Erbium-Doped Fiber Amplifier Spectral Behavior in Transoceanic Links,

Some experiments have already been presented for long haul transmission using in-line Erbium-Doped Fiber, Amplifiers EDFA 1,2. However, the question is to determine the actual system limitations for transoceanic links up to 10,000 km, such as EDFA maximum output power, amplifier spacing, optical filter design. Some theoretical 3 and experimental 41 works have been published mainly with a recirculating loop. A specific problem is to predict the evolution of signal and Amplified Spontaneous Emission ASE powers along the link. To our knowledge, the calculations published so far have assumed that an optical filter was set after each amplifier. In this case, the cascaded EDFA behavior can be described by scalar values without spectral dependence, and an analytical calculation is possible. In order to predict the cascaded EDFA behavior in a more general case, spectral characteristics have to be considered, especially if there is no optical filter after each amplifier. The subject of this paper is to examine these specific aspects without taking into account the dispersive and non linear effects. Calculations for very long links are presented along with an experimental validation of the modeling.