Transient link control technique applied to optical hybrid amplifier (EDFA+DFRA) cascades

For the first time to our knowledge, power transient control in hybrid amplifier (HA) cascades is analyzed by means of numerical simulation. Four hybrid configurations are investigated, considering distributed fiber Raman amplifiers (DFRAs) in both backward and forward pumping schemes, in front of and behind an erbium doped fiber amplifier (EDFA). The link control technique was applied to the best and the worst configurations in terms of power excursion. When 17 out of 20 channels were dropped/added, the steady-state power excursions of the surviving channels were reduced from 4.21 dB and 6.25 dB to 0.01 dB and 0 dB, for a single HA under configurations EDFA + backward DFRA and forward DFRA + EDFA, respectively. For a cascade of 12 HAs (1800 km), the steady-state output power excursions were mitigated from 8.66 dB to 0.07 dB and 0.60 dB, for the same hybrid configurations, respectively.