RCWA Simulation Workflow
The RCWA solver, available in FDTD starting with version 2022 R1, was used to run the simulations in the above visualization. The RCWA solver is accessed by using the RCWA script command, and the simulation is set up and executed through the use of a script file.
1. Initial Calculation
The RCWA solver computes transmission and reflection from the photonic crystal slab at normal incidence using typical simulation parameters. Calculations are also made for the electric field values at the slab’s center.
2. Convergence Testing
The number of k-vectors employed by the RCWA solver is swept in a convergence test to ascertain how the transmission peak positions converge to the outcomes from. To see how simulation time varies with the quantity of k-vectors, the duration of each simulation is also tracked.
3. Sweep the Incident Angle
The reflection and transmission from the photonic crystal slab are computed using the RCWA solver at various incident angles.
The geometry is created, the simulation and source properties of the RCWA solver are established, the simulation is run using the rcwa script command, and the results are plotted by the script pc slab rcwa.lsf. The polygon geometry object is used to build a single unit cell of the photonic crystal, which consists of a silicon slab with a single hole in the center. The RCWA solver makes the assumption that the structure is periodic in the directions perpendicular to the source’s injection axis.
- Where c is the speed of light, a represents the period, and f is the frequency.
The script also plots the square magnitude of the electric field at the slab’s zero-point (z = 0) at a frequency of 149.896 THz for the S polarized source.
Geometric Modifications for Lumerical
By changing the geometry objects’ characteristics, the structure of the model can be altered. A more sophisticated model can be made by including more geometric objects. It is crucial to confirm that the layer position property’s dimension makes sense given the altered geometry. The geometric layer positions object needs to be updated if the number of layers has changed.
Modifications to Plane Wave Sources
By altering the excitation struct in the script file, it is possible to change the properties defining the incident plane wave. Changes can be made to the incident light’s frequency range, incidence angle, and polarization. For further details, visit the documentation page for the rcwa script command.
Options Solver Modifications
By altering the options object in the pc slab rcwa.lsf script file, it is possible to modify the solver’s performance in terms of accuracy and simulation time. It is possible to increase the number of k-vectors: max N to obtain a more precise answer. As the maximum number of k-vectors is increased, more simulation time will be needed.