Sensitization of the luminescence of the Er3+ ions by Ce3+ ions in a YAG crystal

Highly efficient nonradiative energy transfer from Ce³⁺ to Er³⁺ was observed in a YAG:Ce³⁺:Er³⁺ crystal. The experiments showed that the excitation of the ⁴S_3/2 level was converted into a population inversion between the active Stark sublevels of the ⁴I_11/2 and ⁴I_13/2 levels characterized by the maximum efficiency in a YAG crystal. Quenching of the ⁴I_11/2 level of the Er³⁺ ion by the Ce³⁺ anions in YAG:Ce³⁺:Er³⁺ was slight. The contribution of the Ce³⁺ ions to the population of the active levels of the Er³⁺ ions in YAG:Ce³⁺:Er³⁺ was 15–20%.