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Two asymmetrical optical rib waveguides

The propagation characteristics of the structure consisting of two asymmetrical optical rib waveguides, which are fabricated on a common substrate, are investigated. The dependence of the coupling length and the number of the guided supermodes on the structure dimensions, wavelength and polarisation are studied. The application of the analysed structure as an optical directional coupler is discussed. The analysis is carried out using the Semivectorial Finite Difference Method while the eigenvalue problem is solved using iterative methods.