Patent ID: 7218805

Claim:
An optical WDM network for flexible connections comprising: at least one fiber ring path for carrying light signals, and nodes connected in said at least one ring path and having transmit and receive sides arranged to transmit and receive respectively light signals carrying information in distinct wavelength channels, receiver units and transmitter units comprised in the nodes, at least one of the nodes comprising: at least one add filter connected in the fiber ring path for adding light signals from the transmitter units of said at least one of the nodes to the light signals in said at least one fiber ring path, an optical power splitter connected in said at least one fiber ring path, the optical power splitter tapping off a portion of the power of signals propagating in said at least one fiber ring path, the portion containing light signals in all wavelength channels incoming to said at least one of the nodes, a demultiplexer connected to receive the tapped-off portion from the optical power splitter in said at least one of the nodes and separating the signals of the wavelength channels comprised in said tapped-off portion from each other, and a selector connected to receive the separated signals of the wavelength channels from the demultiplexer and connected to the receiver units of said least one of the nodes for switching signals in selected ones of the wavelength channels to the receiver units so that each of the receiver units of said at least one of the nodes can be selected to receive signals of any one of all of the wavelength channels.