Model of temperature dependence for gain shape of erbium-doped fiber amplifier

The problem of modeling the temperature dependence of erbium-doped fiber amplifier (EDFAs) is important for multichannel optical WDM systems. A physical model is presented in this paper, which could be used to predict the gain change under temperature variations for such systems. Some of the input parameters for the model are the erbium energy sublevel density, excitation coefficients from lower sublevels to upper sublevels of erbium ions, and electron distribution over energy levels. It is difficult to measure these parameters. In order to use the model for gain shape calculations, some simplifications are demonstrated. These simplifications lead to two numerical models, which are shown to be consistent with experimental data with reasonable accuracy, and are based only on two spectral measurements for different temperatures. Both numerical models were tested for the signal band and the 980 nm pump band of a typical erbium-doped fiber.