On Jul 27, 2009, at 7:18 AM, Yinlan Ruan wrote:
I am trying to study field ehancement in a 40nm hole at a nanowire
fiber core
with its diameter around 450 nm, and the enhanced field's near field
transmission in the free space after outputing from the fiber. From
comsol, as
shown in the attachment,I got two eigen modes. One has enhancement
in the hole,
which is in agreement with theory, another one just has enhancement
at the
interface,and the field in the center of the hole are very small.
However the mode I got from Meep, the field in the centre of the
hole always
very low compared to that in the interface. I like to get the same
correct
result to that from COMSOL with strong field enhancement in the
hole. Could you
please help me to have a look at my code?Thanks.
I haven't looked in detail at your simulation, but one thing is
glaring. You say that you are computing "eigenmodes" in Comsol. You
are not computing eigenmodes in Meep, you are computing the response
to either a CW source or a gaussian pulse with a fairly broad bandwidth.
To see an eigenmode in a time-domain program like Meep, you want to go
through a two-step process:
1) Hit it with a broad-bandwidth pulse, and use harminv to find the
resonant modes.
2) For each resonant mode, do another simulation with a narrow-
bandwidth pulse centered at the resonant frequency. Wait until the
source has turned off, and then look at the fields, which should be
your resonant mode (if you used a narrow enough bandwidth to avoid
exciting other modes).
See, for example, how the Meep tutorial analyzes a ring resonator.
Steven
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