Abstract: The dynamic procedure of frequency upconversion excitation of 4f5d level of Pr^３＋ in Pr^３＋ ∶ZBLAN fiber was calculably simulated based on the population rate equations and the related transition theories. The distributions of the pump powers along the fiber and the effective fiber lengths under the different pump powers were studied. Pumping efficiency as a function of the pump powers was given. Possible population inversion between 4f5d level and 4f² levels was found from calculated results.

Key words: upconversion excitation, 4f5d level, Pr３＋∶ZBLAN fiber, rate equation