Periodic Boundary Condition for PBG Simulation


OptiFDTD has options to use simplified Periodic Boundary Condition (PBC). It can work with other boundary conditions such as Anisotropic PML, PMC, and PEC. With PBC, you can simulate a simple plane wave simulation, or a periodic layout simulation.

For more information regarding PBC, see the Technical Background.

The following procedure is based on . You can also open the project file Sample09_2D_TE_PBG_Domain_Reduced_Square_Lattice.FDT that can be found in the Sample file folder.

Setting the 2D TE FDTD simulation parameters

Step Action
1 From the Simulation menu, select 2D Simulation Parameters.

The Simulation Parameters dialog box appears.

2 Type/select the following information:

Polarization: TE

Mesh Delta X [μm]: 0.05

Mesh Delta Y [μm]: 0.05

3 Click Advanced….

The Boundary Conditions dialog box appears.

4 Type/select the following information (see Figure 107):



-Z: Anisotropic PML

+Z: Anisotropic PML

Anisotropic PML Calculation Parameters

Number of Anisotropic PML Layers: 10

Theoretical Reflection Coefficient: 1.0e-12

Real Anisotropic PML Tensor Parameters: 5.0

Power of Grading Polynomial: 3.5

FDTD - Figure 107 2D simulation parameters

Figure 107: 2D simulation parameters

Note: The rectangular beam with PMC boundaries on the edge realizes the TE plane wave simulation for the periodic structure.
5 In Time Parameters, click Calculate.

The default time step size is calculated.

6 Select Run for 12000 Time Steps (Results Finalized).
7 Select Key Input Information: Input Plane1 and wavelength:1.9.

Note: The input plane’s center wavelength is used for DFT calculations.

8 Click OK to close the Simulation Parameters dialog box without running the simulation, or click Run to start the OptiFDTD Simulator.

Note: Before running the simulation, save the project to a file.

9 Perform the simulation and Post-processing analysis as shown in. You will get the same result as shown in Figure 104.