Single mode silicon-on-insulator rib waveguides offer a weak lateral confinement, which makes it difficult to design high-performance multimode interference couplers (MMIs) based on these waveguides. Here, a complete design procedure for single etch step MMIs with tapered rib access waveguides is presented, which yields low excess loss (0.1 dB) and good imbalance (0.02 dB). Furthermore, polarization dependence is low, and high fabrication tolerances are achieved, especially with respect to etch depth.
© 2008 IEEE
Robert Halir, I. Molina-Fernández, A. Ortega-Moñux, J. G. Wangüemert-Pérez, Dan-Xia Xu, Pavel Cheben, and Siegfried Janz, "A Design Procedure for High-Performance, Rib-Waveguide-Based Multimode Interference Couplers in Silicon-on-Insulator," J. Lightwave Technol. 26, 2928-2936 (2008)