Hmm I was trying to efficiently compute contribution from a periodic cylinder structure and avoid the expensive spatial sum used in MEEP. I don’t think this functionality was implemented MEEP currently.
On Sun, Nov 8, 2020 at 9:36 PM Ardavan Oskooi <ardavan.osk...@gmail.com> wrote: > For reference, note that the near2far feature already exists for > cylindrical coordinates. It was added in > https://github.com/NanoComp/meep/pull/1090. (This implementation is based > on integrating over φ using green3d.) For a demonstration, see this tutorial > example > <https://meep.readthedocs.io/en/latest/Python_Tutorials/Cylindrical_Coordinates/#focusing-properties-of-a-binary-phase-zone-plate> > . > On 11/8/20 16:47, Mandy Xia wrote: > > In my problem, I have a periodic cylinder structure along z-direction and > I would like to compute the scattered field in the far field. Using the > spectral representation of PGF, I'm able to compute, for a particular point > in the simulated period, what the total contribution summing over all the > period is, without an expensive spatial sum. In order to collect all the > contributions from the cylinder, the last step I need is to integrate over > the simulated period and I was trying to rely on the numerical integration > over near-field box in MEEP to handle that. However, I found that the > computed results are off. I suspected this was due to the staggered grid we > are using. I examined the coordinates of the discrete points on the near > field box. For some (x, y) combinations, we have z coordinates going from > -period/2 to period/2 in z and in total an odd number of points. In some > other (x, y) combinations, we have z coordinates going from > -period/2+half_cell to period/2-half_cell and in total an even number of > points. So it seems that in the above two scenarios we are integrating over > different lengths in z. However, in order to get the correct contribution, > I need to integrate over exactly one period of the structure. I'm wondering > if you have any suggestions on this. Or maybe there is something wrong with > my understanding of the staggered grid, and it would be great if you could > point it out. > >
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