Re: [Meep-discuss] transmission larger than 1
Thank you so much Mr/Mrs Sang Soon Oh I have tried your suggestion and get the better result. But, it is still a little bit confusing. I still see the transmission coefficient with value 1.3. There are nine values of frequency with value between 1.1 and 1.3. All of them are lower frequency. I have tried to make my simulation better by increasing resolution from 20 to 40, and size of computational cell two times. Is this a numerical or physical error? What can I do to make it better? with regard Andika Asyuda ___ Dapatkan alamat Email baru Anda! Dapatkan nama yang selalu Anda inginkan sebelum diambil orang lain! http://mail.promotions.yahoo.com/newdomains/id/___ meep-discuss mailing list meep-discuss@ab-initio.mit.edu http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss
Re: [Meep-discuss] transmission larger than 1
Hello, You shouldn't divide the right edge flux by the left edge flux, because the left one is a summation of left-going (incident) flux and right-going (reflected) flux with minux sign. In order to calculate transmission, you have to obtain correct incident flux. To do that, you need to calculate twice like the case of Transmission spectrum around a waveguide bend in the MEEP tutorial. Sang Soon - Original Message - From: andika asyuda To: meep-discuss@ab-initio.mit.edu Sent: Thursday, September 04, 2008 2:17 AM Subject: [Meep-discuss] transmission larger than 1 Good night meep user I encountered a problem about meep simulation about periodic dielectric, sequence of hole at a block of silicon. I calculate flux at 3 points, the left edge (near the source) , center, and right edge. I calcuate transmission by divide the value of flux at center and left edge with the right edgeI got the surprising result because I saw there some frequencies with transmission value larger than 1. I hope some one can tell me what my mistake is Thank you so much for the help. I provide my code as following ; Some parameters to describe the geometry: (define-param eps 11.9) ; dielectric constant of waveguide (define-param w 1.43) ; width of waveguide (define-param r 0.26) ; radius of holes (define-param d 1.4) ; defect spacing (ordinary spacing = 1) (define-param N 5) ; number of holes on periodic mirror (define-param Ni 4) ; number of holes on inside cavity (define-param No 3) ; number of holes on outside defect ; The cell dimensions (define-param sy 6) ; size of cell in y direction (perpendicular to wvg.) (define-param pad 2) ; padding between last hole and PML edge (define-param dpml 1) ; PML thickness (define sx (+ (* 2 (+ pad dpml N Ni No)) d -1)) ; size of cell in x direction (set! geometry-lattice (make lattice (size sx sy no-size))) (set! geometry (append ; combine lists of objects: (list (make block (center 0 0) (size infinity w infinity) (material (make dielectric (epsilon eps) (geometric-object-duplicates (vector3 1 0) 0 (- N 1) (make cylinder (center (+ (/ d 2) Ni) 0) (radius r) (height infinity) (material air))) (geometric-object-duplicates (vector3 -1 0) 0 (- N 1) (make cylinder (center (- (/ d -2) Ni) 0) (radius r) (height infinity) (material air))) (geometric-object-duplicates (vector3 1 0) 0 (- Ni 1) (make cylinder (center (/ d 2) 0) (radius r) (height infinity) (material air))) (geometric-object-duplicates (vector3 -1 0) 0 (- Ni 1) (make cylinder (center (/ d -2) 0) (radius r) (height infinity) (material air))) (geometric-object-duplicates (vector3 1 0) 0 (- No 1) (make cylinder (center (+ (/ d 2) Ni N) 0) (radius r) (height infinity) (material air))) (geometric-object-duplicates (vector3 -1 0) 0 (- No 1) (make cylinder (center (- (/ d -2) Ni N) 0) (radius r) (height infinity) (material air) (set! pml-layers (list (make pml (thickness dpml (set-param! resolution 20) (define-param fcen 0.25) ; pulse center frequency (define-param df 0.2) ; pulse width (in frequency) (define-param nfreq 500) ; number of frequencies at which to compute flux (set! sources (list (make source (src (make gaussian-src (frequency fcen) (fwidth df))) (component Ey) (center (+ (/ d 2) Ni N No r 1) 0) (size 0 w (set! symmetries (list (make mirror-sym (direction Y) (phase -1 (define trans ; transmitted flux (add-flux fcen df nfreq (make flux-region (center (+ (/ d 2) Ni N No r) 0) (size 0 (* w 2) (define trans2 ; transmitted flux (add-flux fcen df nfreq (make flux-region (center 0 0) (size 0 (* w 2) (define trans3 ; transmitted flux (add-flux fcen df nfreq (make flux-region (center (* (+ (/ d 2) Ni N No r) -1) 0) (size 0 (* w 2) (run-sources+ (stop-when-fields-decayed 50 Ey (vector3 (* (+ (/ d 2) Ni N No r) -1) 0) 1e-3) (at-beginning output-epsilon) (during-sources
