Integrated planar waveguide demultiplexers for high-density WDM applications

A review is presented of state-of-the-art optical planar waveguide demultip lexers (DEMUXes), that is, phasars (arrayed waveguide) and etched grating d evices designed for high-density (narrow channel spacing) wavelength divisi on multiplexing (WDM) systems. Their advantages and disadvantages are discu ssed in comparison with other techniques for demultiplexing WDM signals. Th e advances made in their performance are reviewed, and ultimate limitations set by technological constraints, are proposed Finally a comparison is mad e of the advantages and disadvantages of etched grating as opposed to phasa r planar waveguide DEMUXes.