Theoretical and experimental investigation of GaAs/GaAlAs and n/n⁺GaAs rib waveguides

GaAs/GaAlAs and n/n+ GaAs rib waveguides with large rib height have been analyzed using a variational technique. This numerical analysis method yields accurate solutions of the modal propagation constants and is capable of providing the modal field distribution. Modal effective indices and intensity distributions are presented for various waveguide geometries. A simple effective index method of analysis has also been investigated and its accuracy and range of applicability determined. Rib waveguides have been fabricated and the number of observed modes is compared with the number predicted using the variational and effective index methods.