The Meep reflection spectrum is Fourier transforming the fields using exactly the formula given in the Meep Introduction (see the section "transmission/reflection spectra"). No tricks. Maybe try evaluating this formula "manually" in Matlab in case you aren't using the fft() function correctly?
On Feb 6, 2009, at 4:11 PM, matt wrote: > > > > No no, it's not that simple. it's much smaller than 2pi. have a > look at this image: > > http://www.mail-archive.com/meep-discuss@ab-initio.mit.edu/msg02384/e2.png > > The inverted-peak in the spectrum is at 300 THz (blue curve), but > the fft shows it at about 330 THz (black curve). > > The excitation is a gaussian with start frequency 195 THZ and stop > frequency 330THz. > > > > > > On Fri, 6 Feb 2009, Steven G. Johnson wrote: > >> >> On Feb 6, 2009, at 6:55 AM, matt wrote: >>> In meep, if you generate a broadband pulse, an fft of the field >>> data will show that the pulse is at a higher frequency than what >>> you defined in the source. >> >> That just means you are interpreting the frequency units wrong >> (either in Meep or in the FFT). Possibly you are forgetting about >> a factor of 2pi? _______________________________________________ meep-discuss mailing list meep-discuss@ab-initio.mit.edu http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss
