Mode classification in cylindrical dielectric waveguides

We discuss an analytical approach which leads to a global scheme for mode classification in two- and three-layers step-profile cylindrical dielectric waveguides, based on the requirements of analytical continuity HE/spl rarr/TE and EH/spl rarr/TM in the limit such that the system under consideration becomes a circular metallic waveguide. Technically, HE and EH hybrid modes correspond to the two roots of the problem´s quadratic characteristic equation. It turns out that the mode designation has the universality in the sense that the equation obtainable from the root involving positive (negative) sign always describes HE (EH) mode.