High-capacity upgrade of a PON by means of wavelength-routers and WDM techniques

A concept for an all-optical wavelength division multiplexing (WDM) overlay on a passive optical network (PON) and its experimental verification is presented. The WDM overlay at 1.5 mu m is realised leaving the outside fibre plant and the operation of the existing PON at 1.3 mu m unaltered. Arrayed waveguide gratings (AWG) are used to establish a point to point connectivity via individual wavelength paths between central office (CO) and each optical network unit (ONU). To keep the remote node (RN) totally passive the AWG at the RN can be monitored from the central office.