A wavelength-selective filter, such as a narrow bandpass filter, is used to filter both the input and output of an optical amplifier. The selected channel is amplified and can be re-combined with the other original channels or provided to another output, depending on amplifier configuration. In a particular...http://www.google.fr/patents/US6433924?utm_source=gb-gplus-shareBrevet US6433924 - Wavelength-selective optical amplifier
