Less than 0.19-dB transient gain excursion AGC-EDFA with digital control for 20-channel add/drop equivalent operation

We have developed a digitally controlled AGC-EDFA by combining an FF-controlled pump-LD and an FB-controlled VOA. An FPGA is used to finely tune the gain setting of the pump current with a wide dynamic range for input burst signals and to precisely configure the gain and cutoff bandwidth for the loop control of the VOA. We realized a gain excursion of less than 0.19 dB at the AGC-EDFA with the VOA for a 20-channel add/drop equivalent operation. We believe 0.19 dB to be the smallest value yet reported.