Thanks, but it seems like this doesn't change much. I turned off
subpixel averaging, increased the resolution to 100, and also increased
the PML thickness to 1.2 (=max wavelength). I have run so far for 1800
time units. At 25 time units, the field decay was 0.0090 whereas at 1725
time units the field decay is 0.0433 (and some absorption values are
negative). I get the same problem if I replace the sidewall-angle-Prism
pyramid with a set of Block objects to approximate a pyramid.
On 2020-07-30 9:46 p.m., Ardavan Oskooi wrote:
Try turning off subpixel averaging since it sometimes causes
instabilities with the prism sidewall angle feature. This means that
you will also need to increase the resolution.
On 7/29/20 16:38, J. Philip Haupt wrote:
I get that the fields diverge (albeit very slowly), at least so it
seems. Boundary conditions are k_point=Vector3(0,0,0) with PML in the
Z direction. My guess has been that the pyramid reflects light such
that it hits the PML at a glancing angle and this gives reflective
artefacts. I've hence played with PML parameters (thickness, profile,
R_asymptotic) and the distance between sources, monitors and
structure, but so far haven't gotten anything to work. Is perhaps the
absorption too small for MEEP to handle (i.e. leading to significant
roundoff errors)? Is there a workaround? What are some typical values
to try if the defaults do not work?
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