2012/10/16, Filip Dominec <filip.domi...@gmail.com>: > Hi, David, > I guess that the simulation you are performing probably uses > Bloch-periodic boundaries on both xy and zy faces. This simulates a > 2-dimensional, strictly periodic array of scattering spheres. Although > it is unrealistic, it should provide a reasonable transmission > spectrum for the directly passing wave. So I think you may get good > results with the x-z monitor planes approach. > > Note that there is some reflection from the sphere, that is registered > by the first monitor plane, too. So the monitor plane before the > sphere does not provide the information about the input spectrum. You > may use a slow method of first sending a pulse into empty volume, and > then to rerun it with the metallic sphere. However, there is a simple > trick to separate forward and backward propagating waves (forward is > (E+H/z0)/2 whereas backward is (E-H/z0)/2). See > http://fzu.cz/~dominecf/misc/meep/sphere.py for example. > > Your array behaves as a diffraction grating for higher modes. Using > their orthogonality, you might separate them from each other and look > at their spectra, but as I wrote this is unrealistic as you have the > spheres randomly dissolved. > > Filip > > 2012/10/12, Filip Dominec <filip.domi...@gmail.com>: >> Hi, I will answer in Wednesday. >> Regards >> F. >> >> On Thu, 11 Oct 2012 14:35:03 -0700 (PDT) >> david anderson <david.anderson1...@yahoo.com> wrote: >> >>> Dear Filip, >>> >>> >>> Thanks again. Transmission calculated for one plane is correct inn this >>> case? For example propagation direction for my simulation is y-axis so >>> if >>> I calculate transmission from a x-z plane after the sphere can I get the >>> result of paper or it is required to calculate the transmission from >>> sphere in all directions? >>> >>> >>> Best regards, >>> >>> David >>> >>> >>> >>> ________________________________ >>> From: Filip Dominec <filip.domi...@gmail.com> >>> To: david anderson <david.anderson1...@yahoo.com> >>> Sent: Thursday, October 11, 2012 2:03 PM >>> Subject: Re: [Meep-discuss] extinction spectra >>> >>> Hi, I have simulated something similar few weeks ago, observing >>> localized plasmons. If you were interested in my python-meep script, I >>> can send it to you in the next week. >>> The term 'extinction' may be somewhat vague; first I would recommend >>> you to calculate the intensity transmission and then I would compare >>> the extinction obtained by -log(T) to that provided in the article. >>> This is surely something coming from the chemistry (of silver >>> nanoparticles) and it probably takes into account the concentration in >>> some way. >>> Best regards, >>> Filip >>> >>> 2012/10/11, david anderson <david.anderson1...@yahoo.com>: >>> > >>> > >>> > Dear Filip, >>> > >>> > >>> > Thanks for your answer. Actually I want to simulate a silver nano >>> > sphere >>> > and >>> > for testing correctness of my simulation results I want to check them >>> > with >>> > some papers but in the papers the results are named extinction spectra >>> > and I >>> > couldn't find definition of it. In my simulation I illuminate an >>> > sphere >>> > by a >>> > Guassian plane wave and then I don't know what must be computed to >>> > show >>> > extinction spectra. >>> > >>> > Bests, >>> > David >>> > >>> > >>> > ________________________________ >>> > From: Filip Dominec <filip.domi...@gmail.com> >>> > To: david anderson <david.anderson1...@yahoo.com> >>> > Cc: "meep-discuss@ab-initio.mit.edu" <meep-discuss@ab-initio.mit.edu> >>> > Sent: Thursday, October 11, 2012 12:52 PM >>> > Subject: Re: [Meep-discuss] extinction spectra >>> > >>> > Dear David, >>> > I have read your question also the first time you formulated it, but >>> > did not feel experienced enough to give a really good answer. >>> > >>> > However, as far as I can remember, the exctinction should be defined >>> > as -log(T), where T is intensity transmission. Both are usually a >>> > function of frequency (hence ext. spectrum). Hope this helps. Maybe >>> > you should point me to some MEEP example that uses it. I personally >>> > mostly use the amplitude transmission (t) and I consider the >>> > extinction to be something from analytical chemistry. >>> > Filip >>> > >>> > 2012/10/11, david anderson <david.anderson1...@yahoo.com>: >>> >> Dear MEEP users, >>> >> >>> >> >>> >> I have a question about extinction spectra. what is the definition of >>> >> extinction spectra and how can I compute it using fdtd or meep? >>> >> >>> >> Thanks in advance, >>> >> David Anderson >> >
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