Energy transfer mechanism and lasing performance in rare-earth-codoped ZBLAN

Energy transfer dynamics in fluorozirconate glass doubly-doped with Yb 3+ :Er 3+ and Ce 3+ :Er 3+ have been analyzed by using rate equation formalism. For the Yb 3+ :Er 3+ -ZBLAN glass, the macroscopic energy transfer parameters, cross-relaxation coefficients, were derived to be 1.1*10 -17 s -1 cm 3 and 2.0*10 -17 s -1 cm 3 for the forward energy transfer (Yb 3+ → Er 3+ ) and the backward transfer (Er 3+ → Yb 3+ ), respectively. After experimentally investigating fluorescence characteristics of Er 3+ ions in the Ce 3+ :Er 3+ -ZBLAN glass, taking into account of up-conversion and energy transfer effect, a resonant cascade energy transfer model was developed, with which the operating mechanism of the Ce 3+ :Er 3+ -ZBLAN fiber laser was explained theoretically. The potentiality of the rare-earth-codoped fluoride glass as one of the most promising laser materials is demonstrated.