Patent ID: 7088496

Claim:
A method for controlling a pump device of a fiber amplifier for amplification of a transmitted wavelength division multiplex signal, comprising a first pump source, the pump signal of which operates in an input area of the fiber amplifier, and with a second pump source, the pump signal of which operates in a further area of the fiber amplifier, wherein an actual power of the wavelength division multiplex signal is determined at the output of the fiber amplifier and the output powers of the two pump sources are controlled in order to adjust a noise figure of the amplified wavelength division multiplex signal, wherein for a total pump power varying over a total pump power range according to the number of active channels, the determined actual power of the wavelength division multiplex signal is compared with a reference power and wherein a required total pump power P tot is set and wherein in order to adjust a noise figure of the wavelength division multiplex signal, the output powers of the two pump sources are set as a function of the total pump power P tot such that in the fiber amplifier, at a lower total pump power P tot of the power range, a higher inversion is produced by the first pump source and a lower inversion is produced by the second pump source, and that with increasing total pump power P tot the pump power of the first pump source initially increases at a higher rate of increase and after initially increasing, subsequently increasing at a lower rate of increase than the pump power of the second pump source.