Dear Steven/Meep users,
I generated a gaussian pulse (having Gaussian spatial envelope) according to some of the posts in the forum. But when I introduce a beam angle for an oblique incidence, the generated Gaussian pulse is not that good (Actually there are two pulses as mirror images from the source plane.) So keep the source line little away from the PML to absorb the unwanted pulse (propagating in same angle to -y direction). But as you can see in the attached image there is a unwanted broadening towards the source line of the useful pulse as well. http://www.picturepush.com/public/1883197 thanks for any help. Here is my ctl file, (define-param sx 30) ; width of the block without the PML region (define-param sy 50) ; height of the block without the PML region (define-param dpml 5) ; PML thickness (define-param bk1 sx) ; width of the block 1 (neutral dielectric medium (define-param bk2 5) ; width of the block 2 (active - gain/loss medium) (define-param fcen 0.5) ;center frequency- corresponds to 2um wavelength (define-param df 0.2) ;frequency width (define-param eps 4) ;epsilon value for block 1 (define-param n (sqrt eps)) ; IOR for the block 1 ;Need to define the dielectric parameters for the block 2 (gain/loss medium) (define-param half-space? false); ;Creating the simulation region with the PML layers (set! geometry-lattice (make lattice (size (+ sx dpml) (+ sy dpml) no-size))) ;Creating the block 1 and block 2 (set! geometry ( if half-space? (list (make block (center (0 0)) (size sx sy infinity) (material (make dielectric (epsilon eps)))) (make block (center (- (* 0.5 sx) (* -0.5 dk2))) (size dk2 sy infinity) (material air))) ;Later this material should be set to the Lossy/Gainy material type (list (make block (center 0 0) (size sx sy infinity) (material (make dielectric (epsilon eps))))))) (set! pml-layers (list (make pml (thickness dpml)))) (set-param! resolution 10) (use-output-directory) (define-param source-component Ez) (define-param theta_deg 4); this is the launch angle ;theta goes from 0 (+Y prop) to 90 (+X prop) (define theta_rad (/ (* pi theta_deg) 180)); change theta to radians (define ((pw-amp k sigma x0) x) (exp (- (* 0+1i (vector3-dot k (vector3+ x x0))) (/ (vector3-dot (vector3+ x x0) (vector3+ x x0)) (* 2 sigma sigma))))) (define-param kdir (vector3 (sin theta_rad) (cos theta_rad))); direction of k (define k (vector3-scale (* 2 pi fcen n) (unit-vector3 kdir))); set k to be proper length in direction of kdir (set! sources (list (make source (src (make gaussian-src (frequency fcen) (fwidth df) )) (component source-component) (center 0 -20) (size sx 0) (amp-func (pw-amp k 0.5 (vector3 10 0)))))) (run-sources+ 100 (at-beginning output-epsilon) (at-every 1.0 (output-png Ez "-Zc dkbluered")))
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