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US 6,646,795 B1Granted
Optical amplifier
AssigneeNortel Networks Limited
InventorsKevan P Jones, Ian P McClean
Life of this patent
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AssigneeNortel Networks Limited
InventorsKevan P Jones, Ian P McClean
Estimating the term…
An optical amplifier for amplifying the channel signals of a WDM signal comprises an amplifier arrangement for amplifying a band of the channels. The amplifier arrangement comprises an amplifier (6) and a filter (8). The filter comprises 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. 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 band of channels. The filter can be tuned to the requirements of a particular sub-band, whilst identical filters can be used for each sub-band. This invention enables identical filters to be used, and gives good pump power efficiency, as the attenuation of each filter can be controlled to the desired level, thereby avoiding the need for large increases in pump power.
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 comprising
A method of providing gain-flattened amplification of at least two sub-bands of channels of an optical WDM signal, comprising:
A WDM optical communications system comprising a plurality of nodes, each node being provided for transmitting and/or receiving at least two sub-bands of the WDM channels each sub-band comprising 2 to 8 channels, each node including optical amplifier arrangements for amplifying at least two of the respective sub-bands of channels, each amplifier arrangement 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 filters can be tuned to provide gain flattening for the amplified sub-bands of channels.
Dependencies are inferred from the claim text.