On Thu, 16 Nov 2006, Sung Park LEE wrote:
After making the structure of PC slab with point defect cavity in the
center (only change the dielectric constant of the point defect cavity).
I want to study high-Q (long lifetime) resonant modes by using some MEEP
commands:
You don't say what type of defect structure you have or why your results
are "not correct", so it's hard to diagnose.
However, you have several problems I suspect.
First, your symmetries make no sense. You have three odd mirror symmetry
planes. At the very least, the z=0 mirror symmetry plane should be even,
corresponding to the "TE"-like modes of a slab of holes. Note that your
own source, which is Hz at z=0, has even symmetry with respect to z=0, so
you are violating your own symmetry.
Second, although you don't say what defect/cavity structure you are using,
there is a good chance that the mode is orthogonal to an Hz source at
(0,0,0). For example, if you decrease the radius of a hole to make a
defect in a triangular lattice of holes, then the first cavity mode that
it creates is a twofold-degenerate mode...these modes in the xy plane have
one even mirror symmetry plane and one odd plane, making them orthogonal
to an Hz source at (0,0,0), which is odd with respect to both x=0 and y=0.
If you don't know a priori what your mode will look like, you are better
off using no symmetry except for the z=0 mirror symmetry, and put your Hz
source at a random point in the xy plane, e.g. at (0.1234,0.4567,0). That
way you will be sure to excite all of the modes, unless you are extremely
unlucky.
Cordially,
Steven G. Johnson
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