Ion-ion upconversion excitation of the 4f5d configuration in Pr : Y3Al5O12- Experiments and Forster theory-based rate equation model

We observe visible pumping of the ultraviolet 4f5d emission of Pr3+ in Y3Al 5O12 by ion-ion upconversion. This process contributes significantly to the 4f5d population, indicating that it should be taken into account (along wi th excited state absorption) when Pr hosts are evaluated for possible upcon version pumped laser operation in the ultraviolet. In addition, we find tha t a single, time-independent energy transfer parameter cannot explain the o bserved 4f5d decay wave forms, but that the familiar Forster theory for ran ge-dependent strength of energy transfer can be adapted to explain the main features of our data. Forster theory leads to a formula which the authors believe can be used to assess the potential for upconversion-based lasing o n specific transitions. (C) 1999 American Institute of Physics. [S0021-8979 (99)07818-4].