As a MEEP-user of one month, I post for the first time.
(I sent this posting a few days ago, but it was not posted probably because I
attached a gif movie file that came out of the run. This time I send it again
without the attachement.)
In the ctl file below, I attemp to generate a plane wave pulse propagating
along x. The electric field is polarized along z.
Here, I have two problems.
(1) The plane wave propagates along both +x and -x directions. Is there a way
to generate a plane wave propagating along only +x direction?
(2) The second problem is about the symmetry and boundary conditions. If I
remove the symmetry statement from the ctl file below, I can generate the
perfect plane wave pulse. But with the symmetry statement below, I always have
residuary field after the source pulse propagated out. I attached a gif file
(z=0 cross section) that was made with this run.
I would appreciate your advice.
Seong Kyu Kim
; Lattice and Boundaries ------------------------------------------------------
(define-param sx 1.0) ; the length of x of the lattice, not including PML
(define-param sy 1.0) ; the length of y of the lattice, not including PML
(define-param sz 1.0) ; the length of z of the lattice, not including PML
(define-param dpml 0.1) ; thickness of PML layers
(set! geometry-lattice (make lattice (size (+ sx (* 2 dpml)) sy sz)))
(set-param! resolution 100)
(set! pml-layers (list (make pml (thickness dpml) (direction X))))
(set! k-point (vector3 0 0 0))
; -----------------------------------------------------------------------------
; Source - plane wave ---------------------------------------------------------
; pw-amp is a function that returns the amplitude exp(ik(x+x0)) at a
; given point x. (We need the x0 because current amplitude functions
; in Meep are defined relative to the center of the current source,
; whereas we want a fixed origin.) Actually, it is a function of k
; and x0 that returns a function of x ...
(define ((pw-amp k x0) x) (exp (* 0+1i (vector3-dot k (vector3+ x x0)))))
(define-param fcen 2.0); pulse center frequency
(define-param df 1.0) ; frequency bandwidth
(define-param kdir (vector3 1 0 0 ) ) ; direction of k (length is irrelevant)
(define k (vector3-scale (* 2 pi fcen)
(unit-vector3 kdir))) ; k with correct length
(set! sources
(list (make source
(src (make gaussian-src (frequency fcen) (fwidth df)))
(component Ez) (center (* -0.3 sx) 0 0) (size 0 sy sz)
(amp-func (pw-amp k (vector3 (* -0.3 sx) 0 0)))) ))
; ------------------------------------------------------------------------------
; symmetries -------------------------------------------------------------------
(set! symmetries (list (make mirror-sym (direction Y))
(make mirror-sym (direction Z) (phase -1))))
; ----------------------------------------------------------------------------
; Run and outputs -------------------------------------------------------------
(set! filename-prefix false)
(set! output-single-precision? true)
(define-param T 10) ; run time
(run-until T (at-beginning output-epsilon)
(to-appended "ez" (at-every 0.1 output-efield-z)))_______________________________________________
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