Patent ID: 7343093

Claim:
An optical WDM ring network including at least two add/drop nodes including a first node and a second node, links of single optical fibers connected in series with each other, each link extending between two of the add/drop nodes and allowing bidirectional traffic between said two of the add/drop nodes on the single optical fiber of the link, the links being connected to form a single ring path so that the ring path includes only one optical fiber path, characterized by a switching element in the first node for switching, for protection purposes, signals from the first node to the second node to travel on a first segment of the ring path or to travel on a second, complementary segment of the ring path, the first node arranged to receive signals from the second node from that segment on which signals from the first node are switched to travel, and the second node arranged to issue signals into the ring path to travel on both the first and second segments, the second node comprising: a plurality of receivers, a plurality of transmitters, and non-wavelength selective transmitter couplers, each transmitter having a single one of the transmitter couplers connected to it for splitting signals issued by the transmitter in two shares, a first share arranged to travel along the first segment to the first node and a second share arranged to travel along the second segment to the first node, each of the transmitter couplers having first and second outputs, the first output of each transmitter coupler connected to an individual first add element, the first add elements connected in series with each other to combine the first shares of the signals issued by all of the transmitters to a combined signal arranged to travel along the first segment and the second output of each transmitter coupler connected to an individual second add element, the second add elements connected in series with each other to combine the second shares of the signals issued by all of the transmitters to a combined signal arranged to travel along the second segment.