The core strength of FDTD lies in the . Instead of calculating Electric ($E$) and Magnetic ($H$) fields at the same point, the algorithm staggers them spatially and temporally.
: Simulates quantum dots or fluorescent molecules.
To prevent numerical simulation divergence, the time step ( Δtdelta t
This comprehensive tutorial covers everything you need to build, run, and analyze your first photonic simulation. 1. Understanding the FDTD Method
Results can be exported in multiple formats for external analysis: lumerical fdtd tutorial
Through step-by-step exercises, the tutorial demonstrates how setting the mesh size ($\Delta x$) relative to the wavelength ($\lambda$) directly impacts accuracy. A key takeaway is the rule of thumb that a mesh of $\lambda/(10-20)$ is required for qualitative results, while plasmonic or high-index contrast structures demand far finer resolution. This reinforces the concept that FDTD is not an automatic solver but a tool requiring deliberate numerical parameterization.
Click the dropdown and select Mode . A mode source injects the precise physical waveguide mode profile. Edit the Mode Source: General: Set Injection Axis to X-Axis (Forward direction).
spans to cover the region. Set material to SiO2 (Glass) - Palik .
Absorbs outgoing light completely, simulating open space. Use this for boundaries where light escapes. The core strength of FDTD lies in the
switchtolayout; widths = [0.4e-6, 0.45e-6, 0.5e-6, 0.55e-6]; for(i=1:length(widths)) switchtolayout; setnamed("waveguide", "y span", widths(i)); run; T = getresult("monitor", "T"); matlabsave("sweep_width_" + num2str(widths(i)*1e9) + "nm.mat", T); Use code with caution.
Let's build a classic silicon-on-insulator (SOI) straight waveguide operating at the telecom wavelength of
Manual clicking limits your productivity. Lumerical's built-in scripting interface (LSF) allows you to automate workflows, sweep parameters, and export clean data. Useful Script Snippets
She launched Lumerical FDTD for the umpteenth time. The project file opened, familiar and patient: a world of meshes, monitors, sources, and boundary conditions waiting for decisions. Mira set up the geometry—the same triangular lattice of air holes in silicon she’d modeled since graduate school—and placed the defect: a single enlarged hole, tiny as a thought, at the lattice center. She remembered the tutorial she’d once followed when everything had been a little less mysterious: a step-by-step path that taught her to place sources, add perfectly matched layers, set monitors, and run sweeps. The tutorial had been a map; now she had to improvise. To prevent numerical simulation divergence, the time step
Correct boundary conditions are critical for accurate results:
The FDTD method discretizes space using a Yee grid, where electric and magnetic field components are staggered in both space and time. The quality of your simulation results depends critically on appropriate mesh resolution. The mesh step size must be sufficiently small to resolve the smallest geometric features and electromagnetic wavelengths in your simulation.
Lumerical FDTD Solutions is a powerful tool for simulating and analyzing optical systems using the FDTD method. By following this guide, you'll be able to get started with Lumerical FDTD and simulate a wide range of optical systems. Happy simulating!
A plot window opens displaying the transmission spectrum. For a straight waveguide without defects, the value should hover close to 1.0 (100% transmission across the C-band).