Concentration dependence of visible luminescence from Pr3+-doped phosphate glasses

Abstract To clarify the concentration dependence of visible fluorescence of Pr 3+ , a series of phosphate glass samples with Pr 3+ concentration from 0.05 to 3.0 mol% were fabricated. Steady and dynamic spectroscopic characteristics of Pr 3+ -doped phosphate glasses were systematically investigated. When the Pr 3+ concentration was small, only one visible fluorescence band can be observed at 596 nm, which was ascribed to the transition of 1 D 2  →  3 H 4 . With increasing Pr 3+ concentration from 0.05 to 0.5 mol%, since the multi-phonon relaxation rate of 3 P 0 was largely quicker than that of 1 D 2 . Increasing Pr 3+ concentration from 0.5 to 3 mol%, increasing two other fluorescence bands at 612 nm and 640 nm, which were assigned to the transitions of 3 P 0  →  3 H 6 and 3 P 0  →  3 F 2 , respectively. It was due to the cross relaxation probability between [ 1 D 2 : 1 G 4 ] and [ 3 H 4 : 3 F 4 ] increased, which results in quicker decay rate of 1 D 2 . The fluorescence lifetime of 1 D 2 decreased from 173 to 6 μs with increasing Pr 3+ concentration from 0.1 to 3 mol%, which due to the cross relaxation probability between [ 1 D 2 : 1 G 4 ] and [ 3 H 4 : 3 F 4 ] increased, resulting in quicker decay rate of 1 D 2 . Fitting the concentration dependence of fluorescence lifetime demonstrated that the cross relaxation arising from dipole-dipole interactions between Pr 3+ ions.