A wavelength division multiplexed (WDM) apparatus is provided for a bidirectional
dense WDM optical fiber communication network with cost-effective and efficient
allocation of the resources available at each network node. For each fiber link,
the invention uses a WDM signal composed of channels propagating in opposite directions
and a band optical add-drop multiplexer (OADM) to isolate or combine a band to
the WDM signal spectrum. As a result, the invention significantly reduces the number
fiber connections and filtering equipment required with respect to each direction
of transmission.