MODELING OF A PUMP-POWER-LOSS-CONTROLLED GAIN-LOCKING SYSTEM FOR EDFAAPPLICATION IN WDM TRANSMISSION-SYSTEMS

Transient-gain response of optical amplifiers to addition/removal of c hannels represents a major problem in multiwavelength optical networks . To avoid error bursts in the surviving channels, signal-power fluctu ations due to channel addition or removal caused by network reconfigur ations or line failures must be minimised. The recently proposed and e xperimentally tested inversion and gain-locking technique for erbium-d oped fibre amplifiers (EDFAs), based on pump power loss monitoring, is analysed. The analysis is based on the application of a comprehensive large-signal numerical model which incorporates temporal properties a nd the downstream and upstream propagation of signal, pump and spontan eous emission (ASE) in an erbium-doped fibre amplifier. It follows fro m the theoretical investigation that the surviving channel-power excur sion 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 s ystem when the pump-power-feedback parameters are appropriately select ed.