Signal restoration and BER performance of perturbed terrestrial cascaded EDFA systems

Signal restoration and bit-error-rate (BER) performance of perturbed terrestrial cascaded erbium-doped fiber amplifier (EDFA) systems is analyzed after the introduction of a normalized and revised EDFA gain formula. Results show that the total optical power can restore to 90 percent of its unperturbed value within 3 stages when the system suffers a 3 dB EDFA output power dip. The corresponding system BER will be impaired by more than one order of magnitude. EDFAs working under deeper saturation or having steeper saturation characteristic would result in smaller BER impairment under the same perturbation condition.