Narrowband wavelength demultiplexer using weighted coupling vertical couplers

In this paper a four channel narrowband wavelength demultiplexer utilizing vertical directional coupler structures is proposed and investigated theoretically. Four ridge waveguides with different ridge width are vertically coupled to weakly guided strip-loaded waveguide which results in four different wavelengths filtered out in each ridge waveguide, In order to reduce the side lobes, the coupling coefficients are weighted by varying the offset of ridge waveguides from the center of strip into propagation direction