Patent ID: 6646795
Filing Date: 2003-11-11
Classification: H04B,H04J

Abstract:
An optical amplifier for amplifying the channel signals of a WDM signal, for use in a system comprising a first multiplexer arrangement between at least one signal carrier carrying the WDM signal and a plurality of signal carriers each carrying a respective sub-band of channels comprising 2 to 8 channels, said amplifier comprisingat least first and second amplifier arrangements for amplifying respective first and second sub-bands of channels, the amplifier arrangements each comprising an amplifier and a filter for filtering the respective sub-band of channels, the filter comprising a controllable optical filter having an attenuation characteristic which comprises a region of positive gradient and a region of negative gradient with respect to input frequency, wherein the magnitude and alignment along the frequency axis of the attenuation characteristic is variable, such that the filter can be tuned to provide gain flattening for the amplified sub-band of channels.