Good night meep user
I encountered a problem about meep simulation about periodic dielectric,
sequence of hole at a block of silicon. I calculate flux at 3 points, the left
edge (near the source) , center, and right edge. I calcuate transmission by
divide the value of flux at center and left edge with the right edgeI got the
surprising result because I saw there some frequencies with transmission value
larger than 1. I hope some one can tell me what my mistake is
Thank you so much for the help. I provide my code as following
; Some parameters to describe the geometry:
(define-param eps 11.9) ; dielectric constant of waveguide
(define-param w 1.43) ; width of waveguide
(define-param r 0.26) ; radius of holes
(define-param d 1.4) ; defect spacing (ordinary spacing = 1)
(define-param N 5) ; number of holes on periodic mirror
(define-param Ni 4) ; number of holes on inside cavity
(define-param No 3) ; number of holes on outside defect
; The cell dimensions
(define-param sy 6) ; size of cell in y direction (perpendicular to wvg.)
(define-param pad 2) ; padding between last hole and PML edge
(define-param dpml 1) ; PML thickness
(define sx (+ (* 2 (+ pad dpml N Ni No)) d -1)) ; size of cell in x direction
(set! geometry-lattice (make lattice (size sx sy no-size)))
(set! geometry
(append ; combine lists of objects:
(list (make block (center 0 0) (size infinity w infinity)
(material (make dielectric (epsilon eps)))))
(geometric-object-duplicates (vector3 1 0) 0 (- N 1)
(make cylinder (center (+ (/ d 2) Ni) 0) (radius r) (height infinity)
(material air)))
(geometric-object-duplicates (vector3 -1 0) 0 (- N 1)
(make cylinder (center (- (/ d -2) Ni) 0) (radius r) (height infinity)
(material air)))
(geometric-object-duplicates (vector3 1 0) 0 (- Ni 1)
(make cylinder (center (/ d 2) 0) (radius r) (height infinity)
(material air)))
(geometric-object-duplicates (vector3 -1 0) 0 (- Ni 1)
(make cylinder (center (/ d -2) 0) (radius r) (height infinity)
(material air)))
(geometric-object-duplicates (vector3 1 0) 0 (- No 1)
(make cylinder (center (+ (/ d 2) Ni N) 0) (radius r) (height
infinity)
(material air)))
(geometric-object-duplicates (vector3 -1 0) 0 (- No 1)
(make cylinder (center (- (/ d -2) Ni N) 0) (radius r) (height
infinity)
(material air)))))
(set! pml-layers (list (make pml (thickness dpml))))
(set-param! resolution 20)
(define-param fcen 0.25) ; pulse center frequency
(define-param df 0.2) ; pulse width (in frequency)
(define-param nfreq 500) ; number of frequencies at which to compute flux
(set! sources (list
(make source
(src (make gaussian-src (frequency fcen) (fwidth df)))
(component Ey)
(center (+ (/ d 2) Ni N No r 1) 0)
(size 0 w))))
(set! symmetries (list (make mirror-sym (direction Y) (phase -1))))
(define trans ; transmitted flux
(add-flux fcen df nfreq
(make flux-region
(center (+ (/ d 2) Ni N No r) 0) (size 0 (* w 2)))))
(define trans2 ; transmitted flux
(add-flux fcen df nfreq
(make flux-region
(center 0 0) (size 0 (* w 2)))))
(define trans3 ; transmitted flux
(add-flux fcen df nfreq
(make flux-region
(center (* (+ (/ d 2) Ni N No r) -1) 0) (size 0 (* w 2)))))
(run-sources+ (stop-when-fields-decayed
50 Ey
(vector3 (* (+ (/ d 2) Ni N No r) -1) 0)
1e-3)
(at-beginning output-epsilon)
(during-sources
(to-appended "hz" (at-every 0.4 output-hfield-z))))
(display-fluxes trans trans2 trans3) ; print out the flux spectrum
with regard
Andika Asyuda
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