It's certainly possible to make a unidirectional source in MPB, using
a combination of electric and magnetic currents. (This is what the
"total-field/scattered-field" approach does.) However, if you want it
to be unidirectional to high precision, you have to very carefully
account for discretization effects and numerical dispersion when
setting up your mode amplitudes, and this gets complicated very
quickly for things like gaussian pulses (as opposed to single-
frequency planewaves).
However, from my perspective I've never seen much reason to do this.
The usual motivation to try to get a unidirectional sources is to
separate the incident field from the scattered field (because the
field behind a unidirectional source is only the scattered field, that
makes it easy). However, to me it is much easier just to do two
simulations, using Meep's feature to subtract the Fourier transforms
as explained in the Meep tutorial, than to implement a high-precision
wide-bandwidth unidirectional source.
On Jul 13, 2012, at 11:42 AM, Eric CASSAN wrote:
I would have a very similar question as the one raised by Puck. It
seems that nobody has replied to him.
Would you know a way to do this?
Thank you.
With best regards,
Eric
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
=
======================================================================
From: Puck Ja <puckja@...>
Subject: Unidirectional Gaussian beam
Newsgroups: gmane.comp.science.electromagnetism.meep.general
Date: 2008-02-11 15:15:03 GMT (4 years, 21 weeks, 6 days and 25
minutes ago)
Hi,
I have followed some discussions and tried to make Gaussian beam
with success. However, the beam is bi-directional, which means that
it will propagate away from the source plane toward both normal
directions (or with some "tilting" angle). There are some
unidirectional source for FDTD (the beam only propagate in one side
of source plane). I wonder if anybody has done that or if it is
possible with MEEP.
Thanks!
Puck
_______
_______________________________________________
meep-discuss mailing list
meep-discuss@ab-initio.mit.edu
http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss
