Concentration-dependent and enhanced luminescence in Ge23.5Ga11.5Se65 glasses and glass-ceramics doped with Er3+

We have reported the fabrication and characterization of Ge23.5Ga11.5Se65 glasses and glass-ceramics with different Er3+ concentrations. It was found that, the emission properties of the bulk glasses showed the fluorescence intensity and lifetime increased until they reached a maximum, and then decreased with increasing Er3+ concentration. This is due to concentration quenching effect although the maximum dissolving concentration of Er3+ can be up to ∼1 wt% of Er. A careful thermal process has led to the formation of ∼80 nm β-Ga2Se3 crystalline particles in Ge23.5Ga11.5Se65 glasses doped with 0.8 wt% of Er3+. By monitoring 4I13/2 → 4I15/2 Er3+ transition, almost fourfold enhancement in the intensity and ∼0.57 ms prolongation in the lifetime of near-infrared fluorescence at 1.54 μm have been observed after crystallization. It was assigned to the decreasing phonon energy of the local environment of Er3+ ions during the crystallization.