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Wave-matching simulations of integrated optical coupler structures

One of the principal tasks of numerically simulating integrated optical devices is the accurate calculation of modal fields and propagation constants. Our recently proposed 'wave-matching-method' for dielectric waveguides with rectangular and piecewise constant refractive index profiles is based on expansions of the electromagnetic field into functions with harmonic and exponential dependence on the transverse coordinates. Local expansions for regions with constant permittivity are joined by minimizing a least squares expression for the remaining misfit at the discontinuity lines. For this paper the wave-matching analysis has been applied to a number of more complex structures: a conventional, deeply etched two-waveguide coupler, an ARROW- waveguide, a three dimensional four-waveguide coupler and three-waveguide coupler with multimode central rib (radiatively coupled waveguides). We have found good overall agreement where a direct comparison with published results is possible.