Input Plane


To insert the Input Plane and set the excitation, perform the following procedures.

Inserting the Input Plane

Step Action
1 From the Draw menu, select Vertical Input Plane.


–    The Vertical Input Plane is in the x-y plane for 3D.

–    The Horizontal Input Plane is only functional with a 2D simulation.

–    Multiple Input Planes are only allowed in a 2D simulation.

2 Click in the layout window at the position where you want to insert the Input Plane.
A red line that presents the input plane appears in the layout window.

FDTD - Figure 19 Input Plane

Figure 19: Input Plane

3 To set up the Input Plane properties, double-click the red line (Input Plane) in the layout window.

The Input Field Properties dialog box appears.

FDTD - Figure 20 Input Field Properties dialog box

Figure 20: Input Field Properties dialog box

4 Set the time domain Input Plane information.

a.   Select Gaussian Modulated Continuous Wave.

The Gaussian Modulated CW tab appears.

b.   Wavelength (µm): 1.4


–    For Continuous Wave, Wavelength is the single wavelength to be simulated.

–    For Gaussian Modulated Continuous Wave, Wavelength is the carrier

wavelength (center wavelength) for the pulse.

5 Click the Gaussian Modulated CW tab.

The time domain pulse graphics appear.


Type the following values for the time domain input plane.

Time offset (sec.): 4.5e-14

Half width (sec.): 1.2e-14

FDTD - Figure 21 Gaussian Modulated CW tab

Figure 21: Gaussian Modulated CW tab


–    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 clicking on the graph allows you to select the graph tools.

–    Time offset controls the time domain beam center.

–    Half width controls the beam size and bandwidth.

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

a.   Input Field Transverse: Modal

b.   Z Position (µm): 0.63

c.   Plane Geometry: Positive direction

d.   Label: InputPlane1 (default)

FDTD - Figure 22 General tab

Figure 22: General tab

Note: Positive Direction means the that the Input Plane is excited to the

positive z-direction. Negative Direction means that the Input Plane is excited

to the negative z-direction.

8 To solve the 3D transverse mode, click the 3D Transverse tab.

FDTD - Figure 23 3D Transverse tab

Figure 23: 3D Transverse tab

9 Type the following Input Amplitude value (V/m): 1.0
10 Click Find Modes.

The Waveguide selection window appears.

FDTD - Figure 24 Waveguide selection dialog box

Figure 24: Waveguide selection dialog box

11 Select the Linear Waveguide check box, select ADI-BPM Method.

12 To open the mode solver, click Calculate Mode.

The Globe Data: ADI Method dialog box appears.

FDTD - Figure 25 Global Data: ADI Method dialog box

Figure 25: Global Data: ADI Method dialog box

13 Set the following:

Solver: Complex

Waveguide: Straight

Mode (initial excitation): Full Vector, Along Y

Wavelength (µm): 1.4 (the same as the input wavelength by default,


Number of Modes: 1

14 Click the Settings tab and set Boundary Condition: TBC

15 To solve the mode, click Calc. Mode.

The 3D Mode Solver opens.

FDTD - Figure 26 3D Mode Solver

Figure 26: 3D Mode Solver


–    The 3D Mode Solver can take a while to start up.

–    It can take several minutes to solve the mode.

–    A message appears to advise you if no mode has been found.

16 After solving the mode, click the field (Ex, Ey) tab to view the field pattern.

FDTD - Figure 27 Major component Ey tab

Figure 27: Major component Ey tab

17 To return to the Input Field Properties dialog box, close the 3D Mode Solver.

18 To complete the Input Plane setup, click OK.

Saving the layout

To save the layout you have created, perform the following procedure.

Note: Do not save your project over the sample file provided.

Step Action
1 From the File menu, select Save As.

The SaveAs dialog box appears.

2 In the sample folder, enter the name of the file and click Save.

The new sample file is saved in the sample folder.

FDTD - save as

Note: .fdt is the file extension generated by OptiFDTD_Designer.