On Thu, 23 Sep 2010 18:38:22 -0700, Alex McLeod <[email protected]> wrote: > Hi Jack, > > In regards to your questions about near-field enhancement and > scattering, I have some comments to make.
(cut) > > Also, note that using flux regions will only let you compute > absorption, since fluxes won't let you spatially resolve the radiated > fields. The formula "E_scat=E_total-E_incident" is the conventional > way of "defining" the "scattered" part of the field distribution. > Since Maxwell's eqtns are linear, you know E_scat is induced only by > the charges in your geometry rather than by the source currents. But > to obtain this, you have to apply that formula using the spatially- > resolved field distributions in each of the incident faces to get > E_scat, etc. So, you need to output the in-plane fields in those > regions to HDF5 so you can load the data and do this calculation with > the spatially resolved fields. Then, calculate and integrate the > resulting Poynting vector fluxes. This is a NONTRIVIAL exercise, and > you will have to do some scripting to pull it off. I have written an > API to accomplish this, which I'll be publishing as part of an > interface to Meep at www.nanohub.org under the title "Molecular > Foundry Nanophotonics Toolkit" (crediting S. Johnson et al.), so keep > an eye out for that in the coming months. > Dear Alex and Meep users, I have just read today this mailing list message posted last September and I have a question. Isn't the procedure you describe accomplished by using the save-flux and load-minus-flux commands (for each of the surfaces of the box which includes the scattering object) in the libcl interface to Meep? Let me quote from the Meep tutorial webpage "Now, as described in the Meep introduction, computing reflection spectra is a bit tricky because we need to separate the incident and reflected fields. We do this in Meep by saving the Fourier-transformed fields from the normalization run (no-bend?=true), and loading them, negated, before the other runs. The latter subtracts the Fourier-transformed incident fields from the Fourier transforms of the scattered fields; logically, we might subtract these after the run, but it turns out to be more convenient to subtract the incident fields first and then accumulate the Fourier transform. All of this is accomplished with two commands, save-flux (after the normalization run) and load-minus-flux (before the other runs). " What is the difference with the procedure you describe? Thanks in advance for the answer, Giovanni -- ================================================ Giovanni Piredda Postdoc - AK Hartschuh Phone: ++49 - (0) 89/2180-77601 Fax.: ++49 – (0) 89/2180-77188 Room: E2.062 ---------------------------------------- Message sent by Cup Webmail (Roundcube) _______________________________________________ meep-discuss mailing list [email protected] http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss
