AWG based WDM upgrade of a PON

An all-optical passive WDM upgrade of a passive optical network (PON) is proposed. By means of 1.3/1.5 /spl mu/m splitters the upgrade enables additional operation in the 1.5 /spl mu/m window without disturbing the operation at 1.3 /spl mu/m. The outside fiber plant remains unmodified. Key components of the upgrade are arrayed waveguide gratings (AWGs) in the remote node (RN) and in the central office (CO).