Check oblique planewave source in 3D with rotation matrix

[vumiRa6]

Hello,

I'm trying to set up an oblique plane wave in 3D with arbitrary polarisation. I've read the relevant discussions:

• https://meep.readthedocs.io/en/master/FAQ/#how-do-i-create-an-oblique-planewave-source
• Planewave in 3D model #2589
• off-normal sources with periodic boundary conditions #2293
• https://meep.readthedocs.io/en/latest/Python_Tutorials/Mode_Decomposition/#reflectance-and-transmittance-spectra-for-planewave-at-oblique-incidence

but I'm dissatisfied with the results and suspect that I'm missing something fundamental.

In the following example (code attached below), I have a plane wave propagating along si with circular polarization. Using the rotation matrix R, I can transform back the electric field into the wave's rotated frame of reference where I would expect Ez = 0 everywhere in the cell. Instead, there's a large portion of the cell where Ez is not negligible.

Should I not expect to zero out Ez in the wave frame of reference (si aligned to z)? Or am I misunderstanding how amp_func should be used?

rotate_plane_wave.py

[dinelanthony]

Could there be some kind of alignment issue? If we are assuming Si is normal to your monitor the Ex and Ey, shouldn't their profiles be identical for circular polarization?