Geometrically modified multimode interference waveguides using high refractive index SiON material, for application in wavelength multiplexing/demultiplexing

Wavelength multiplexing/demultiplexing devices are considered to be one of the key elements in optical networks. Here we propose a new class of wavelength MUX/DEMUX devices which are based on change in the geometry of the multimode interference (MMI) waveguide region. This modification enables us to optimize device performances for a given set of refractive indices of core and cladding. The material of choice is SiON since it has an excellent surface morphology for the optical device application and its index of refraction can be varied from as low as 1.45 to as high as 2.5. A few designs for compact wavelength MUX/DEMUX based on off-center-fed excitement in geometrically modified MMI (GMM) are presented. Results show that modification in geometry of MMI device will lead to the better performances relative to simple MMI devices.