Hello everyone,
I am modeling in MEEP 1d photonic crystal cavity in SOI. In 2d calculations I
have not got any problem with that. But when I extend my model to 3d, problems
came. When I run program with 4 or more pairs of mirror (N=5) I cannot find
resonant mode. Or if I try compute transmission, flux1: = +inf.0. ?? I do not
know what that mean. I have checked symmetry, distance source from PhC, and
nothing help. My script is below, if someone can help me I will be really
grateful.
Wishes
Szymon
;1d photonic crystal cavity in SOI
;some parameters to describe the geometry:
(define-param nsi 3.48) ; index of waveguide
(define-param nsio2 1.46); index of sio2
(define-param w 0.4) ;width of waveguide
(define-param H 0.2) ;size of defect
(define-param L 0.09) ;defect spacing
(define-param D 0.4) ;cavity size
(define-param N 5) ;number of defectys on either side of defect
(define-param p (+ H L)); period
(define-param h 0.65); depth of etch
(define-param hw 0.36); hight of waveguide
(define-param sisub 1); thickness of Si substrate
(define-param sio2 1.5); thickness of SiO2 buffer layer
(define-param si 0.36); thickness of Si waveguide
(define-param pad 10) ;padding between last defect and PML edge
(define-param dpml 2) ; PML thickness
(define-param dpmlz 2); PML thickness in Z direction
;The cell dimensions
(define-param sx (+ w 7 (* 2 dpml))) ;size of cell in x direction
(perpendicular to wvg.)
(define-param sy (* 2 (+ sio2 (* hw 0.5) dpml))); size of cell in z direction
(hight)
(define-param sz (+ (* 2 (+ pad dpml (* N p))) D)) ;size of cell in x direction
(propagation diraction)
(set! geometry-lattice (make lattice (size sx sy sz)))
(set! geometry
(append
(list
(make block (center 0 (+ (* 0.5 hw) (* 0.5 sio2)) 0)
(size infinity sio2 infinity)
(material (make dielectric (index nsio2))))
(make block (center 0 0 0) (size w hw infinity)
(material (make dielectric (index nsi)))))
(geometric-object-duplicates (vector3 0 0 p) 0 (- N 1)
(make block (center 0 (+ (* -0.5 hw) (* 0.5 h)) (+ (* H
0.5) (* D 0.5))) (size w h L)
(material air)))
(geometric-object-duplicates (vector3 0 0 (* p -1)) 0 (- N 1)
(make block (center 0 (+ (* -0.5 hw) (* 0.5 h)) (+ (* H
-0.5) (* D -0.5))) (size w h L)
(material air)))))
(set! pml-layers (list (make pml (thickness dpml))))
(set-param! resolution 10)
(define-param fcen 0.65) ;pulse center frequency
(define-param df 0.2) ;pulse width (in frequency)
(define-param nfreq 500); number of frequencies at which to compute flux
;false = transmission spectrum, true = resonant mode;
(define-param reso-mode? false)
(if reso-mode?
(begin
(set! sources (list
(make source
(src (make gaussian-src (frequency fcen)
(fwidth df)))
(component Hy) (center 0 0 0 ))))
)
(begin
(set! sources (list
(make source
(src (make gaussian-src (frequency fcen)
(fwidth df)))
(component Hx)
(center 0 0 (+ dpml 0.05 (* -0.5 sz)))
(size w hw 0))))
))
(if reso-mode?
(begin
(set! symmetries
(list (make mirror-sym (direction X) (phase -1))
(make mirror-sym (direction Z) (phase
-1))))
)
(begin
(set! symmetries
(list (make mirror-sym (direction X) (phase +1))))
))
(if reso-mode?
(begin
)
(begin
(define trans ; transmitted flux
(add-flux fcen df nfreq
(make flux-region
(center 0 0 (- (* 0.5 sz) dpml 0.5))
(size (* 2 w) (* 2 hw) 0)
(direction Z))))
)
)
(if reso-mode?
(begin
(run-sources+ 400
(at-beginning output-epsilon)
(after-sources (harminv Hy (vector3 0 0 0) fcen df)))
(run-until (/ 1 fcen) (at-every (/ 1 fcen 20) output-hfield-y))
)
(begin
(run-sources+ (stop-when-fields-decayed
50 Hx
(vector3 0 0 (- (* 0.5 sz) dpml 0.5))
1e-3)
(at-beginning output-epsilon)
(during-sources
(in-volume (volume (center 0 0 0) (size 0 0 sz))
(to-appended "ez-slice" (at-every 0.4
output-efield-z)))))
))
(if reso-mode?
(begin
)
(begin
(display-fluxes trans) ;print out the flux spectrum
)
)
___________
Szymon Lis
Photonics Group
Faculty of Microsystem Electronics and Photonics
Wroclaw University of Technology
ul. Janiszewskiego 11/17, 50-372 Wroclaw, POLAND
Tel. +48 (71) 320 3735
Fax. +48 (71) 328 3504
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