A full-vectorial pseudospectral modal analysis of dielectric optical waveguides with stepped refractive index profiles

A new full-vectorial mode solver based on the pseudospectral method for computing dielectric optical waveguides is proposed. The subdomains with homogeneous refractive indexes are connected with imposing the continuities of E-z and H-z at the dielectric interfaces, and thus the coupled equations in terms of the transverse magnetic field components H-x and H-y are formulated. The optical fields are expanded by a suitable set of orthogonal basis functions, such as Laguerre-Gauss (LG) functions or Chebyshev polynomials. Furthermore, the a priori determination of the scaling factor in LG functions is introduced by means of the effective index method in order to considerably reduce the extra computational time by lengthy trial and errors used by others. Results calculated by the proposed full-vectorial scheme for dispersion characteristics of rectangular channel and rib waveguides having piecewise uniform refractive indexes, even though a coarse mesh used, show good agreement with previously published data based on other rigorous numerical methods.