On Wed, 19 Apr 2006, JT wrote:
Do anyone know if it's feasible to calculate the dispersion, i.e.
propagation diagram (omega-beta), of fibres (in particular: multi-step,
graded-index, photonic crystal fibre, Omni guide fibre) with the
MPB-package? If yes, where I can get an appropriate ctl-file?
Did you have any luck with this? I also want to calculate the dispersion of
PCFs. Anyone have any suggestions?
Yes, we have done this many times. It's not particularly difficult in
general...it's just a 2d calculation where the dielectric function is
given by the fiber-cross section, and you set your k-point to be in the z
direction (out of the plane).
For index-guided fibers (e.g. solid-core PCFs, standard fibers, etcetera),
it is a very small and easy calculation because you are interested in the
lowest-lying bands, below the cladding light cone, so you only need to
calculate a few bands.
For hollow-core bandgap fibers the computation can be fairly large,
because it is a supercell calculation and for an NxN supercell you need to
compute O(N^2) bands before you get to the guided bands within the gap.
For OmniGuide and Bragg fibers it is much more efficient to use a
Bessel-function transfer-matrix method that exploits the cylindrical
symmetry, since you really only have to solve a 1d problem in that case.
Cordially,
Steven G. Johnson
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