Comparison of normal mode and total field analysis techniques in planar integrated optics

Normal mode and total field analysis techniques for calculating the fields generated by a polarization source are discussed. The amplitudes of the normal modes are evaluated using a Green’s-function approach and the results are compared to a previous treatment by Yariv. The generated fields are also calculated by solving the polarization driven wave equation subject to the usual electromagnetic boundary conditions at all of the pertinent interfaces. It is shown that these two approaches yield equivalent results for a simple case, and their relative merits for solving problems in different regions of a waveguide are discussed.