Analysis of rib waveguides with sloped rib sides

Abstract

Using a mode matching technique, an approximate microwave equivalent circuit is developed for a dielectric step discontinuity in the transverse direction of a dielectric waveguide. Using this basic building block, rib waveguides with sloped sides are analyzed by approximating the actual rib profile with a staircase function, and cut-off conditions for E12 and E21 modes are calculated. The results of the theoretical analysis are verified with experiments performed on homojunction GaAs rib waveguides. Finally, an effective rib width appropriate for applying the results of analyses of ideal structures to sloped sided guides is identified.