Multichannel EDFA chain control: a comparison of two all-optical approaches

Several methods have been proposed for eliminating the unwanted dependence of gain on the number of channels in multiwavelength Er-doped fiber amplifiers (EDFA)s. Using a time-and spectrally resolved simulation, we compare two all-optical methods of stabilizing output power per channel in chains of saturated EDFAs with changing numbers of channels. Both use all optical feedback, but one requires modifying only the first EDFA in the chain while the other demands that all EDFAs be gain clamped. We find that both can be used successfully but that each imposes different constraints on the EDFAs and on the network.