§ free browser tool
Online Waveguide Mode Solver (FDE)
Full-vectorial finite-difference eigenmode solving - no license, no cloud, no signup.
Launch the tool →A full-vectorial FDE mode solver implementing the Zhu & Brown (2002) finite-difference formulation - the same published algorithm commercial eigenmode solvers build on - running entirely in your browser inside a Web Worker. Build an arbitrary cross-section from rectangles and ellipses (sidewall angles supported), pick mesh, wavelength, and boundary conditions, and solve for guided modes with effective index, TE polarization fraction, and full field profiles.
Materials are dispersive: built-in Sellmeier models for Si, SiO2, Si3N4, sapphire, and X-cut lithium niobate (with proper per-axis anisotropy), tabulated films fetched live from the public-domain refractiveindex.info database, or your own constant, anisotropic, or Sellmeier models. Every model's coefficients and source citation are inspectable in the UI.
Parameter sweeps cover any geometry dimension or the wavelength, with Lumerical-style mode tracking: select modes after a solve and the sweep follows them by field overlap, so mode identity survives TE/TM crossings. Results export to CSV.
The solver is validated against a published FEM benchmark (effective indices agree to ~1e-3 at 20 nm mesh) and against analytic fiber theory for the SMF-28 preset. Presets include SOI strip and rib, silicon nitride, slot waveguides, thin-film lithium niobate ridge, and standard single-mode fiber.
Features
- ▸Full-vectorial FDE (Zhu & Brown 2002) with index averaging at interfaces
- ▸Arbitrary stacks: rectangles + ellipses, sidewall angles, no hardcoded geometry
- ▸Dispersive materials incl. anisotropic LiNbO3; live refractiveindex.info fetching
- ▸n_eff, TE fraction, Ex/Ey/Ez field plots; PEC/PMC boundaries; mesh control
- ▸Parameter sweeps with overlap-based mode tracking and CSV export
- ▸Runs in a Web Worker on your machine - free, private, no account