On Mar 12, 2009, at 11:55 AM, adrian wrote:
I use symmetry so often and it is very efficiency.
But I wonder when we use symmetry, does it disregard some
resonant modes? Since even mode and odd mode have the different
pattern. If the mirror plane is put in the nodal of odd mode, then I
may only excite odd modes. Of course, this assumption is based on
the symmetry in meep is carried out by using PEC or PMC, which is
the same as in FEM calculation.
However, I looked at the meep reference, it says:" Meep exploits
it as an internal optimization, while everything else about the
simulation appears the same as if you didn't specify the symmetry."
It sounds like symmetry in meep should not disregard other modes.
If it is true, can I know how meep does symmetry?
For example, if you use an odd-symmetry source, the even-symmetry
modes cannot be excited. If you then specify odd symmetry in Meep,
nothing changes. The even symmetry modes are not "disregarded", they
are simply not relevant. Vice-versa for an even-symmetry source
I should make one caveat: the above is for linear simulations. In a
chi2 nonlinear system, it is possible for an odd-symmetry source to
excite an even-symmetry mode (because the square of an odd function is
an even function). In this case, imposing odd symmetry in Meep will
affect the results of the simulations.
Steven
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