The following lesson uses straight channel waveguide as an example.

Note:

•     The corresponding project file can be found in the Sample file folder,

Sample43_64bit_3D_Simulations_Getting_Started.fdt.

•     If you already familiar with layout creation, please open the example project and go to the step “Perform the 64Bit-FDTD FDTD Simulation”

•     Please see other tutorial lessons to get familiar with the Layout Designer features

Layout creation steps

StepAction
1Open OptiFDTD Waveguide layout Designer

From the Start menu, select Programs >Optiwave Software > OptiFDTD >

Waveguide Layout Designer. OptiFDTD_Designer window opens

2Create a new project

From the OptiFDTD_Designer File menu, select New. The Initial Properties dialog box appears

3Define the material(s) and waveguide profile(s) that will be used in the project Click Profiles and Materials button in the area in Initial Properties Dialog. The Profile Designer OptiFDTD opens,

Note: Profile Designer can also be opened independently at any time a.   In the directory under OptiFDTD_Designer1 of Profile Designer OptiFDTD, under Materials folder, right-click the Dielectric folder. A context menu appears. Select New, the Dielectric dialog box appears. By default the constant refractive index (Const Ref. Idx) is selected. Type the following information:

Name: n=1.5

Constant refractive index (isotropic) (Re): 1.5

Click Store to save this material, Material n=1.5 will be listed under the Dielectric folder

b.   In the directory under OptiFDTD_Designer1, under the Profiles folder, right click the Channel folder. A context menu appears. Select New. The Channel Profile dialog box appears.

•  Type the following Profile name: waveguide

•  Under 3D profile definition: Type the following information: Layer name: WG

Width: 1.0

Thickness: 1.0

Offset: 0.0

•  In the Material list, select n=1.5

• Click Add.

•  To save the channel profile, click Store.

Waveguide appears in the Channel folder in the directory,

4Return to Initial Properties Dialog box of Waveguide Layout Designer.

Either minimize or close the Waveguide Profile Designer.

5Type the following information in each corresponding area in Initial Properties Dialog box:

Waveguide Properties:

Width (um): 1.0

Profile: Waveguide

(This profile will be used by default when drawing a waveguide in the layout window)

Wafer Dimension

Length (um):7.0(z-direction dimension)
Width (um):3.0(x-direction dimension)
3D Wafer Properties
Cladding Material:Air
Cladding Thickness:2.0(y-direction dimension)
Substrate Material:Air
Substrate Thickness:1.0(y-direction dimension)

ck OK in Initial Properties Dialog box. OptiFDTD Designer-

6Click OK in Initial Properties Dialog box. OptiFDTD Designer- [OptiFDTDigner1] window appears.

Note:

•     Your shortcut Toolbars may not all appear in the window. You can change it from the “View->Toolbars” menu option.

•     Click “+” (zoom) toolbar button to enlarge the layout window

7Draw a linear waveguide in the layout window.

•     From the Draw menu, select Linear Waveguide. Or select the Linear Waveguide shortcut toolbar.

•     In the layout window, drag the linear waveguide from the start point to the end point. A linear waveguide appears in the layout window.

•     (Change the mouse drawing tool by selecting the arrow shortcut icon on the toolbar)

•     To adjust the position and the shape of the waveguide, in the layout window, double-click the Linear Waveguide. The Linear Waveguide Properties dialog box appears.

•     Click the Start tab and type the following values:

•     Horizontal offset (um):0.0(Start point for z-direction)

Vertical offset (um): 0.0 (Start point for x-direction) Width (um): 1.0 (Waveguide x-direction width) Depth (um): 0.0 (Waveguide y direction bottom) Label: Linear1

Channel Thickness Tapering:Use Default (Channel: None)

(Waveguide y-direction thickness setting)

•     Click the End tab and type the following values: Horizontal offset (um): 7.0

Vertical offset (um): 0.0

Note:

•     You can also set a variable in the expression – click Evaluate to verify the final value of the expression.

•     Horizontal means the z-direction.

•     Vertical means the x-direction.

•     Depth means the y-direction.

•     From the Profile list, select Waveguide.

•     Click OK to finished the waveguide setting

Now, you have defined a simple straight waveguide. For more complex layout, Please refer to other tutorial lessons.

Note:

• To add new materials and waveguide profiles select the Profiles and materials under the Edit menu of OptiFDTD Designer window to start the Profile Designer.

• To change the simulation domain dimension, select Wafer Properties under the Edit menu of OptiFDTD Designer window.

The Input Wave signal is defined within the Input Plane. To insert the Input Plane and
set the excitation wave, follow the steps below:

StepAction
1From the Draw menu, select Vertical Input Plane, or select Vertical Input Plane shortcut toolbar (The Vertical Input Plane is in the x-y plane for 3D.)
2Click in the layout window at the position where you want to insert the Input Plane. A red line that represents the input plane appears in the layout window.
3To set up the Input Plane properties, double-click the red line (Input Plane) in the layout window. The Input Field Properties dialog box appears.
4Set the time domain Input Plane basic information.

a.   Select Gaussian Modulated Continuous Wave.

The Gaussian Modulated CW tab appears.

b.   Wavelength (um): 1.5

Note:

•     Continuous Wave

•     Wavelength is a single wavelength that is used in simulations.

•     Gaussian Modulated Continuous Wave

•     Wavelength is the carrier wavelength (center wavelength) for the pulse simulations.

5Click the Gaussian Modulated CW tab. To set the time domain input waveform. The time domain pulse graphics appear. Type the following values for the time domain input plane

Time offset (sec.): 2.0e-14

Half width (sec.): 0.5e-14

Note:

•     Both the time domain wave and frequency domain wave for the Input Plane appear.

•     The Frequency domain information is obtained by FFT from the time domain series.

•     Right Click on the graph and select the Zoom In tool to enlarge the selected graph region. You can observe the bandwidth in this way.

•     Adjust half width can adjust the bandwidth

6To set up the general information (transverse field distribution) for the Input Plane, click the General tab.

Input Field Transverse: Modal

Z Position (um): 1.5

Plane Geometry: Positive direction

Label: InputPlane1 (default)

Note: Positive Direction means that the Input Plane is excited to the positive z-direction. TF/SF technique is used for the excitation algorithm, which makes sure the wave is excited and propagates only in one direction, and then behind the input wave the pure reflection wave can be detected.

7To solve the 3D transverse mode, click the 3D Transverse tab. Select one waveguide (it is selected by default in this sample) and click Find Mode. ADI Method mode solver dialog box appears. Follow the default setting to solve the mode:

General

Solver: Real

Waveguide: Straight

Mode:

Semi-vector TM, (y-polarization input wave)

Click Calc Mode to start the mode solving. The modal field and the modal index will be shown in the M3DTmp3 window. Clicking this window will save the mode solver setting and come back to input plane dialog box.

Note: Click Data in mode solver M3DTmp3 window to save (export) the results.

8To complete the Input Plane setup, click OK.