| Step | Action |
| 1 | From the Simulation menu, select Simulate 3D Using 64-bit Simulator.
The 3D Simulation Parameters dialog box appears (see Figure 1).3D simulation parameters dialog box |
Figure 1: 3D Simulation parameters dialog box
| 2 | Type the following values for the mesh size:
Mesh Delta X (mm): 0.07 Mesh Delta Y (mm): 0.07 Mesh Delta Z (mm): 0.07 Note: The total mesh number for each orientation will be calculated automatically, once focus is removed from the specific edit region. |
| 3 | To set up the boundary condition parameters, click Advanced. The Boundary Conditions dialog box appears. Type the following values for the boundary condition:
Anisotropic PML layer number: 12 Theoretical Reflection Coefficient: 1.0e-12 Real Anisotropic PML Tensor Parameter: 1.0 Power of grading Polynomial: 3.5 |
| 4 | Run for 900 time steps |
| 5 | Time sampling interval: 5
Note: – Time steps size The default value ensures stability and accuracy of FDTD simulations – Time step number The default value ensures that the wave completes propagation through the whole layout – Time sampling interval This sampling rate applies to observation areas. It determines how many time domain response sample points are used for the spectrum calculation. |
| 6 | Click the “Spectrum” button to set the spectrum range (refer to Figure 2) Set “Number of Samples” to 61,
Uncheck the “Auto” checkbox, Check the “Use Wavelength” radio button Set Start wavelength as 1.35um Set end wavelength as 1.65um and press Ok button to accept changes |
Figure 2: Spectrum DFT simulation parameters
| 7 | Click Ok button to accept the specified simulation parameters |
Observe the Refractive Index
| Step | Action |
| 1 | Click on “3D_Ref_Idx-Re(y)” tab on the bottom of the layout frame or select “Refractive Index” in the View Menu. View of the refractive index distribution slice appears. |
| 2 | Change the slice orientation and move the slice position to observe the index distribution (refer to Figure 3, and Figure 4)
— Select Height Plot shortcut toolbar to observe the refractive index in height plot format. — Right click on OptiFDTD graph to display the available graph tools/menus |
Figure 3: Refractive index in x-z orientation at y=0.5
Figure 4: Refractive index in x-y orientation at z=0
Setup the Observation Objects (result data-detector)
For the 32-Bit FDTD simulation, observation objects will record all the time domain response so that spectrum analysis can be performed in analyzer. For 64-Bit FDTD simulation, Observation points will still record all the time domain response in each single point, but Observation area will perform the spectral analysis in simulator and save the spectrum DFT results to the analyzer file. For 64bit FDTD simulation, Observation Points or Observation Area must be present; otherwise simulations will not store any results for further analysis.
• Observation Point
Observes the time domain and frequency domain response. The transmission function can be obtained from the Observation Point analysis.
• Observation Area
It is used to compute power transmission ratio, and normalized power (power transmission /reflection) versus wavelength.
| Step | Action |
| 1 | From the Draw menu, select Observation Point. ( or select Observation Point shortcut from the toolbar) |
| 2 | Place the Observation Point in the desired position in the layout. |
| 3 | Double-click the observation point. The “Observation Properties – Point” dialog box appears. Type the following values in the dialog box:
General Center Horizontal Offset: 5.2 Center Vertical Offset: 0.0 Center depth: 0.5 Label: ObservationPoint1 Data Components Ex, Ey |
| 4 | Click OK to close the dialog box |
| 5 | Repeat step 1-4 to design another Observation point with the following properties:
General Center Horizontal Offset: 0.7 Center Vertical Offset: 0.0 Center depth: 0.5 Label: ObservationPoint2 Data Components Ex, Ey Note: • The Observation points are placed at the position where the peak value is expected. This will make sure that the response in observation point can be compared with the input wave peak value. • Observation point 1 will detect the transmitted wave while Observation Point 2 will detect the reflected wave. |
| 6 | From the Draw menu, select Observation XY Area ( or select Observation XY Area shortcut from the toolbar) |
| 7 | Place the observation XY area in the desired position in the layout. |
| 8 | Double-click the observation area. The “Observation Properties – XY area” dialog box appears. Type the following values in the dialog box:
General Center Horizontal Offset: 5.5 Center Vertical Offset: 0.0 Center depth: 0.5 X Length: 3.0 Y length: 3.0 Label: ObservationArea1 Data Components Ey, Hx Note: • The time domain response for selected data components will be recorded through the simulation. • Ey and Hx together will determine the y-polarization z-propagation Poynting vector |
| 9 | Click OK to close the Observation area dialog box |
| 10 | Repeat step 6-9 to design an Observation XZ Area with the follow properties:
General Center Horizontal Offset: 3.5 Center Vertical Offset: 0.0 Center depth: 0.5 X Length: 2.0 Z length: 7.0 Label: ObservationArea2 Data Components Ey |
Click Save under File menu to save the designed project. Now your layout should look like the one on Figure 5.
Figure 5: Layout
Perform the 64Bit-FDTD FDTD Simulation
| Step | Action |
| 1 | From the Simulation menu, select the “Simulate 3D using 64-Bit Simulator…” option. The 3D Simulation Parameters dialog box appears. |
| 2 | Click Run to start the simulation. The progress window appears (see Figure 6). It displays status of the simulations. |
Figure 6: FDTD simulation progress window
| 3 | Visualization of intermediate simulation results. First, configure the snapshot settings. Select “Simulation ->Take Snapshot” menu option. The “Set Snapshot” dialog box appears (Figure 7)• Click Browse button to select the location of the output file • Check the observation areas or observation points. The time domain response in the selected observation objects for the current time-step will be save to the file • Click OK to close this dialog box |
Figure 7: Setting Snapshot dialog box
| 4 | Click the “Take Snapshot” button in the simulation progress dialog box to save the time domain response in the current displayed time step |
| 5 | Go to the folder where the snapshot is saved and with 2D or 3D Viewer observe the time domain response for a certain time step (refer to Figure 8) |
Figure 8: The time domain snapshot observed in 3D Viewer from observation area 2
When Simulation is finished, you will be asked if you want to open the analyzer to view the results. Click yes to start the analyzer.