Charging Gd₃Ga₅O₁₂:Pr³⁺ persistent phosphor using blue lasers

Trap filling studies of persistent phosphors using visible-light excitation have important implications on both fundamental luminescence research and practical applications. We report here an up-conversion charging (UCC) design of Gd₃Ga₅O₁₂:Pr³⁺ persistent phosphor upon excitation with blue lasers. As an example, long-lasting emission from Pr³⁺ has been achieved in the phosphor after the traps are filled by subsequently absorbing two 450 nm excitation photons from a blue diode laser. Spectroscopic investigations reveal that the composition of UCC intermediate state is predominantly that of ³P₀ state of Pr³⁺ in the phosphor. Our work provides a major step toward developing the UCC design, which enables new properties of persistent luminescence to be discovered and new applications of persistent phosphors developed.