Field projection for 2D sim or periodic sim in general

[tomflexcompute]

If I understand correctly our field projection at the moment only works with absorbing boundaries. If so, is it possible to add support for 2D simulations and periodic simulations in general? Priority for this is not high.

[momchil-flex]

Really missing Shash for this one.

Note that DiffractionMonitor is basically equivalent to the FieldProjectionAngleMonitor/FieldProjectionKSpaceMonitor for a plane covering the entire simulation domain with periodic boundaries with far_field_approx=True. So I think use cases that still need to be covered are (in order of decreasing priority imo):

• FieldProjectionCartesianMonitor with periodic boundaries
• periodic boundaries on one side but not the other, like a 2D sim with pml
• far_field_approx = False
• near field plane that does not span the full plane along the periodic direction (this seems like a weird setup)

Am I missing something?

[tomflexcompute]

Yeah that sounds very good.

[tomflexcompute]

Since the opening of this issue, a number of users have asked about field projection for 2D sims. The use cases include the initial design of grating couplers in 2D and finite diffractive gratings that are translation invariant in one dimension.

Bumping the priority of this issue up a bit but it's fine if it's going to take some time.

[momchil-flex]

Ok, noted about higher priority, but it will still take some time.