[Meep-discuss] transmission larger than 1
Good night meep user I encountered a problem about meep simulation about periodic dielectric, sequence of hole at a block of silicon. I calculate flux at 3 points, the left edge (near the source) , center, and right edge. I calcuate transmission by divide the value of flux at center and left edge with the right edgeI got the surprising result because I saw there some frequencies with transmission value larger than 1. I hope some one can tell me what my mistake is Thank you so much for the help. I provide my code as following ; Some parameters to describe the geometry: (define-param eps 11.9) ; dielectric constant of waveguide (define-param w 1.43) ; width of waveguide (define-param r 0.26) ; radius of holes (define-param d 1.4) ; defect spacing (ordinary spacing = 1) (define-param N 5) ; number of holes on periodic mirror (define-param Ni 4) ; number of holes on inside cavity (define-param No 3) ; number of holes on outside defect ; The cell dimensions (define-param sy 6) ; size of cell in y direction (perpendicular to wvg.) (define-param pad 2) ; padding between last hole and PML edge (define-param dpml 1) ; PML thickness (define sx (+ (* 2 (+ pad dpml N Ni No)) d -1)) ; size of cell in x direction (set! geometry-lattice (make lattice (size sx sy no-size))) (set! geometry (append ; combine lists of objects: (list (make block (center 0 0) (size infinity w infinity) (material (make dielectric (epsilon eps) (geometric-object-duplicates (vector3 1 0) 0 (- N 1) (make cylinder (center (+ (/ d 2) Ni) 0) (radius r) (height infinity) (material air))) (geometric-object-duplicates (vector3 -1 0) 0 (- N 1) (make cylinder (center (- (/ d -2) Ni) 0) (radius r) (height infinity) (material air))) (geometric-object-duplicates (vector3 1 0) 0 (- Ni 1) (make cylinder (center (/ d 2) 0) (radius r) (height infinity) (material air))) (geometric-object-duplicates (vector3 -1 0) 0 (- Ni 1) (make cylinder (center (/ d -2) 0) (radius r) (height infinity) (material air))) (geometric-object-duplicates (vector3 1 0) 0 (- No 1) (make cylinder (center (+ (/ d 2) Ni N) 0) (radius r) (height infinity) (material air))) (geometric-object-duplicates (vector3 -1 0) 0 (- No 1) (make cylinder (center (- (/ d -2) Ni N) 0) (radius r) (height infinity) (material air) (set! pml-layers (list (make pml (thickness dpml (set-param! resolution 20) (define-param fcen 0.25) ; pulse center frequency (define-param df 0.2) ; pulse width (in frequency) (define-param nfreq 500) ; number of frequencies at which to compute flux (set! sources (list (make source (src (make gaussian-src (frequency fcen) (fwidth df))) (component Ey) (center (+ (/ d 2) Ni N No r 1) 0) (size 0 w (set! symmetries (list (make mirror-sym (direction Y) (phase -1 (define trans ; transmitted flux (add-flux fcen df nfreq (make flux-region (center (+ (/ d 2) Ni N No r) 0) (size 0 (* w 2) (define trans2 ; transmitted flux (add-flux fcen df nfreq (make flux-region (center 0 0) (size 0 (* w 2) (define trans3 ; transmitted flux (add-flux fcen df nfreq (make flux-region (center (* (+ (/ d 2) Ni N No r) -1) 0) (size 0 (* w 2) (run-sources+ (stop-when-fields-decayed 50 Ey (vector3 (* (+ (/ d 2) Ni N No r) -1) 0) 1e-3) (at-beginning output-epsilon) (during-sources (to-appended hz (at-every 0.4 output-hfield-z (display-fluxes trans trans2 trans3) ; print out the flux spectrum with regard Andika Asyuda - Dapatkan alamat Email baru Anda! Dapatkan nama yang selalu Anda inginkan sebelum diambil orang lain!___ meep-discuss mailing list meep-discuss@ab-initio.mit.edu http://ab-initio.mit.edu/cgi-bin/mailman/listinfo/meep-discuss
