Gain control in EDFA's by pump compensation

Gain control by means of pump compensation in cascades of erbium-doped fiber amplifiers (EDFAs) is analyzed. Based on analytical expressions for the 1-dB rise/fall time for the case of channels add/drop, required pump power changes at each amplifier are derived in the form of simple closed expressions. Numerical simulations of a system comprising 20 wavelength division-multiplexed channels transmitted through a cascade of 35 EDFAs are performed demonstrating the effectiveness of the gain control.