Thanks a lot Marell and Steven, but I am still confused.
I am trying to putsources inside a PC cavity. It's difficult but it's not
science fiction (Appl. Phys. Lett., 89, 211117 (2006)). I am interested in
coherent nonlinear phenomena, thus I need to be sure about normalization
procedures. And I'd like to get information about the source emission spectra
form inside the cavity.
I designed a PC "stripe" composed by 7 periods in the direction normal to light
propagation, with a cavity in the middle. I use exactly the same simulation
window and I move the light source inside and outside the PC cavity, keeping
the
monitor fixed.
With source outside the cavity, there are no problem: things running fine and
normalization works as expected (one simulation with PC and one with bulk
homogeneous material - no PC).
If I put the source inside the cavity I always get a kind of light
amplification
that it is not expected to be there.
Probably things are clearer with the attached image that shows the two spectra
with source inside (narrower red peak) and outside the cavity (wider black
data). Y Scales differ for one order of magnitude, and if I normalize the
spectra things get even worse, clearly...
Why I get this signal amplification? Is it because I am running a pure 2D
simulation?
Thanks for any suggestions!
Paolo.
Here below the revelant ctl code:
(define-param res 10)
(define-param rad 0.3)
(define-param numlayers 15)
(define-param dpml 3)
(define-param pad 2)
(define-param freq 0.4397)
(define-param defreq 0.2)
(define-param nfreq 1000)
(define-param fcen_h freq)
(define-param df_h defreq)
(define-param sx 24)
(define-param sy sx)
(define-param runtime 500)
(define-param sourcex (/ sx -3.5))
(define-param sourcey 0)
(define eps-averaging? true)
(set! pml-layers (list (make pml (thickness dpml))))
(set! resolution res)
(set! default-material (make dielectric (epsilon diel_slab)))
(set! geometry-lattice (make lattice (size sx sy no-size)))
(set! geometry
(append
(geometric-objects-duplicates (vector3 (/ (sqrt 3) 2) 0.5) (* -1
numlayers) numlayers
(geometric-objects-duplicates (vector3 (/ (sqrt 3) 2) -0.5) (* -1
numlayers) numlayers
(list (make cylinder (center 0 0)(radius rad)(height
infinity)(material (make dielectric(epsilon diel_hole))))
)))))
(set! geometry (append geometry (list
(make cylinder (center 0 0)(radius (* 1 rad))(height infinity)(material
(make dielectric (epsilon diel_slab))))
(make cylinder (center 0 1) (radius (* 1 rad))(height infinity)(material
(make dielectric (epsilon diel_slab))))
(make cylinder (center 0 -1)(radius (* 1 rad))(height infinity)(material
(make dielectric (epsilon diel_slab))))
(make block (center (- (/ sx 2) 3.5) 0) (size (+ dpml (* 4 pad)) sy)
(material (make dielectric (epsilon diel_slab))))
(make block (center (+ (/ sx -2) 3.5) 0) (size (+ dpml (* 4 pad)) sy)
(material (make dielectric (epsilon diel_slab))))
)))
(set! geometry (list
(make block (center 0 0) (size sx sy)(material (make dielectric (epsilon
diel_slab)))); for normalization
))
(set! sources (list (make source
(src (make gaussian-src (frequency freq)(fwidth defreq)))
(component Ex) (center sourcex sourcey) (size 0 0))))
(define trans
(add-flux freq defreq nfreq (make flux-region (center (- (/ sx 2) dpml pad) 0)
(size 0 (- sy dpml dpml pad))))
)
(run-sources+ runtime
(at-beginning output-epsilon)
; (at-every 25 output-efield-x)
(after-sources
(harminv Ex (vector3 (+ 0 sourcex) (+ 0 sourcey)) fcen_h df_h)
)
)
(display-fluxes trans)
________________________________
Da: Steven G. Johnson <[email protected]>
A: MEEP Discuss <[email protected]>
Inviato: Mer 19 gennaio 2011, 02:18:31
Oggetto: Re: [Meep-discuss] normalization
What property of the cavity are you trying to simulate?
e.g. are you simulating and experiment? In an experiment, the light source is
probably not within the photonic crystal. e.g. it may be coming from the air
outside a finite photonic crystal. In that case, you would normalize by the
incident power, which is the power measured in a simulation when you remove the
cavity AND the photonic crystal.
Other simulation golas will call for other normalizations.
--SGJ
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