Patent ID: 6498677
Filing Date: 2002-12-24
Classification: H04B

Abstract:
A method for controlling gain transients in a rare-earth-doped fiber amplifier with a non-flat gain spectrum, wherein the rare-earth-doped fiber amplifier has rare-earth-doped fiber that is pumped using a pump laser to produce a gain spectrum so that optical signals that are provided to an input are amplified and provided as corresponding amplified optical signals at an output, comprising:tapping the optical signals at the input and the output of the amplifier; measuring a modified gain for the amplifier by spectrally-filtering at least some of the optical signals and at least partly using the spectrally filtered optical signals to calculate the modified gain; and adjusting the pump power produced by the pump laser using a feedback control technique that maintains the modified gain at a constant value, wherein measuring the modified gain comprises spectrally filtering the tapped optical signals at the amplifier output using a spectral filter with a transmission spectrum that is inversely proportional to the non-flat gain spectrum.