Cecil,
To compute near-field enhancement, just output field values Ex, Ey,
and Ez in the region of interest of your simulation using a 2- or 3-D
volume. Enhancement is given by |E|^2=|Ex|^2+|Ey|^2+|Ez|^2. It would
also be wise to follow the identical procedure in the absence of your
structure (a "normalization" run) to obtain an |E|^2 value for your
incident field value. Divide the first by the second and you have
normalized near-field enhancement. It's ideal to Fourier transform
your data sets and place them in the frequency domain first so you can
obtain enhancement as a function of frequency. Note however that
you'll need to use illumination with a Gaussian pulse source spanning
your bandwidth of interest.
To calculate the scattering cross section is a little more involved.
Define 2-D volume surfaces that surround your structure in a cubic
fashion, and output the in-plane E and B-field components for each of
these volumes. Do the same with a "normalization" run. Obtain
"scattered field" values as E_scat=E_total-E_norm for each field
component. With the scattered field values, compute the integrated
outbound flux from each 2-D surface volume with the formula for the
Poynting vector. Again, you should Fourier transform your scattered
field data sets first if you're interested in a frequency-dependent
scattering cross section. Add your total outbound fluxes together,
and finally divide by the per-pixel incident flux. Calculate the
incident flux with the "normalization" data sets over whichever 2-D
volumes you consider to be facing your illuminating source. I've
obtained scattering efficiencies in agreement with the literature
following these prescriptions using Meep.
Remember that the "normalization" run is crucial for definition of
your "incident" field as well as for computing the scattered fields.
And lastly, be sure to employ a model for the frequency-dependent
dielectric function of your metallic sphere which is accurate in your
bandwidth of interest. There are several such published material
models.
Best of luck,
Alex
____________________________________________________________________
Alexander S. McLeod
B.A. Physics and Astrophysics - University of California at Berkeley
Simulation Engineer - Theory Group, Molecular Foundry (LBNL)
Site Lead - Network for Computational Nanotechnology at Berkeley / MIT
[email protected] 707-853-0716
____________________________________________________________________
On Jul 17, 2010, at 9:00 AM, [email protected]
wrote:
Send meep-discuss mailing list submissions to
[email protected]
To subscribe or unsubscribe via the World Wide Web, visit
http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss
or, via email, send a message with subject or body 'help' to
[email protected]
You can reach the person managing the list at
[email protected]
When replying, please edit your Subject line so it is more specific
than "Re: Contents of meep-discuss digest..."
Today's Topics:
1. FW: Information Required (cecil chalmers)
From: cecil chalmers <[email protected]>
Date: July 17, 2010 4:48:17 AM PDT
To: <[email protected]>
Subject: [Meep-discuss] FW: Information Required
Dear meep users,
I think nobody read my 1st email, thats why i am
sending you again. Please somebody tell me how to calculate the Near
Field Enhancement and Scattering cross section of metallic
nanosphere in meep?
Best Regards,
C.C
From: [email protected]
To: [email protected]
Subject: Information Required
Date: Wed, 14 Jul 2010 12:35:24 +0200
Dear MEEP Users,
Does anybody know how to calculate the Near field Enhancement
and Scattering Cross Section of metallic nanoparticles in MEEP?
Thanks.
Hotmail: Powerful Free email with security by Microsoft. Get it now.
Your E-mail and More On-the-Go. Get Windows Live Hotmail Free. Sign
up now.
_______________________________________________
meep-discuss mailing list
[email protected]
http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss
_______________________________________________
meep-discuss mailing list
[email protected]
http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss
