Hi, I use meep to obtain band structure of W1 waveguide.( )It is a triangular lattice of air holes in dielectric materials. The band structure is shown below:
Question:
1, First of all, the position of transmission line in the forbiden band is not
right.
2, Second of all, there should be a lot a resonant dot below frequency range
0.20. but in the Fig there are only a few dot.
below is the ctl file
===================
; Some parameters to describe the geometry:
(define-param eps 11.56); dielectric constant of waveguide
(define-param w 1.2); width of waveguide
(define-param r 0.36); radius of holes
; The cell dimensions
(define-param sy 16); size of cell in y direction (perpendicular to wvg.)
(define-param dpml 1); PML thickness (y direction only!)
(set! geometry-lattice (make lattice (size 1 sy no-size)))
(set! geometry (append
(list
(make block (center 0 0) (size infinity infinity infinity)
(material (make dielectric (epsilon eps))))
)
(geometric-objects-duplicates (vector3 0 -1.732) 0 2
(list
(make cylinder (center 0.5 -0.866)
(radius r)
(height infinity)
(material air)
)
(make cylinder (center -0.5 -0.866)
(radius r)
(height infinity)
(material air)
)
;;;;
;; middle holes
(make cylinder (center 0 -1.732)
(radius r)
(height infinity)
(material air)
)
)
)
(geometric-objects-duplicates (vector3 0 1.732) 0 2
(list
(make cylinder (center 0.5 0.866)
(radius r)
(height infinity)
(material air)
)
(make cylinder (center -0.5 0.866)
(radius r)
(height infinity)
(material air)
)
;;;;
;; middle holes
(make cylinder (center 0 1.732)
(radius r)
(height infinity)
(material air)
)
)
)
))
(set-param! resolution 16)
(set! pml-layers (list (make pml (direction Y) (thickness dpml))))
(define-param fcen 0.10); pulse center frequency
(define-param df 1.5); pulse freq. width: large df = short impulse
(set! sources (list
(make source
(src (make gaussian-src (frequency fcen) (fwidth df)))
(component Hz) (center 0.1234 0.221))))
;(set! symmetries (list (make mirror-sym (direction Y) (phase -1))))
;(set-param! k-point (vector3 0.4 0))
;(run-sources+ 300 (after-sources (harminv Hz (vector3 0.1234) fcen df)))
(define-param k-interp 19)
(run-k-points 300 (interpolate k-interp (list (vector3 0) (vector3 0.5))))
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<<inline: 截图1.jpg>>
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