Accurately extracting silicon waveguide dimensions from a single high-order Mach-Zehnder Interferometer

We experimentally demonstrate a new methodology for the extraction of dimensions from silicon-on-insulator (SOI) strip waveguides manufactured in IMEC's iSiPP50G silicon photonics platform. The effective index (<i>n</i>_<i>eff</i>) and group index (<i>n</i>_<i>g</i>) of the waveguide are determined from the spectral data of a single high-order Mach-Zehnder Interferometer (MZI). In this study, we introduce an innovative mapping model that effectively relates the geometric dimensions of the SOI waveguide to its <i>n</i>_<i>eff</i> and <i>n</i>_<i>g</i>, thereby enhancing mapping accuracy and reducing model complexity. Furthermore, we will elucidate the feasibility and constraints for extracting <i>n</i>_<i>eff</i> and <i>n</i>_<i>g</i> through the optical transmission measurement of only a single high-order MZI. Our analysis also addresses the parameter extraction errors that have a significant impact on the results, which have not been previously discussed in the literature.