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

This advanced tutorial guides you through estimating the insertion loss of a D-shaped single-mode optical fiber at different polishing depths using COMSOL Multiphysics v5.6 and Microsoft Excel. Building on the foundational D-shaped optical fiber modelling and simulation workflow, this tutorial extends the analysis to estimate insertion loss through eigenmode analysis, vectorial modal-overlap calculations, complex modal propagation, and a parametric sweep. The simulation results are then processed in Microsoft Excel to calculate normalized transmission and generate an insertion-loss-versus-polishing-depth plot. What You Will Learn - Perform eigenmode analysis of a D-shaped optical fiber. - Set up a parametric sweep across varying polishing depths. - Calculate modal overlap coefficients using the adopted vectorial field-overlap approach. - Process simulation results in Microsoft Excel, including coherent summation of complex modal contributions. - Calculate normalized transmission and estimate insertion loss at each polishing depth. - Plot and interpret the relationship between polishing depth and estimated insertion loss. Prerequisite Tutorial Please complete the following foundational tutorial before proceeding with this advanced tutorial: "COMSOL Multiphysics Tutorial: D-Shaped Optical Fiber Modelling and Simulation" The previous tutorial covers the foundational modelling and simulation setup required for this advanced workflow. Familiarity with the original model structure and COMSOL settings is recommended. Software Requirements - COMSOL Multiphysics v5.6 with the Wave Optics Module. - Microsoft Excel for post-processing simulation results. Important Note This tutorial uses a reduced-order modelling approach to estimate insertion loss. It does not represent a complete three-dimensional longitudinal simulation of the optical fiber. The estimates are subject to the modelling assumptions and limitations described in the tutorial. Intended Audience Suitable for Master's and PhD students, postgraduate researchers, and others interested in optical-fiber modelling and simulation using COMSOL Multiphysics. Copyright and Usage Terms Copyright © 2026 Ahmad Zarif Zulkifli. All rights reserved. This tutorial is provided for educational and individual learning purposes only. Users may apply the methods described in this tutorial in their own simulations and research, and publish their independently obtained results, subject to applicable copyright laws, software licence terms, and relevant academic citation requirements. Reproduction or redistribution of this tutorial's original content without the author's prior written permission is prohibited, except as permitted by applicable law. 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.