands centered at 411, 525, 543, and 655 nm corresponding to the 2H9/2→4I15/2, 2H11/2→4I15/2, 4S3/2→4I15/2, and 4F9/2→4I15/2 transitions of Er3+ ions, respectively, were simultaneously observed at room temperature. The bright green and red emissions are due to a two-photon upconversion process while the weak blue emission is determined by a three-photon upconversion process. Raman spectrum indicates that fluoride ions in the formation of glass network have important influence on upconversion luminescence of Er3+ in lead oxyfluorosilicate glasses. The intense upconversion luminescence of Er3+-doped lead oxyfluorosilicate glasses may be a potentially useful material for developing upconversion optical devices.