On May 29, 2009, at 11:55 AM, matt wrote:
I was wondering how well eps-averaging works when the materials are
defined as lossy.
I guess that meep is basing it's averaging on eps_inf and not on the
full complex permittivities. Is that correct? If so, what does it
mean to have eps-averaging enabled with lossy materials present?
Correct, Meep currently only does subpixel averaging of the
nondispersive part of epsilon (and mu).
The dispersive part is not averaged at all. This means that any sharp
interfaces between dispersive materials will dominate the error, and
you will probably get only first-order convergence, the same as if you
do no no subpixel averaging at all.
It's possible that the subpixel averaging may still improve the
constant factor in the convergence if not the asymptotic convergence
rate, if you also have a lot of interfaces between nondispersive
materials or if the dispersion is small (i.e. if epsilon is close to
\epsilon_\infty over your bandwidth). On the other hand, if the
dispersion is large and most of your interfaces are between large-
dispersion materials, then subpixel averaging may not help at all and
you might as well turn it off.
The subpixel averaging shouldn't hurt you, though, except possibly in
performance.
Steven
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