Modelling of a pump-power-loss-controlled gain-locking system for EDFA application in WDM transmission systems

Transient-gain amplifiers to represents a major problem in multiwavelength optical networks. To avoid error bursts in the surviving channels, signal-power fluctuations due to channel addition or removal caused by network reconfigurations or line failures must be minimised. The recently proposed and experimentally tested inversion and gain-locking technique for erbium-doped fibre amplifiers (EDFAs), based on pump power loss monitoring, is analysed. The analysis is based on the of a comprehensive large-signal model which incorporates temporal the downstream and propagation of signal, pump and spontaneous emission (ASE) in an erbium-doped fibre amplifier. It follows from the theoretical investigation that the surviving channel-power excursion in a single 20 dB gain EDFA can be reduced to 0.3 dB through the addition/removal of six channels in an eight-channel multiwavelength system when the pump-power-feedback parameters are appropriately selected