A (de)multiplexer for use in optical communications systems for multiplexing and demultiplexing an optical signal consisting of optical channel(s) of different wavelength(s) includes a multiplex optical waveguide propagating a plurality of optical channels and a plurality of single channel optical waveguides,...http://www.google.com/patents/US6754412?utm_source=gb-gplus-sharePatent US6754412 - Apparatus and method for producing a flat-topped filter response for (de)multiplexer having a diffraction grating with variable line spacing
