Power transients in hybrid optical amplifier (EDFA + DFRA) cascades

WRONs often involve channel drop/add procedures affecting the transmission quality due to the introduction of power excursions by the optical amplifiers. In this work, the Hybrid Amplifier (HA) transient response under WDM channel drop/add scenarios is analyzed by means of numerical simulation. When 17 out of 20 channels are dropped/added, the HA transient response is larger and faster for forward DFRA hybrid configurations. Two different reactions were identified: initial disturbances and steady state regions, both intensified by a cascade of 12 HAs. The amplifier's relative location determines power excursions up to the third amplification stage, being larger for “DFRA+ EDFA” configurations. For the “backward DFRA+EDFA” configuration, 6.41 dB to 8.45dB overshoots between the second and the sixth amplification stages were observed and the steady state power excursion reached 7.83 dB. For the “forward DFRA+ EDFA” configuration a 7.75dB overshoot and a 7.98 dB steady state power excursion response in the fourth amplification stage were obtained.