Patent ID: 6947670

Claim:
An add/drop arrangement capable of adding/dropping at least one optical channel of a wavelength division multiplexed (WDM) signal in a WDM ring network having a plurality of nodes connected over an optical fiber facility, the arrangement comprising: in at least one of the plurality of nodes a broadband optical coupler including a first input coupled to the optical fiber facility for receiving the WDM signal, a first output for passing a tapped first portion of optical signal power of the WDM signal, and a second output for passing a second portion of optical signal power of the WDM signal to the WDM ring network, a receiver coupled to the first output, the receiver capable of extracting at least one optical channel from the tapped first portion, and a transmitter coupled to a second input of the broadband optical coupler, the transmitter capable of supplying an optical channel to be added to the WDM signal; and in a single central node in the WDM ring network, a means for preventing re-circulation of an optical channel to substantially reduce interference between optical channels transported between any of the plurality of nodes in the WDM ring network, the means for preventing including a wavelength termination element operable to terminate a selected optical channel when the selected optical channel has already passed a node at which the selected optical channel was extracted.