Patent ID: 7437075

Claim:
A reconfigurable integrated planar lightwave add-drop (RPLAD) multiplexer having a plurality of add ports and a plurality of drop ports, said RPLAD arranged for use in a WDM optical communication system, said RPLAD comprising a cross-connect switch formed from an interconnected array of optical 1×2 switches, means for dropping a first plurality of WDM channels from an input WDM signal to desired ones of said plurality of drop ports by controlling said optical 1×2 switches forming said cross-connect switch, a passive optical power combiner having an output port and a plurality of input ports, wherein each input port is connected to a respective add port of the plurality of add ports; wherein a plurality of said RPLAD multiplexers are interconnected by dual transmission rings that operate in opposite directions; and wherein said drop ports each drop channels from the input WDM signal only on one of said transmission rings, and said add ports add channels via the passive power combiner, only to the other one of said transmission rings, such that the dropped channels are received at the RPLAD only from a prescribed direction only on one of the transmission rings, and the added channels are transmitted from the RPLAD back only toward said prescribed direction only on the other transmission ring.