COMSOL Tutorial: Advanced Modelling and Simulation for Calculating Insertion Loss at Varying Polishing Depths of a D-shaped Optical Fiber

This step-by-step PDF tutorial guides you through an advanced modelling and simulation workflow for estimating insertion loss (IL) of a D-shaped single-mode optical fiber (SMF) at different polishing depths. Building on the foundational D-shaped optical fiber modelling tutorial, this guide introduces a reduced-order vectorial electromagnetic field-overlap approach to estimate coupling between the input single-mode fiber (SMF) field and the calculated modes of the polished fiber section. What You Will Learn: Set up and modify the D-shaped optical fiber geometry for varying polishing depths. Calculate the effective optical interaction length using a simplified geometric model. Calculate modal power using the longitudinal time-averaged Poynting flux. Estimate modal coupling coefficients using vectorial electromagnetic field-overlap integrals. Account for mode-specific power-normalization factors in the overlap calculations. Export simulation data from COMSOL Multiphysics v5.6 for further analysis in Microsoft Excel. Calculate transmission and estimate insertion loss (dB) as a function of polishing depth. Interpret the results and understand the assumptions and limitations of the adopted modelling approach. Who Is This Tutorial For? Suitable for research students, postgraduate researchers, and anyone interested in optical fiber modelling, electromagnetic simulation, and insertion-loss analysis. Prerequisites: Basic familiarity with COMSOL Multiphysics v5.6, Wave Optics Module, optical fiber fundamentals, advanced electromagnetic wave theory and Microsoft Excel is recommended. The foundational D-shaped optical fiber modelling tutorial is recommended as a starting point. What You Will Receive A downloadable PDF tutorial with step-by-step instructions. A practical workflow connecting COMSOL eigenmode calculations with Excel-based transmission and insertion-loss analysis. An explanation of the modelling assumptions, normalization approach, and interpretation of calculated results. Important Note: This tutorial presents a reduced-order modelling approach for estimating insertion loss. It does not explicitly model all three-dimensional transition effects, surface-roughness scattering, or every fabrication-related effect. Numerical results may vary with model settings and implementation. Software: COMSOL Multiphysics v5.6, Wave Optics Module, and Microsoft Excel. Format: Digital PDF download. Research Use: The methods may be applied to independent simulations and research, subject to applicable copyright laws, software licence terms, and academic citation requirements. Redistribution or reproduction of the tutorial itself is not permitted without the author's permission, except as permitted by applicable law. © 2026 Ahmad Zarif Zulkifli. All rights reserved. COMSOL Multiphysics is a registered trademark of COMSOL AB. This tutorial is an independent educational guide and is not affiliated with, endorsed by, or sponsored by COMSOL AB.