Does anyone know of a good open-source 2D field solver? If it can handle dielectric interfaces that would be ideal

(a) SNL Charon/Charon2 doc: https://charon.sandia.gov/documentation-tutorials/ src (login required) : https://charon.sandia.gov/sign-in/ (b) Genius (2D-version is opensource), src: https://github.com/cogenda/Genius-TCAD-Open (c) DevSim (python interface included) doc: https://zenodo.org/records/7779819 src: https://github.com/devsim/devsim Dockerfiles for the above TCADs: https://github.com/thesourcerer8/OpenSourceTCAD For a quick start, I recommend: DevSim (and for an open source mesher: https://gmsh.info/)

Thank very much for all the links. I'm thinking about building RC extraction models so layout cross sections are the main use case

I am the developer of DEVSIM, and it can certainly solve electrostatic problems. It is not setup for full wave E&M. There are some interesting examples here using Palace and Elmer: https://gdsfactory.github.io/gplugins/notebooks/elmer_01_electrostatic.html https://gdsfactory.github.io/gplugins/notebooks/palace_01_electrostatic.html https://gdsfactory.github.io/gplugins/notebooks/palace_02_fullwave.html The integration with gdsfactory may be well suited for the RC extraction use case.