Hello meep-discussion list,
I'm trying to simulate a 3D rectangular waveguide (one could say I
should do it in 2D but it's just some steps from what I really want to
do...). My .ctl - file looks a follows (I'm not sure if I messed with
the meep units and the cutoff freqeuncy):
------------------snip----------------------------------------------------------
; define some constants and measures
(define-param length_z 24) ; already added some space for pml
(define-param width_x 7)
(define-param height_y 1)
(define-param pml-size 2.0)
(define-param inner_block 5)
(define-param inner_eps 4)
(define-param center_freq 0.5) ; with a = 1m and c = 1 I get w_c =
pi*c/width_x < 0.5
(define-param freq-samples 25)
(define-param df 0.1)
; create a lattice with proper size
(set! geometry-lattice (make lattice (size width_x height_y length_z)))
(define-param no-block? false) ; to get transmission spectra one can set
this variable from the command-line
(set! geometry
(if no-block? ;if the variable is set from outside there are two
implementations!
(list
(make block
(center 0 0)
(size width_x height_y length_z)
(material (make dielectric (epsilon 1)))))
(list
(make block
(center 0 0)
(size width_x height_y length_z)
(material (make dielectric (epsilon 1))))
(make block
(center 0 0)
(size width_x height_y inner_block)
(material (make dielectric (epsilon inner_eps)))))))
(define-param absolute-flux-position (-(- (/ length_z 2) 1) pml-size) )
; create a source
(set! sources (list (make source
(src (make gaussian-src
(frequency center_freq)(width 6)))
(component Ey)
(center (+ absolute-flux-position 1) 0)
(size 0 (* height_y 0.95) 0)))); this source should
not touch the boundaries
; apply the pml in z - direction (the others will be handled later)
(set! pml-layers
(list
(make pml (thickness pml-size) (direction Z))
(make pml (thickness 0) (direction X)); electric boundary in X direction
(make pml (thickness 0) (direction Y)))) ; electric boundary in Y
direction
; create Flux planes (like ports, but no input!)
(define trans ; transmitted flux
(add-flux center_freq df freq-samples
(make flux-region
(center 0 0 absolute-flux-position)
(size width_x height_y 0))))
(define refl ; reflected flux
(add-flux center_freq df freq-samples
(make flux-region
(center 0 0 (- absolute-flux-position 0))
(size width_x height_y 0))))
; boundary conditions for hollow guide
;(init-fields) ; fields need no init if fluxes added before; not sure if
those are needed (all metallic)
;(meep-fields-set-boundary fields High Y Metallic)
;(meep-fields-set-boundary fields Low Y Metallic)
;(meep-fields-set-boundary fields High X Metallic)
;(meep-fields-set-boundary fields Low X Metallic)
; set the resolution to some value
(set! resolution 20)
; if there is an older computation load the spectrum for the input
(produces bad error when file not there!)
(if (not no-block?) (load-minus-flux "refl-flux" refl))
; really start the simulation
(run-sources+ 100
(at-beginning output-epsilon)
(to-appended "ey" (at-every 0.6 output-efield-y)))
; save the flux for later transmission tricks
(if no-block? (save-flux "refl-flux" refl))
; show the values to get them into matlab
(display-fluxes trans refl)
--------------------snap-----------------------------------------------
so far this script is partly adopted from the tutorial's page. Now
running this script with:
~> meep no-block?=true waveguide.ctl | tee out.log
and extracting some graphics via
~> h5topng -0y0 -t 100 -Zc bluered waveguide-ey.h5 -o Pic_y.png
I only get black bricks (the same for x and z direction) in
Pic_x,y,z.png. Whats my mistake? Is the source somehow not working
right? I think putting in a single e_y component sould somehow exite the
TE_10 - Mode. Any Ideas? Thanks in advance for your help,
greetings
Tobias
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