Abstract: An integrated WDM device is provided by replacing fiber routing with a birefringent routing element, e.g. a rutile crystal. The device has a routing block for directing an incoming polarized light beam launched into its input port in one of two directions in dependence upon the polarization state of the light beam. A plurality of thin film filter (TFF) elements is provided in a zig-zag pattern on both faces of the routing block for filtering specific wavelengths of the beam. A rotator is provided for rotating the polarization of a portion of the beam so that it follows a separate path after reflection from the optical filter element, the path corresponding to the zig-zag arrangement of the TFF elements. If the incoming beam is non-polarized, polarization diversity elements are disposed in the optical path of the beam to control the polarization. The device may function as a WDM or as an add/drop multiplexer/demultiplexer.