Abstract
In this paper, we numerically investigate the fluorescence decay of Tm-doped tellurite glasses with different dopant concentrations. The aim is to find a set of data that allows the prediction of material performance over a wide range of doping concentrations. Among the available data, a deep investigation of the reverse cross-relaxation process (F-3(4),F-3(4), -> H-3(6),H-3(4)) was not yet available. The numerical simulation indicates that the reverse cross-relaxation process parameter can be calculated by fitting the slow decaying H-3(4) fluorescence tails emitted when the pump level is almost depopulated. We also show that the floor of the H-3(4) decay curve is indeed related to a second exponential constant, half the F-3(4) lifetime, kicking in once the H-3(4) level depopulates. By properly fitting the whole set of decay curves for all samples, the proposed value for the reverse cross-relaxation process is 0.03 times the cross-relaxation parameter. We also comment on the measurement accuracy and best set-up. Excellent agreement was found between the simulated and experimental data, indicating the validity of the approach. This paper therefore proposes a set of parameters validated by fitting experimental fluorescence decay curves of both the H-3(4) and F-3(4) levels. To the best of our knowledge, this is the first time a numerical simulation has been able to predict the fluorescence behavior of glasses with doping levels ranging from 0.36 mol% to 10 mol%. We also show that appropriate calculations of the reverse cross-relaxation parameter may have a significant effect on the simulation of laser and amplifier devices. (C) 2017 Optical Society of America