Investigation of EDFA positioning impact on the quality of the amplified signal in DWDM transmission systems

Due to the all-time growing demand for higher network capacity, during recent years a lot effort was made not only to build new high performance optical transmission systems, but also to improve the operation of already existing systems. Optical amplifiers are such type of network elements the operation of which can severely impact the performance of a whole system. Many factors can impact the performance of an optical amplifier, but the most significant of them is the power of the input signal, which can be varied by changing the position of an amplifier in the optical link. Erbium doped fiber amplifiers (EDFA) are the most commonly used type of amplifiers in modern optical transmission systems. This is why in this research the authors investigate the impact of EDFA positioning in a dense wavelength-division multiplexed transmission system (DWDM) on the quality of the amplified signal, aiming to improve the performance of EDFAs in existing WDM transmission systems. Three different scenarios were considered: when the EDFA was used as a power booster, as an in-line amplifier and as a preamplifier. In all three cases such EDFA configurations were obtained that could ensure the required quality of the signal by using as low pump power as possible.