Hi all,
I recently tried the coordinate transformation trick to try to fit more grid
points in small features of my structures, and the resulting transmission seems
to have reflections and pre-pulses that did not appear in the untransformed
simulations. I did adjust the courant factor for to accommodate the smaller
indexes of refraction. My code is below if you have any suggestions on what I
should change.
(reset-meep)
(define Cu (make medium (epsilon-diag (vector3 -676.8 -676.8 -270720)) (mu-diag
(vector3 0.05 0.05 20))(D-conductivity-diag (vector3 201.0995 201.0995
80439.8))))
(define-param lattice-size 80) ; size of x - y square of computational space
(define-param lattice-length 25000) ; length of computational space
(define-param pml-thickness 1600) ; thickness of pml layer
(define-param substrate-index 3.42) ; refractive index of substrate
(define-param fcen 0.00833) ; center wavelength of incident pulse
(define-param df 0.01666) ; parameter related to the spectral width of the pulse
(define-param t 4) ; metal depth (z dir)
(define Ar (make medium (epsilon-diag (vector3 0.05 0.05 20)) (mu-diag (vector3
0.05 0.05 20))))
(define Si (make medium (epsilon-diag (vector3 0.58482 0.58482 233.928))
(mu-diag (vector3 0.05 0.05 20))))
(define-param l 60) ; side-length
(define-param w 5) ; microsrtip width
(define-param d 0.3) ; dielectric thickness
(set! resolution 0.5)
(set! Courant 0.02886)
(set! eps-averaging? false)
(set! geometry-lattice (make lattice (size lattice-size lattice-size
lattice-length)))
(set! geometry
(list
(make block
(center 0 0 0)
(size infinity infinity infinity)
(material Ar)
)
(make block
(center 0 0 (* lattice-length .75))
(size lattice-size lattice-size (/ lattice-length 2))
(material Si)
)
(make block
(center 0 0 0)
(size lattice-size lattice-size t)
(material Ar)
)
(make block
(center 0 0 0)
(size w l t)
(material Cu)
)
(make block
(center 0 0 0)
(size l w t)
(material Cu)
)
(make block
(center (/ l 4) (/ (- l w) 2) 0)
(size (/ l 2) w t)
(material Cu)
)
(make block
(center (/ (- l w) 2) (/ l -4) 0)
(size w (/ l 2) t)
(material Cu)
)
(make block
(center (/ l -4) (/ (- w l) 2) 0)
(size (/ l 2) w t)
(material Cu)
)
(make block
(center (/ (- w l) 2) (/ l 4) 0)
(size w (/ l 2) t)
(material Cu)
)
)
)
(set! k-point (vector3 0 0 0)); enable periodic boundary condition
(set! pml-layers (list (make pml (thickness 1600) (direction Z)))); set pml
(set! sources (list
(make source
(src(make gaussian-src (frequency fcen) (fwidth df)))
(component Ex)
(center 0 0 (- (- (/ lattice-length 2) pml-thickness .5)))
(size lattice-size lattice-size 0)
)
)
)
;(run-sources+ (stop-when-fields-decayed 10 Ey (vector3 0 0 -2) 1e-4)
(run-until 8000
(to-appended "trangc1layer"
(in-volume (volume (center 0 0 (- (/ lattice-length 2) pml-thickness
.5)) (size 0 0 0)) output-efield-x))
(at-beginning output-epsilon))
(reset-meep)
(define Cu (make medium (epsilon -1439.8) (D-conductivity (/ (* 2 pi 0.15
1066.7) 1))))
(define-param lattice-size 80) ; size of x - y square of computational space
(define-param lattice-length 25000) ; length of computational space
(define-param pml-thickness 1600) ; thickness of pml layer
(define-param substrate-index 3.42) ; refractive index of substrate
(define-param fcen 0.00833) ; center wavelength of incident pulse
(define-param df 0.01666) ; parameter related to the spectral width of the pulse
(define-param t 4) ; metal depth (z dir)
(define-param l 60) ; side-length
(define-param w 5) ; microsrtip width
(define-param g 0.05) ; gap-length
(define-param Ar (make medium (epsilon-diag (vector3 0.05 0.05 20)) (mu-diag
(vector3 0.05 0.05 20))))
(define-param Si (make medium (epsilon-diag (vector3 0.58482 0.58482 233.928))
(mu-diag (vector3 0.05 0.05 20))))
(set! resolution 0.2)
(set! Courant 0.02886)
(set! eps-averaging? false)
(set! geometry-lattice (make lattice (size lattice-size lattice-size
lattice-length)))
(set! geometry
(list
(make block
(center 0 0 0)
(size lattice-size lattice-size lattice-length)
(material Ar)
)
(make block
(center 0 0 (* lattice-length .75)) (size lattice-size lattice-size
(/ lattice-length 2))
(material Si)
)
(make block
(center 0 0 0)
(size lattice-size lattice-size t)
(material Ar)
)
)
)
(set! k-point (vector3 0 0 0)); enable periodic boundary condition
(set! pml-layers (list (make pml (thickness 1600) (direction Z)))); set pml
(set! sources (list
(make source
(src(make gaussian-src (frequency fcen) (fwidth df)))
(component Ex)
(center 0 0 (- (- (/ lattice-length 2) pml-thickness .5)))
(size lattice-size lattice-size 0)
)
)
)
;(run-sources+ (stop-when-fields-decayed 10 Ey (vector3 0 0 -2) 1e-4)
(run-until 8000
(at-beginning output-epsilon)
(to-appended "refgc1layer"
(in-volume (volume (center 0 0 (- (/ lattice-length 2) pml-thickness
.5)) (size 0 0 0)) output-efield-x))
)
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