On Tue, 6 Mar 2007, Young Soo Lee wrote:
I want to plot the band structure of 1D photonic crystals which is
excited by off-axis propagation. One example is shown by Fig.7 on Page
46 of Photonic Crystal: Molding the Flow of Light.
In my opinion, we should treat the multilayer film as a 2D photonic
crystal in this case. One possible code is as follows,
(set! geometry-lattice (make lattice (size 1 0.5 no-size))) ; 2d cell
No, the size should still be no-size in the y direction (parallel to the
mirrors). You can still put in a k vector in any direction you want.
By giving a finite periodicity (0.5) in the y direction, you will see a
"folded" band structure, that results from the periodic relabeling of k in
the finite Brillouin zone (as opposed to the infinite Brillouin zone for a
uniform direction, for which all k are distinct). This always results
when you have a supercell, and is a result of you posing the wrong
mathematical question, and is independent of the computational method.
(Besides the fact that you are wasting computational effort by specifying
more than no-size---along uniform directions, MPB only needs one pixel.)
Cordially,
Steven G. Johnson
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