Comparison of discrete and distributed in-line Raman amplifiers in a 16 channel DWDM transmission system

The main goal of this paper is to investigate and compare the performance of an in-line distributed Raman amplifier (DRA) and an in-line lumped Raman amplifier (LRA) in a 16 channel DWDM transmission system in the case with counter-propagating pumping configuration. The comparison was made for different values of input signal power which was controlled by changing the positioning of the amplifier in the 150 km long optical link. Three different scenarios were observed - when the LRA or the pump of the DRA were placed 75 km, 100 km and 125 km away from the transmitter block. At each value of input signal power, the main criteria set by the authors was to find and compare the minimal pump power for the DRA and the LRA that would ensure bit-error ratio below the 1 · 10
^-9
threshold in all channels.