Analysis of buried-channel waveguides and couplers: scalar solution and polarization correction

Buried-channel waveguides and couplers are analyzed by perturbations and variational methods under the scalar approximation. Propagation constants of the first- and higher-order modes are calculated. When far from cutoff, both methods give nearly identical results. Near cutoff, the variational method predicts the dispersion characteristics more accurately. The methods can be easily implemented on a PC to produce the dispersion characteristics as well as the field patterns. Correction to the scalar solutions that accounts for the polarization effects due to the refractive index discontinuity and the material birefringence is included in the analysis.