Protection of surviving channels in a cascade of pump-loss controlled gain-locked EDFAs

The authors present results of numerical analysis on transient gain respons e to channel addition/removal in a wavelength division multiplexed network comprising six erbium-doped fibre amplifiers (EDFAs) with a pump-loss contr olled gain-locking feedback loop. A large-signal numerical model which inco rporates time variation effects, downstream propagation of signal and pump and both downstream and upstream propagation of amplified spontaneous emiss ion (ASE) has been used for the analysis. It follows from the theoretical i nvestigation that the surviving channel power excursion at the end of a cas cade of six 20 dB gain EDFAs can be kept below 0.8 dB in the case of the ad dition/removal of 6 channels in an 8-channel multiwavelength system when th e pump power feedback parameters are appropriately selected.