I was wondering if there exist any good (accurate/fast/easy-to-use) open-source FEM solvers for 3D time-harmonic Maxwell's equations. I am looking to simulate systems a few wavelengths large in the X/Y dimensions and tens of wavelengths in the Z dimension, so relatively small-size problems. All my dielectrics are homogeneous and perfectly rectangular (boxes).
I did some searching online and found various mature open-source FEM packages, but they do not seem to support Maxwell. Any suggestions would be much appreciated!