Calculating transfer and loss coefficients in bent slab single mode micro-waveguides and micro-rings considering bending and coupling losses

In this work, using boundary element numerical method, monochromatic wave propagation equation was solved in a bent micro-waveguide coupled with two direct waveguides. In the previous works, bent micro-waveguides have been generally considered by themselves without comparison with any direct waveguides; however, in this study, the bent waveguide was assumed to be connected to two direct waveguides at both ends. Transfer matrix was proposed in a multi-mode bent waveguide. Using the components of this matrix, loss coefficients were calculated. Results of modeling for the single-mode waveguide were compared with those from FDM method, which showed that the proposed method had higher accuracy and needed less time for calculation. Finally, by eliminating the effects of coupling, a model was presented for calculating loss coefficient in micro-rings and the behavior of loss coefficient was investigated in terms of radius and wavelength.