Up-conversion fluorescence and low-temperature emission in Er3+-doped GeGaS–CsBr glasses

Abstract Optical properties of Er-doped chalcohalide GeGaS–CsBr glasses have been investigated as a function of Er and Ga concentrations. Nominal compositions of (Ge 0.25 Ga. 0.10 S 0.65 ) 0.9 (CsBr) 0.1 and (Ge 0.23 Ga. 0.12 S 0.65 ) 0.9 (CsBr) 0.1 glassy hosts have been chosen for this study. The effects of Er content and host composition on 1.5 μm emission of Er 3+ ions, measured at low-temperature of 20 K under excitation by 514.5 nm, have been specified. Besides, the up-conversion fluorescence of Er 3+ ions pumped at 795 nm is reported. Two intense emission bands in the green and one weak emission band in the red regions around 530, 554 and 644 nm have been observed, and were attributed to 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 of Er 3+ ions, respectively. The simplified energy-level diagram of Er 3+ ion has been used to identify the observed up-conversion fluorescence bands in visible region.