A method for calculating the guided modes of strip-loaded optical waveguides with arbitrary index profile

The characteristics of planar strip-loaded optical waveguides are investigated by a semianalytical method. In the coordinate direction of constant permittivity the electromagnetic fields are expressed analytically, whereas in the direction of arbitrary permittivity distribution a pointwise description of the fields is chosen. For different approximations of permittivity profile, such as the exponential and the stepped profile, the propagation constants and the main field components are calculated and compared to corresponding results from literature. As the method presented is highly adapted to the physical problem, accurate results are obtained with small computational effort.