title: Theoretical modeling of erbium-doped fiber amplifiers with excited-state absorption.
abstract: Numerical solution of a general rate-equation model of an erbium-doped fiber amplifier highlights several important features of the device. A difference in strong-signal gain between copropagating and counterpropagating signal pump schemes in the presence of pump excited-state absorption is predicted, and this is confirmed by experimen. The detriment in the noise figure previously associated with counterpropagating schemes for only small-signal conditions is shown to be similar for strong signals, corresponding to a power-amplifier operating regime. In addition, a correction to the noise figure is given for the limit of a low-gain amplifier.
authors.forename: P R
authors.initials: PR
authors.lastname: Morkel
authors.forename: R I
authors.initials: RI
authors.lastname: Laming