1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
|
; From the Meep tutorial: transmission around a 90-degree waveguide
; bend in 2d.
(define-param sx 16) ; size of cell in X direction
(define-param sy 32) ; size of cell in Y direction
(set! geometry-lattice (make lattice (size sx sy no-size)))
(define-param pad 4) ; padding distance between waveguide and cell edge
(define-param w 1) ; width of waveguide
(define wvg-ycen (* -0.5 (- sy w (* 2 pad)))) ; y center of horiz. wvg
(define wvg-xcen (* 0.5 (- sx w (* 2 pad)))) ; x center of vert. wvg
(define-param no-bend? false) ; if true, have straight waveguide, not bend
(set! geometry
(if no-bend?
(list
(make block
(center 0 wvg-ycen)
(size infinity w infinity)
(material (make dielectric (epsilon 12)))))
(list
(make block
(center (* -0.5 pad) wvg-ycen)
(size (- sx pad) w infinity)
(material (make dielectric (epsilon 12))))
(make block
(center wvg-xcen (* 0.5 pad))
(size w (- sy pad) infinity)
(material (make dielectric (epsilon 12)))))))
(define-param fcen 0.15) ; pulse center frequency
(define-param df 0.1) ; pulse width (in frequency)
(set! sources (list
(make source
(src (make gaussian-src (frequency fcen) (fwidth df)))
(component Ez)
(center (+ 1 (* -0.5 sx)) wvg-ycen)
(size 0 w))))
(set! pml-layers (list (make pml (thickness 1.0))))
(set-param! resolution 10)
(define-param nfreq 100) ; number of frequencies at which to compute flux
(define trans ; transmitted flux
(add-flux fcen df nfreq
(if no-bend?
(make flux-region
(center (- (/ sx 2) 1.5) wvg-ycen) (size 0 (* w 2)))
(make flux-region
(center wvg-xcen (- (/ sy 2) 1.5)) (size (* w 2) 0)))))
(define refl ; reflected flux
(add-flux fcen df nfreq
(make flux-region
(center (+ (* -0.5 sx) 1.5) wvg-ycen) (size 0 (* w 2)))))
; for normal run, load negated fields to subtract incident from refl. fields
(if (not no-bend?) (load-minus-flux "refl-flux" refl))
(run-sources+
(stop-when-fields-decayed 50 Ez
(if no-bend?
(vector3 (- (/ sx 2) 1.5) wvg-ycen)
(vector3 wvg-xcen (- (/ sy 2) 1.5)))
1e-3)
(at-beginning output-epsilon))
; for normalization run, save flux fields for refl. plane
(if no-bend? (save-flux "refl-flux" refl))
(display-fluxes trans refl)
|
