A system for a re-configurable optical de-multiplexer, multiplexer or add/drop multiplexer is provided. A re-configurable de-multiplexer system comprises a wavelength selective switch having an input port, an output port and an internal port; a wavelength division de-multiplexer (WDM) optically coupled to the internal port and a plurality of dropped-channel ports optically coupled to the WDM. The wavelength selective switch receives a plurality of input wavelength-division multiplexed channels from the input port and routes a first subset of the channels to the output port and a second subset of channels to the internal port and then to the WDM. The WDM separates each of the dropped channels to a different respective one of the channel ports.