Hi, everyone:
I have one question about PML. I ran one case
with 2-D waveguide structure consisting of three
layers. I know the correct description for PML
is just to set the thickness of PML and meep will
automatically put it inside the computation cell.
However, the result was not expected. The light just
disappeared after short distance even I set long
waveguide length.
However, if I add the thickness of PML in
cell size, the result showed light would propagate for
long distance.
I am wondering if PML will produce so huge
difference that it affects the capability of
waveguide. And whether the second result is wrong? It
can propagate because of wrong PML position?
The ctl file is below.
Thank you in advance
Adrian
The ctl file is below:
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
(define-param unit 1e-8) ;
(define lam 620e-9) ;
(define lamu (/ lam unit)) ;
(define fcen (/ unit lam)) ;
(define dpml 3) ;
(define gamma_ag 1.406e+14)
(define c 3e+8)
(define gama (/ (* unit gamma_ag) c 2 pi))
(define rlamda_ag 137.6e-9)
(define wp (/ unit rlamda_ag))
;
source center frequency
(define e_ag_inf 5.4264)
(define-param wx 600 ) ; width in x
(define-param wy 2) ; width in y
(define-param pady 25 ) ; pad in y
(define-param sx (+ wx dpml dpml))
(define-param sy (+ wy pady pady dpml dpml))
; the two lines above are not like example but allowed
;light propagate for a long distance.
; If I dropped off dpml from parethesis, light just
;propagated for a short distance
(set! eps-averaging? false)
(set! geometry-lattice (make lattice (size sx sy
no-size)))
(define Ag
(make dielectric (epsilon e_ag_inf)
(polarizations
(make polarizability
(omega 1e-20) (gamma gama)
(delta-epsilon (* wp wp 1e+20 1e+20)))
)))
(define clad (make dielectric (epsilon 2.89)))
(define core (make dielectric (epsilon 6)))
(set! geometry
(list
(make block (material clad) (center 0 (/ (+
pady wy) 2)) (size wx pady infinity))
(make block (material Ag) (center 0 0)
(size wx wy infinity))
(make block (material clad) (center 0 (/ (+
pady wy) -2)) (size wx pady infinity))
))
(set! sources (list
(make source
(src (make continuous-src
(frequency
fcen))) (component Hz) (center (+ (/ sx -2) 2) 0
)
(size (* 1.2 wy) 0 ))))
(set! pml-layers (list (make pml (thickness
dpml))))
(set! resolution 10)
(run-until 1500
(at-beginning output-epsilon)
(at-end output-hfield-z
output-efield-x
output-efield-y output-sfield-y output-sfield-x))
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