To wit,
http://ab-initio.mit.edu/pipermail/meep-discuss/2007-February/000700.html:
Third, because the magnitude of k depends on the frequency, you can't
make a single source that produces light with a single angle (other
than normal incidence) over a broad bandwidth, as your control file
attempts to do. You need to use a narrow-bandwidth source, and do
multiple simulations if you want a transmission spectrum at a given
angle.
If you want to see the *field* pattern for a given angle, then you need a
narrowband (CW) source. But if you want the *flux* from a given angle,
then you can put in a broadband source and only take that frequency
component of the Fourier transform.
If you want the transmission *spectrum* at a single angle, then you need
multiple simulations. However, you can then get the transmission spectra
at multiple angles for free, as described below.
I'm sorry if my July post confused the issue.
I'd like to do what you describe; create a 2d dataset of scattering
properties over frequency and angle.
In that case, you can do it with a sequence of simulations as follows.
Let x be the direction parallel to your source plane, and y be the
direction perpendicular. Use Bloch periodic boundaries in the x direction
with k-point kx, and a source plane whose amplitude varies as exp(i 2 pi
kx x) in the x direction.
Do a sequence of simulations, for a sequence of kx values, where in each
simulation you get the flux as a function of frequency (w)
for a broadband source.
You now have a 2d dataset flux(kx, w). You now simply want to change
variables to flux as a function of theta and w, where theta=0 corresponds
to normal incidence (kx = 0). The change of variables is (assuming your
source is in vacuum so that |k| = w in Meep units):
theta = arcsin(kx / w)
Matlab or many other programs can plot this 2d dataset after your change
of variables, in any way that you want. If you want the transmission
spectra at fixed angles, you can simply interpolate the appropriate slice
of your data.
Steven
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