Ultra-fast and accurate multimode waveguide design based on dataset-based eigenmode expansion method

Abstract: We propose a dataset-based photonic simulation framework for multimode waveguide design, enabling ultra-fast simulations with high accuracy. Compared to conventional approaches, our method offers two to three orders of magnitude speed-up in complex multimode waveguide designs. Based on this approach, we demonstrate a silicon multimode waveguide bend with an effective radius of $30\,\mu\mathrm{m}$ under one second, with accuracy validated against commercial 3D finite-difference time-domain method. We further explore its utility for device optimization by designing a $20\,\mu \mathrm{m}$-radius, arbitrary power splitting ratio bends through thousands of optimization iterations, completed in just 68 minutes on a standard desktop CPU. This framework enables the rapid design and engineering of large-scale multimode photonic devices, making computationally intensive simulations more accessible to many photonic circuit designers.