Luminescence sensitization and its application to enhance the efficiency of solid-state laser active media

Excited-state populations of energy acceptors are determined for arbitrary and time-varying relationships between the transfer probability and natural excited-state lifetimes of energy donors and acceptors for an arbitrary pump spectrum using cw and pulsed excitation. Various familiar limiting situations are particular cases of the general situation under discussion. The theoretical results were verified experimentally for a Y₃Al₅O₁₂:Cr³⁺:Nd³⁺ crystal. Quantitative agreement was obtained between theory and experiment. The method developed can be used to calculate the improvement in the excited-state population of the lasing particles as a result of sensitization in doubly activated media for solid-state lasers.