Just calling (restart-fields) and calling (set! k-point ...) is not
enough to change the k-point, because you haven't told the fields
object to re-initialize its boundary conditions. You need to either
restart Meep entirely with (reset-meep) or, more efficiently, call
(restart-fields) and (change-k-point! k-point ...).
On Jun 16, 2010, at 4:51 PM, Eric CASSAN wrote:
Dear Steven
thanks again for the Meep software.
I try to use it to calculate dispersion diagrams. I do not
understand where is the mistake I do.
With the Bragg1.txt file, I find the dispersion diagram of a Bragg
mirror (no problem: same result as with the MPB: see image file).
In the second file, I try to manage my-self the list of k points,
and, in my opinion, I should obtain the same result.
I prefer this second option, because I would like doing harminv at
several locations.
Regarding these questions, I have seen the archive mailing list and
I have tried to use your answers.
I do not understand where is the problem. I have no error message,
but I obtain the same frequency solution for all k points, just as
though the Bloch periodic condition would not be taken into account
properly.
Thank you for your help.
With best regards,
Eric
===================================================
Eric CASSAN
Institut d'Electronique Fondamentale (UMR CNRS 8622)
Bâtiment 220 de l'Université Paris-Sud-11 (UPS11)
91405, Orsay, France
Phone : + 33 1 69 15 78 52 / 06 47 93 13 15
===================================================
<Bragg_diagram.jpg>
;;; Calculation of the dispersion diagram of a Bragg mirror using Meep
;;; Use of the run-k-points function
(define eps_core (* 2.65 2.65))
(define eps_clad (* 1.45 1.45))
(define core (make dielectric (epsilon eps_core)))
(define clad (make dielectric (epsilon eps_clad)))
(define periode 288.0) ;; période physique du BRAGG (en nm)
(define-param W (/ 500.0 periode))
(define lclad (/ 100.0 periode))
(define lcore (/ 188.0 periode))
(define-param sy 20.0)
(define-param dpml 1)
(set! geometry-lattice (make lattice (size 1 sy no-size)))
(set! default-material clad)
(set! geometry
(list
(make block (center 0 0 0) (size lcore W no-size)
(material core))
)
)
(set-param! resolution 20)
(set! subpixel-tol 1e-6)
(set! pml-layers (list (make pml (direction Y) (thickness dpml))))
(define-param fcen 0.22)
(define-param df 0.44)
(set! sources (list
(make source (src (make gaussian-src (frequency fcen)
(fwidth df))) (component Hz) (center -0.18247233 0.579152733))
(make source (src (make gaussian-src (frequency fcen)
(fwidth df))) (component Hz) (center 0.3023 0.20033))
(make source (src (make gaussian-src (frequency fcen)
(fwidth df))) (component Hz) (center 0.4123 -0.151284))
(make source (src (make gaussian-src (frequency fcen)
(fwidth df))) (component Hz) (center 0.22123 0.251284))
(make source (src (make gaussian-src (frequency fcen)
(fwidth df))) (component Hz) (center 0.3823 -0.91284))
)
)
(define-param k-interp 20)
(run-k-points 300 (interpolate k-interp (list (vector3 0 0 0)
(vector3 0.5 0 0))))
;;; Calculation of the dispersion diagram of a Bragg mirror using Meep
;;; I try to manage my-self the k points => no satisfying result
(define eps_core (* 2.65 2.65))
(define eps_clad (* 1.45 1.45))
(define core (make dielectric (epsilon eps_core)))
(define clad (make dielectric (epsilon eps_clad)))
(define periode 288.0) ;; période physique du BRAGG (en nm)
(define-param W (/ 500.0 periode))
(define lclad (/ 100.0 periode))
(define lcore (/ 188.0 periode))
(define-param sy 20.0)
(define-param dpml 1)
(set! geometry-lattice (make lattice (size 1 sy no-size)))
(set! default-material clad)
(set! geometry
(list
(make block (center 0 0 0) (size lcore W no-size)
(material core))
)
)
(set-param! resolution 20)
;;(set! subpixel-tol 1e-6)
(set! pml-layers (list (make pml (direction Y) (thickness dpml))))
(define-param fcen 0.2)
(define-param df 0.5)
(set! sources (list
(make source (src (make gaussian-src (frequency fcen)
(fwidth df))) (component Hz) (center -0.18247233 0.579152733))
(make source (src (make gaussian-src (frequency fcen)
(fwidth df))) (component Hz) (center 0.3023 0.20033))
(make source (src (make gaussian-src (frequency fcen)
(fwidth df))) (component Hz) (center 0.4123 -0.151284))
(make source (src (make gaussian-src (frequency fcen)
(fwidth df))) (component Hz) (center 0.22123 0.251284))
(make source (src (make gaussian-src (frequency fcen)
(fwidth df))) (component Hz) (center 0.3823 -0.91284))
)
)
(define-param k-interp 10)
(define k-points (interpolate k-interp (list (vector3 0 0 0)
(vector3 0.5 0 0))))
(map (lambda (k1)
(set! k-point k1)
(print "k-point=")
(print k1 "\n")
(print "\n")
(run-until 300
(after-sources (harminv Hz (vector3
-0.18247233 0.579152733 0.0) fcen df))
)
(restart-fields)
)
k-points
)
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