Grating-assisted coupling of highly asymmetric dielectric waveguides

Summary form only given. Coupling between two integrated waveguides, where one waveguide has a high effective index and the other a low effective index is of interest in the fabrication of wavelength-division multiplexed (WDM) sources, which can be easily coupled to optical fibers. This paper discusses a more accurate method for the calculation of the coupling problem for such highly asymmetric waveguides. The method is based on Floquet-Block modes and provides a rigorous electromagnetic solution of the grating-assisted directional couplers (GADC). The grating period and coupling length can be accurately predicted, even though the structure may have a strong grating, and the waveguides are highly dissimilar.