Hello,
I use the following code snippet to generate a Gaussian (spatial) + sin**2
(time) source, also taken from this list and adapted. It's pretty
self-explanatory, maybe you find it useful. It generates a (focus of a)
gaussian beam of width 1 in +y direction.
Regards,
Georg
; %%%%%%%%%%%% source %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
(define-param phasephi 0.500)
; spatial dependence - gaussian
(define ((my-amp sigma k) x)
(exp (- (* 0+2i pi (vector3-dot k x))
(/ (vector3-dot x x) (* 2 sigma sigma)))))
; time dependence
(define (laser_2 t)
(define tau 1.9486509 ) ; 6.5 fs
(define frequency 1.25) ; 800 nm
(define phase (* 2 pi (+ 0.50 0.25 phasephi) )) ; cosine+=0.
(if (< t (* 2 tau) )
(* (sin (+ (* 2 pi frequency (- t tau) ) phase)) 1. (expt (sin (/ (*
pi t) (* 2 tau)) ) 2) )
0.
)
)
(set! sources (list
; "laser"
(make source
(src (make custom-src (src-func laser_2)) )
(component Ex) (center 0 0 )
(size 06 00 05.5) (amplitude 1.) ; size (and box)
should be > width!
(amp-func (my-amp 1. (vector3 0 1 0))) ; set width here
)
; the second source is for aesthetic reasons, to cancel the "beam" in
-y direction
(make source
(src (make custom-src (src-func laser_2)) )
(component Hz) (center 0 0)
(size 06 00 05.5) (amplitude -1.)
(amp-func (my-amp 1. (vector3 0 1 0)))
)
)
)
On Wed, Jan 26, 2011 at 2:58 PM, Geethaka Devendra <gcdeven...@gmail.com>wrote:
> Hi Prof Steven and Meep users,
>
> Can someone please give me an example how to use the amp-func of the source
> to generate a gaussian source, which has a gaussian spatial profile. I read
> some of the earlier posts about using the amp-func, but didn't really
> understand the concept with k-vector and width. Can someone please explain
> me this and possibly show me an example, I think this feature of the source
> is really handy, but not knowing how to use is most frustrating.
>
> Thanks alot
> Geeth
>
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