On May 2, 2008, at 8:54 AM, andika asyuda wrote:
My problem is the result shows number larger then 1, at frequency near 0. And at other frequency, the number is too low. I do not see any peakse as the sign of existence of transmission band and band gap.
First of all, it is perfectly possible to get a transmission large than 1 in the experiment you are doing. The reason is that your source is quite close to the photonic crystal, meaning that it can be affected by the local density of states in the crystal and output either more power (e.g. near band edges where there is a high density of states) or less power (e.g. in a gap) than the same source surrounded by many wavelengths of vacuum. This seems to be a common confusion among users: in electromagnetism, the same current source can output different amounts of power depending on the surroundings.
Second, your .ctl file contains some errors. First, you specify a refractive index of 12.96, but I think you mean an epsilon of 12.96 --- this makes a big difference, because for such a huge index your structure is going to be very reflective at most wavelengths. Second, you have an Ez source (TM polarization), but you are passing Ey to stop-when-fields-decayed. Third, you said that for normalization you did (set! geometry ), but I think you meant (set! geometry '()) to set it to the empty list.
Note also that, assuming you really wanted epsilon of 12.96, for these parameters there should be a gap from a frequency of 0.2 to 0.25, so your frequency is too high.
The attached file works okay for me and shows the expected bandgap. Steven
slab2_s.ctl
Description: Binary data
_______________________________________________ meep-discuss mailing list [email protected] http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss
