The Performance of an EDFA in a Long Distance WDM Optical Network

In this paper, a simple mathematical model has been evaluated for an optical link constitute with a single mode fiber (SMF), a dispersion compensating fiber (DCF) and Erbium doped fiber amplifier (EDFA). The model allows us to perspecte the tolerance by which the channel signal power level passing through a cascade of (SMF+DCF+EDFA) may be driven into unacceptable regime of bit errors which means a distorted signal shape at the output of the link. The propagation of the multiplexed signal into the optical link was described by two differential equations. The first one describes the propagation on the (SMF+DCF) portion using the nonlinear Schrödinger equation (NLS) [1] which takes into account the linear effects such as the attenuation and dispersion effects, and the nonlinear effects such as the Kerr effect, Raman and Brillouin scattering. The second is the ordinary differential equation (ODE) proposed by Bononi et al [2] which describes the propagation of the signal in the (EDFA). The performance of the optical system under this mathematical model was investigate. Where we varied certain parameters such as the length of the link, the input signal power, the EDFA pump power, the doped fiber amplifier length and the modulation format (RZ/NRZ). The analysis justifies the accuracy that each component must have to ensure good reception of the signal at the end of the link.