Investigation of amplification span length impact on the quality of the signal in WDM transmission systems with erbium-doped fiber amplifiers

In this research the authors investigate the impact of the length of the amplification span on the quality of the signal in a wavelength division multiplexing (WDM) transmission system with erbium-doped fiber amplifiers (EDFAs). During the research 3 different amplification spans were used in a 16 channel WDM system with total transmission distance of 300 km: 75 km, 100 km and 150 km, with an EDFA at the end of each span. In all three cases the configuration of the EDFAs were chosen in a way to ensure the required quality of the signal by using as low pump power and as short erbium-doped fiber (EDF) as possible. To evaluate the quality of the amplified signal, the dependences of maximal bit error ratio(BER) values among all the channels on the power of the detected signal was obtained for each length of amplification span. These results were used to obtain power penalty in respect to a 16 channel WDM system without amplification.