We propose an energy transfer model with a cubic atomic population dependence
to accurately model the behavior of various reported high-power erbium-doped
fluoride fiber lasers operating near 2.8 microns. We first show that the
previously introduced weakly interacting (WI) and strongly interacting (SI)
models are not adequate for precisely modeling such high-power erbium-doped
fluoride fiber lasers. We compare results obtained with the WI and SI models to
the proposed model by simulating 4 different highly doped (7 mol.%) fiber
lasers previously reported in the literature. Laser efficiencies and powers are
reproduced with great accuracy. In addition, four other independent fiber laser
systems based on erbium doping concentrations varying from 1-6 mol.% are also
simulated with good accuracy using the proposed model with the exact same set
of spectroscopic parameters, which confirms its validity for various erbium
doping concentrations. Redshifting of laser wavelength is also taken into
account by considering the full cross section spectra and computing signal
powers over several wavelength channels.Comment: 9 pages, 18 figures, submitted to IEEE Journal of Quantum Electronic