Analysis of dynamic pump-loss controlled gain-locking system for erbium-doped fiber amplifiers

Amplified multiwavelength optical communication networks are prone to substantial cross-gain modulation induced signal power fluctuations when channels are turned on/off or rerouted. This perturbs amplifier gains at other wavelengths and can cause service impairment not known in electronically switched networks. In this letter, we analyze the recently proposed and experimentally tested inversion and gain-locking technique for erbium-doped fiber amplifiers (EDFAs), based on pump power loss monitoring. A large-signal numerical model which incorporates time variation effects, the downstream propagation of signal and pump and both the downstream and upstream propagation of amplified spontaneous emission has been used for the analysis. 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 in case of addition/removal of six channels in an eight-channel multiwavelength system when the pump power feedback parameters are appropriately selected.