Dear Steven and MPB's users,
I would like to calculate the waveguide dispersion of triangular PCs slab.
The waveguide width is not equal to conventional width of W1 waveguide, and is
formed by moving (up and down) the nearest neighbor air holes around the linear
defect (For example, W=0.65*sqrt3 =0.65*W1). The same question was already
asked by Nils Jensen on 21 Apr 2008 in the mpb-discussion, his mail titled
"Waveguide in 2D-PCs of triangular symmetry". But I did not find the solution.
I would like to define the structure like the usual W1 waveguide, but
with different waveguide width. But when I used the similar codes like Nils
Jensen used, the same problem appeared. The two nearest neighbor holes are not
symmetry by y axis, as the attached picture showed.
I tried several other ways to define the structure, but the problem
remains. Below is one of the codes, and the attached picture is the unexpected
structure of the result. Other ways have the same result of structure output in
the *.out file.
Is there someone know how to define the structure correctly?
Thanks!
(define-param h 0.6) ; the thickness of the slab
(define-param eps 12) ;
(define-param subeps 2.1025) ;
(define-param r 0.3335 ) ; the radius of the holes
(define-param supercell-h 4) ; height of the supercell
(define-param supercell-y 10.3) ; the (odd) number of lateral supercell periods
(set! geometry-lattice (make lattice (size 1 supercell-y supercell-h)
(basis1 (/ (sqrt 3) 2) 0.5)
(basis2 (/ (sqrt 3) 2) -0.5)))
(set! geometry
(list (make block (material (make dielectric (epsilon subeps)))
(center 0 0 (* 0.25 supercell-h)) (size infinity infinity (*
0.5 supercell-h)))
(make block (material (make dielectric (epsilon eps)))
(center 0) (size infinity infinity h))))
(set! geometry
(append geometry
(list (make cylinder (material air)
(center 0 0.65 0) (radius r) (height h))
(make cylinder (material air)
(center 0 1.65 0) (radius r) (height h))
(make cylinder (material air)
(center 0 2.65 0) (radius r) (height h))
(make cylinder (material air)
(center 0 3.65 0) (radius r) (height h))
(make cylinder (material air)
(center 0 4.65 0) (radius r) (height h))
(make cylinder (material air)
(center 0 -0.65 0) (radius r) (height h))
(make cylinder (material air)
(center 0 -1.65 0) (radius r) (height h))
(make cylinder (material air)
(center 0 -2.65 0) (radius r) (height h))
(make cylinder (material air)
(center 0 -3.65 0) (radius r) (height h))
(make cylinder (material air)
(center 0 -4.65 0) (radius r) (height h))
)))
;define the defect of the clad layer(fill in)
; 1st Brillouin zone of a triangular lattice:
(define Gamma (vector3 0 0 0))
(define K' (lattice->reciprocal (vector3 0.5 0 0))) ; edge of Brillouin zone.
(define-param k-interp 8) ; the number of k points to interpolate
(set! k-points (interpolate k-interp (list Gamma K')))
(set-param! resolution (vector3 24 24 24))
(set-param! mesh-size 7)
(set-param! num-bands 15)
; Run even and odd bands, outputting fields only at the K point:
(run-zeven)
Best wishes,
Yours,
Jin Hou
Wuhan National Laboratory for Optoelectronics,
College of Optoelectronic Science and Engineering,
Huazhong University of Science & Technology,
Wuhan, 430074, P.R.CHINA
Phone: 86-027-87792195
Web: http://oe.hust.edu.cn/sub_web/zzp/lab_web/Index.html
开心过好每一天！
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