Dear Professor Steven and MEEP users,
I found another problem when using meep 0.20.3. It is said in meep's
tutorial that the PML is inside the computational cell. Does it mean that the
original structures still remain in the PML zones. In my simulation of metallic
waveguide, I found the PML lost its effectiveness and some new strange modes
are excited in PML zones after some steps. The amplitude of the fields in PML
come to 10^96 at last. I think there must be something wrong, the PML should be
a absorbing material.
This time I use meep 0.20.3 compiled from source.
My ctl scripts:
(define a 100e-9) ; define the unit, 100 nm
(define sx 20) ; size of x, 4 um
(define sy 5) ; size of y
(define dpml 4)
(use-output-directory)
(set! geometry-lattice
(make lattice (size sx sy no-size)))
; ------------------------------------
; define material silver
(define cc (/ (* 2 (* pi 3e+8)) a)) ; unit of frequency in meep
(define wp_ag (/ 1.3798e16 cc))
(define gamma_ag (/ 2.72293e13 cc))
(define Ag
(make dielectric (epsilon 3.7)
(polarizations (make polarizability
(omega 1e-20)
(gamma gamma_ag)
(delta-epsilon (* wp_ag wp_ag 1e40))))))
(define wid 1)
(set! default-material Ag)
(set! geometry
(list
(make block
(center 0 0)
(size sx wid infinity)
(material air))))
; set source
(set! sources (list
(make source
(src (make continuous-src (wavelength 6.5) (width 20)))
(component Hz)
(center 0 0)
(size 0 0))))
; ---------------------------------------------
(set! pml-layers (list
(make pml (thickness dpml) (direction X))))
(set! resolution 20)
(run-until 50 (at-beginning output-epsilon)
(at-every 2 (output-png Hz "-Zc dkbluered")))
Best wished,
JL Liu
2008-12-28
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