Sanchit, The problem is that your incident flux is being bombarded by reflections coming from the structure.
The proper way to normalize is to run the simulation twice, once without the structure in question, and once with the structure in question. Since in this case the entire waveguide is what you want the transmission of, the runs would be: 1. No structure at all. 2. Waveguide structure. Then it's just ouput/input like you said. Hope that helps! Matt On Wed, Jul 7, 2010 at 12:21 AM, Sanchit Khatavkar <[email protected]>wrote: > Dear Dr.Steven and meep users, > > > I am trying to find the transmission spectrum of a straight waveguide using > a gaussian source. > I am getting negative values for some frequencies > > and for some, the transmission shoots up, way more than 1. > > The intensity is very less too. > > > > frequency > incident flux > transmitted flux > fux2: 0.610151515151515 -9.70715540181083e-5 3.61878776165123e-6 flux2: > 0.611161616161616 -1.3586153173961e-4 3.18042124444992e-6 flux2: > 0.612171717171717 -2.08814643514626e-4 -1.8376793917394e-7 > > > From what I could gather by reading the archives, this behavior might be > due to improper normalization. > > My structure is a straight waveguide. The way I am normalizing is by > defining two flux regions , one at the input, just after the source and > another at the end of the waveguide. > > > ------------------------------------------------------- > Source input flux > output flux > > ------------------------------------------------------ > > transmission = output flux/input flux > > Normally, if we have structure with say cavities, then to normalise, we run > meep without the cavities to find the incident flux. > > In my structure, since it is just a straight waveguide, what would be the > proper way of normalization? > > Is there any other reason for such a behavior? > > > I am attaching the ctl file for reference. > > > Thanks a lot, > Sanchit > > > _______________________________________________ > meep-discuss mailing list > [email protected] > http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss >
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