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:
1{cF/ :o •使用VB脚本生成光栅(或周期性)布局。
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Z\=2D •光栅布局
模拟和后处理分析
?aTC+\= 布局layout
VRY@}>W' 我们将模拟如图1所示的二维光栅布局。
ab)ckRC 图1.二维光栅布局
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lb,P r<P? F 用VB脚本定义一个2D光栅布局
K@osD7- vt(n: Xk 步骤:
o?.VW/" 1 通过在
文件菜单中选择“New”,启动一个新项目。
i{Q,>Rt 2 在“Wafer Properties”对话框中设置以下
参数 +Bt%W%_X Wafer Dimensions:
\sW>Y#9] Length (mm): 8.5
J]48th0, Width (mm): 3.0
~G^+.>j w`#9Re 2D wafer properties:
V!+< Wafer refractive index: Air
f!GFRMM1 3 点击 Profiles 与 Materials.
2#UVpgX? %^"i\-*|S 在“Materials”中加入以下
材料:
1O)m(0tb[ Name: N=1.5
76c:*bZ Refractive index (Re:): 1.5
'q8:1i9\[ pg<cvok Name: N=3.14
md : Wx Refractive index (Re:): 3.14
^fS_h`B G(hnrRxn 4.在“Profile”中定义以下轮廓:
4}YHg&@\d% Name: ChannelPro_n=3.14
8N#.@\'kz. 2D profile definition, Material: n=3.14
O4a~(*f YsTF10 Name: ChannelPro_n=1.5
._'.F'd 2D profile definition, Material: n=1.5
brF) %x` '^2bC 6.画出以下波导结构:
{;JFoe+ a. Linear waveguide 1
_XI,z0( Label: linear1
/KO2y0` Start Horizontal offset: 0.0
Q b5vyV ` Start vertical offset: -0.75
H}1XK|K3#H End Horizontal offset: 8.5
N{!@M_C^%R End vertical offset: -0.75
x.(Sv]+[ Channel Thickness Tapering: Use Default
cI<T/~P Width: 1.5
c^,8eb7c Depth: 0.0
^7$Q" Profile: ChannelPro_n=1.5
8..g\ZT N\hHu6 b. Linear waveguide 2
P2U [PO Label: linear2
-li;w
tCS Start Horizontal offset: 0.5
w~e$ul(IQM Start vertical offset: 0.05
5 ^tetDz} End Horizontal offset: 1.0
+/#Lm#*nu% End vertical offset: 0.05
DwXSlsN3v Channel Thickness Tapering: Use Default
Rd1I$| Y Width: 0.1
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Depth: 0.0
@iYr<>iDZ Profile: ChannelPro_n=3.14
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tSSX<N PV/ hnVUl 7.加入水平平面波:
"/\-?YJjw Continuous Wave Wavelength: 0.63 General:
S%Z2J)H" Input field Transverse: Rectangular
KKw J=za X Position: 0.5
F4&`0y: Direction: Negative Direction
nqib`U@" Label: InputPlane1
lhFv2.qR 2D Transverse:
jsw0"d( Center Position: 4.5
l;;"v) C8 Half width: 5.0
W
-5wjc Titlitng Angle: 45
.W0;Vhw" Effective Refractive Index: Local Amplitude: 1.0
>=L<3W1 图2.波导结构(未设置周期)
H3BMN}K~ "nn>I}jK 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。
7{u1ynt 将Linear2代码段修改如下:
|%Ssb;M Dim Linear2
D{,
b|4 for m=1 to 8
/2]=.bLwz Set Linear2 = WGMgr.CreateObj ( "WGLinear", "Linear2"+Cstr(m) )
X&|y| Linear2.SetPosition 0.5+(m-1)*1.0, 0.05, 1+(m-1)*1.0, 0.05
V#d8fRm Linear2.SetAttr "WidthExpr", "0.1"
{ Em fw9L Linear2.SetAttr "Depth", "0"
o~p%ODH Linear2.SetAttr "StartThickness", "0.000000"
@-jI<g Linear2.SetAttr "EndThickness", "0.000000"
8$6^S{M3 Linear2.SetProfileName "ChannelPro_n=3.14"
1n+JHXR\ Linear2.SetDefaultThicknessTaperMode True
"@+r|x P&8QKX3
j^ 点击“Test Script”快捷工具栏运行修改后的VB脚本代码。生成光栅布局,布局如图3所示。
?h|w7/9 图3.光栅布局通过VB脚本生成
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