Modeling gain dynamics in EDFAs: Space-resolved versus lumped models

We present a detailed comparison of dynamic space- and frequency-resolved a nd lumped erbium-doped fiber amplifier (EDFA) models. The space- and freque ncy-resolved models are based on an iterative solution of propagation equat ions for pump, multiple signals, and spectral components of forward and bac kward propagating amplified spontaneous powers and rate equations for pump, metastable, and ground energy level population densities of erbium ion. In contrast to space- resolved models, the lumped model solves a single ordin ary differential equation for time evolution of the length-averaged metasta ble level population and is therefore substantially less computer time cons uming. Both the space, and frequency-resolved and the lumped models give al most identical results when used for an analysis of surviving channel power excursions in concatenated EDFAs fed by multiwavelength signal and add/dro p scenarios. For a statistical analysis of output power and signal-to-noise ratio fluctuations in EDFA cascades fed by burst-mode packet traffic, only lumped models can be used.