Guidelines for amplification of optical packets in WDM environment regarding impact of transient response of erbium-doped fiber amplifier

We investigated the impaired amplification of optical packets by using erbium-doped fiber amplifiers (EDFAs) in several distinctive cases in a WDM environment. The origin of the impairment was mainly gain excursion caused by cross gain saturation and additional noise coming from interchannel crosstalk in WDM. The degree of impairment changed according to traffic density. Moreover, the impairment was cumulative with an increase in the number of EDFAs cascaded, resulting in substantially reduced error tolerance in the optical packet-receiver according to the traffic density and the number of hops each packet experienced. We confirmed that our previously proposed mitigation approach adopting a special class of erbium-doped fiber (EDF) with a larger active erbium core was also effective in the WDM environment. Our approach can supplement the conventional electrical gain control used to correct for the transient responses which result in insufficient response speed in applications involving sub-microsecond optical packets. Finally, we discuss desirable traffic conditions as guidelines for amplification of optical packets.