| 摘要 |
The invention relates to a multistage fibre amplifier having a first amplifying fibre (EDFI) and at least one further amplifying fibre (EDF2) connected in series, and also a pump source (2D), a first pump signal (AI) being fed to the first amplifying fibre (EDFI) and a further pump signal (A2) being fed to the further amplifying fibre (EDF2). The multistage fibre amplifier is distinguished by the fact that the further pump signal (A2) is fed to the further amplifying fibre (EDF2) via a power-dependent attenuation element (ZFED). The attenuation element (ZFED) is formed in such a way that, as the pump power increases, small further pump signals are attenuated to a greater extent than large further pump signals. The power-dependent attenuation of the pump signal (A2) fed to the further amplifying fibre primarily results in improvements in the noise figure of the multistage amplifier. A method for adapting the pump power of the multistage fibre amplifier according to the invention is furthermore specified. This involves a modified feedforward control which advantageously compensates for the delays brought about by the additional fibre on changes in the input signal power. An improved dynamic behaviour of the multistage fibre amplifier is achieved by means of the method according to the invention. |
