A multiplexing/demultiplexing optical circuit provides a demultiplexed output spectrum of channels having a flat amplitude response without sacrificing optical power. A phased array implementation and a diffraction grating implementation both rely on a first dispersion of the beam to be demultiplexed...http://www.google.com/patents/US6381052?utm_source=gb-gplus-sharePatent US6381052 - Multiplexors with a flat top spectral channel shape
