Patent ID: 7106969

Claim:
A wave division multiplexed (WDM) optical ring network, comprising: a plurality of nodes coupled to form an optical ring, wherein a portion of said nodes employs one or more optical amplifiers that add unwanted noise to an optical signal, said optical signal including in-use channels and unused channels whereby said unused channels potentially circulate said accumulated noise infinitely around said optical ring; an optical network terminator for removing said noise accumulation from said optical signal, wherein said optical network terminator comprises: an optical demultiplexer operative to demultiplex said WDM optical signal into a plurality of optical channels having different wavelengths including in-use channels and unused channels; means for attenuating said unused channels thereby preventing the infinite circulation of noise accumulation around said optical ring; a plurality of monitors, each monitor coupled in-line to an optical channel, said monitor operative to measure the optical power of a respective channel in response thereto, determine whether a channel is in-use or unused; and an optical multiplexer optically coupled to the output of said plurality of monitors, said optical multiplexer operative to multiplex said optical channels to generate an output optical signal therefrom with noise accumulation removed.