光栅布局在大多数情况下是周期性
结构。OptiFDTD中有两种实现周期性布局的方法:PBG编辑器和VB脚本。本课将重点介绍以下功能:
)9nW`d+ •使用VB脚本生成光栅(或周期性)布局。
kU/MvoV •光栅布局
模拟和后处理分析
yn\c;Z 布局layout
Sh(ys*y> 我们将模拟如图1所示的二维光栅布局。
+ Tp% * 图1.二维光栅布局
M)#9Q=< ;d}>8w&tfy 用VB脚本定义一个2D光栅布局
FygNWI ' Q#3}AO 步骤:
Z;G*wM" 1 通过在
文件菜单中选择“New”,启动一个新项目。
2OJlE)
. 2 在“Wafer Properties”对话框中设置以下
参数 |J!mM<*K Wafer Dimensions:
Zye04&x9k Length (mm): 8.5
$l*?Ce: Width (mm): 3.0
m538p.(LIR nook/ 7] 2D wafer properties:
w( V%EEk Wafer refractive index: Air
Hl}lxK,] 3 点击 Profiles 与 Materials.
2H%lN` av!;k2" 在“Materials”中加入以下
材料:
p/(Z2N" Name: N=1.5
)zxb]Pg+ Refractive index (Re:): 1.5
pL,XHR@Iv
?^Aj\z> Name: N=3.14
<q=Zg7zB Refractive index (Re:): 3.14
)G)6D"5,+G trDw|WA 4.在“Profile”中定义以下轮廓:
)!-gT Name: ChannelPro_n=3.14
y-26\eY^P 2D profile definition, Material: n=3.14
OM1Z}%J q7lC}'2fu Name: ChannelPro_n=1.5
H[hJUR+# 2D profile definition, Material: n=1.5
9>4 #I3 znE1t%V 6.画出以下波导结构:
p(pfJ^/:( a. Linear waveguide 1
|^-D&C(Eu Label: linear1
y!1X3X,V Start Horizontal offset: 0.0
MU$tX Start vertical offset: -0.75
vCi`htm% End Horizontal offset: 8.5
-u@ ^P7 End vertical offset: -0.75
^mq(j_E. Channel Thickness Tapering: Use Default
fJr
EDj4( Width: 1.5
B/l^=u+- Depth: 0.0
~qqxHymc Profile: ChannelPro_n=1.5
\=WPJm`p ;J|t-$Z b. Linear waveguide 2
_h<rVcl!wX Label: linear2
_6fy'%J=U Start Horizontal offset: 0.5
Q`*U U82! Start vertical offset: 0.05
PR"x&JG@ End Horizontal offset: 1.0
n5C,Z!)z End vertical offset: 0.05
UdrgUqq) Channel Thickness Tapering: Use Default
kS_#8I Width: 0.1
)tBz=hy# Depth: 0.0
9.(|ri Profile: ChannelPro_n=3.14
b4L7]& 9xbT?$^ 7.加入水平平面波:
oIO@# Continuous Wave Wavelength: 0.63 General:
E@C.}37R Input field Transverse: Rectangular
%!t9)pNc X Position: 0.5
a2.6S./ Direction: Negative Direction
/%;J1{O Label: InputPlane1
h rSH)LbJ 2D Transverse:
U Y*`R Center Position: 4.5
1av#u:jy~> Half width: 5.0
f5F-h0HF`[ Titlitng Angle: 45
JL
G!;sov Effective Refractive Index: Local Amplitude: 1.0
Tl yyJ{~ 图2.波导结构(未设置周期)
q>(?Z#sB GcN}I=4| 8.单击“Layout Script”快捷工具栏或选择
仿真菜单下的“Generate Layout Script…”。这一步将把布局对象转换为VB脚本代码。
FNUs
.d" 将Linear2代码段修改如下:
m
Z
+dr[ Dim Linear2
atpHv**D<i for m=1 to 8
Q Set Linear2 = WGMgr.CreateObj ( "WGLinear", "Linear2"+Cstr(m) )
HlX~a:.7 Linear2.SetPosition 0.5+(m-1)*1.0, 0.05, 1+(m-1)*1.0, 0.05
O\f`+Q`0 Linear2.SetAttr "WidthExpr", "0.1"
|a03SZx Linear2.SetAttr "Depth", "0"
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