Up-conversion luminescence of Er 3+ ions in lead-free germanate glasses under 800 nm and 980 nm cw diode laser excitation

Abstract Up-conversion luminescence spectra of Er3+ ions in multicomponent oxyfluoride glasses GeO2 – BaO – BaF2 – Ga2O3 – Er2O3 were examined. It was found that the up-conversion luminescence spectra of Er3+ are dependent on pumping wavelengths. The spectra recorded upon the excitation at 800 nm contained an intense green up-conversion luminescence corresponding to the 2H11/2, 4S3/2 → 4I15/2 transitions and a very weak red luminescence related to the 4F9/2 - 4I15/2 transition. In spectra recorded upon 980 nm excitation the contribution of the red luminescence was markedly higher. The interaction mechanisms involved in up-conversion processes are proposed and observed dependence of intensity of up-converted luminescence on excitation power is discussed. The experimental results suggest that Er3+ singly doped lead-free oxyfluoride germanate glass is useful for up-conversion luminescence applications.