Luminescence enhancement of Pr3+ doped sol-gel silica glass as a result of Al3+ co-doping

Abstract Praseodymium (Pr3+) doped silica glass with varying Aluminum (Al3+) concentrations have been prepared using sol-gel technique. The glass samples produced have density (2.2 g/cm3) and refractive index (1.46) similar to that of fused silica. Judd-Ofelt parameters Ω2, Ω4 and Ω6 were obtained from the absorption spectrum in the visible region and used to calculate line strengths of transitions involved in cross-relaxation. Analyses of cross-relaxation mechanisms suggest higher probability for the 1D2 state. Photoluminescence emissions in the visible and NIR region were observed under 450 nm excitation. Slow annealing to 1000 °C minimizes hydroxyl quenching by reducing hydroxyl content thereby improving the luminescence. Al3+ co-doping also significantly enhance the luminescence, especially the 1D2 emission which is evidence of reduction in cross-relaxation.