Results from detailed numerical analyses of the modal characteristics of large-cross-section silicon-on-insulator-based rib waveguides are presented. They highlight for the first time that satisfying widely used design criteria is not sufficient to ensure single-mode behavior. In particular, the geometries that the design formulas predict should be single-mode are shown to support higher order vertical modes that do not couple (leak) into the outer slab region and are thus low loss in nature. Fortunately, a wide range of practical rib geometries still remains for which the leakage loss of modes other than those of EH_00 and HE_00 is sufficiently high to make the waveguides effectively single mode for each polarization.
© 2004 IEEE
J. Lousteau, D. Furniss, A. B. Seddon, T. M. Benson, A. Vukovic, and P. Sewell, "The Single-Mode Condition for Silicon-on-Insulator Optical Rib Waveguides With Large Cross Section," J. Lightwave Technol. 22, 1923- (2004)