Hi, Everyone, I am trying to study field ehancement in a 40nm hole at a nanowire fiber core with its diameter around 450 nm, and the enhanced field's near field transmission in the free space after outputing from the fiber. From comsol, as shown in the attachment,I got two eigen modes. One has enhancement in the hole, which is in agreement with theory, another one just has enhancement at the interface,and the field in the center of the hole are very small.
However the mode I got from Meep, the field in the centre of the hole always
very low compared to that in the interface. I like to get the same correct
result to that from COMSOL with strong field enhancement in the hole. Could you
please help me to have a look at my code?Thanks.
Here I use X axis as guide propagation direction, thus Ez,and Ey should
transverse electric field, and Ex is the compnent in the propagation direction
if my understanding is correct. About the symmetry, could I use the rotational
symmetry to further reduce modelling time? I compare the results with and
without the symmetry introduced in my code, and get similar results. Thus I
thought my introduced symmetry should be right.
Is the results heavily dependent on resolution? I have down resolution to 1.6 nm
without any difference. The Meep pattern showed in the
attachement is output-dpwr, and the meep curve is output-tot-pwr from left1.h5.
Also I thought Ex shuld be very small, thus I use Ey or Ez as source but seems
the results did not have much difference. I am not sure if the line source
produced this problem. Your help is much thanked.
Yinlan from University of Adelaide
My code is listed:
(define-param fiber 450) ;set the diameter of the fiber
(define-param l 5) ;set the length of the fiber
(define-param guide 250) ;set the normalized value
(define-param dfiber (/ fiber guide)) ;normalize the diameter of fiber
(define-param MFD (* (/ dfiber 2) 0.9267)) ;set the MFD value
(define-param wlength (/ 1000 guide)) ;set the normalized wavelength of light
(define-param eps (* 2.0355 2.0355)) ;define the index of fiber
(define-param sx (* 1.7 l))
(define-param sy 4)
(define-param sz 4)
(define-param sc 4)
(set! geometry-lattice (make lattice (size sx sy sz)))
(define-param hole 20) ;set the diameter of the fiber
(define-param n_hole 1.0)
(define-param rhole (/ hole guide)) ;normalize the diameter of central hole
(set-param! force-complex-fields? true)
(set-param! eps-averaging? false)
(define-param no-inclined? false)
(set! geometry
(list
(make cylinder
(center (+ (* 0.5 l) (* -0.5 sx)) 0 0)
(radius (/ dfiber 2))
(height l )
(axis 1 0 0)
(material (make dielectric (epsilon eps))))
(make cylinder
(center (+ (* 0.5 l) (* -0.5 sx)) 0 0)
(radius rhole)
(height l)
(axis 1 0 0)
(material (make dielectric (epsilon 1))))
)
)
(define-param gauss? false)
(define-param fcen (/ 1 wlength))
(define-param df 0.1)
(define ((circular-amp w) r)
(if (> (vector3-norm r) (/ dfiber 2))
(* (exp (* -1 (/ (vector3-dot r r) (* w w)))) eps)
(exp (* -1 (/ (vector3-dot r r) (* w w))))))
(set! sources
(if (not gauss?)
(list
(make source
(src (make continuous-src (frequency fcen)(end-time 150) ))
(component Ez)
(center (+ 1 (* -0.5 sx)) 0 0)
(size 0 sy sz)
(amp-func (circular-amp MFD))))
(list
(make source
(src (make gaussian-src (frequency fcen) (fwidth df)))
(component Ez)
(center (+ 1 (* -0.5 sx)) 0 0)
(size 0 (/ dfiber 2) (/ dfiber 2))
;(amp-func (circular-amp MFD))
))))
(set! symmetries (list (make mirror-sym (direction Y)) (make mirror-sym
(direction Z) (phase -1))))
(set! pml-layers (list (make pml (thickness 0.7))))
(set-param! resolution 80)
(define-param nfreq 1) ; number of frequencies at which to compute flux
(run-until 150
(at-beginning output-epsilon)
(at-end
(to-appended "left1" (in-volume (volume (center (- 0.0003 (- l (* 0.5 sx))) 0 0)
(size 0 sc sc))
(synchronized-magnetic output-tot-pwr )))
(to-appended "right1" (in-volume (volume (center (- l (* 0.5 sx)) 0 0) (size 0
sc sc))
(synchronized-magnetic output-tot-pwr )))
)
(at-end output-dpwr)
)
<<attachment: 95-denergy-000024000_meep_3.jpg>>
<<attachment: 450nm-1um-40nm hole_curve_meep_3.jpg>>
<<attachment: 450nm-1um-40nm hole_curve_r_0.5_3.jpg>>
<<attachment: 450nm-1um-40nm hole_mode_r_0.5_3.jpg>>
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