mpb-discussDear Steven:
I am learning to use the programme , and I try an examples about photonic
crystal filled with liquid crystals in
the Reference( physical review B 67,073106 (2003)). But I find the result, the
dispersion relations of guided modes are so different compared with the results
in the Reference, which will be a error though their basic curves is similar.
This is 2D triangular lattice photonic crystal with air holes in GaAs
substrate. The backgound dielectric index is 11.4. We calculalte the dispersion
relations of line defect waveguides filled with liquid crystal, and the
attached file is about the supercell, and Dark and light shaded regions
indicate GaAs and liquid crystals, respectively. When the rotation angle of the
director of the liquid crystal is 90°, the components of the dielectric tensor
are ne*ne,no*no,and zero in xx ,yy, and xy directions,respectively, where ne is
1.706 ,and no is 1.522 ( this direction is in accord with that in the
supercell). I try some examples about liquid crystals, and the problem is also
present. Would you mind scanning my ctl file?
(define-param supercell-y 10) ; the (odd) number of lateral supercell periods
(set! geometry-lattice (make lattice
(basis1 (/ (sqrt 3) 2) 0.5)
(basis2 (/ (sqrt 3) 2) -0.5)
(size 1 supercell-y no-size)))
(define-param eps 11.4) ; the dielectric constant of the bandground
(define-param r 0.45) ; the hole radius in the bulk crystal
(set! default-material (make dielectric (epsilon eps)))
(set! geometry (list (make cylinder
(center 0 0 0) (radius r) (height infinity)
(material air))))
(set! geometry
(append
; duplicate the bulk crystal holes over the supercell:
(geometric-objects-lattice-duplicates geometry)
; add a rod of dielectric, to erase a row of holes and form a waveguide:
(list
(make cylinder (center 0 0 0) (radius r) (height infinity)
(material (make dielectric (epsilon eps)))))
(list
(make cylinder (center 0 0 0) (radius r) (height infinity)
(material (make dielectric-anisotropic (epsilon-diag 2.910436
2.316484 2.316484)))))))
(define Gamma (vector3 0 0 0))
(define K' (lattice->reciprocal (vector3 0.5 0 0))) ; edge of Brillouin zone.
(set! k-points (interpolate 100 (list Gamma K')))
; the bigger the supercell, the more bands you need to compute to get
; to the defect modes (the lowest band is "folded" supercell-y times):
(define-param extra-bands 6) ; number of extra bands to compute above the gap
(set! num-bands (+ supercell-y extra-bands))
(set-param! resolution 32)
(run-te
(output-at-kpoint (list-ref k-points (quotient(length k-points) 4))
fix-hfield-phase output-hfield-z))
Thank you a lot. Look forward to your reply!
Best regards
Hongliang Ren
hlren
[EMAIL PROTECTED]
2006-08-20
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