In this tutorial, we have provided a comprehensive guide to using Lumerical FDTD for simulating and analyzing optical systems. We have covered the basics of the software, setting up simulations, and interpreting results. Lumerical FDTD is a powerful tool for designing and optimizing photonic devices and structures, and its applications are diverse and widespread. With this tutorial, users should be able to get started with Lumerical FDTD and begin simulating their own optical systems.
Lumerical FDTD is a commercial software package developed by Lumerical Solutions, Inc. The software is widely used in the field of photonics and optics for designing and simulating various devices, such as optical fibers, waveguides, photonic crystals, and solar cells. Lumerical FDTD provides a user-friendly interface for setting up and running FDTD simulations, allowing users to model complex optical systems and analyze their behavior.
Ansys Lumerical FDTD is the gold standard for modeling sub-wavelength optical devices. By solving Maxwell’s equations in the time domain, it helps engineers design silicon photonics, metasurfaces, and solar cells. This comprehensive tutorial will guide you from the basic interface setup to running your first accurate simulation. 1. Understanding the FDTD Method
Before engaging with the software interface, one must understand its engine. The FDTD method, pioneered by Kane Yee in 1966, discretizes both space and time. It solves Maxwell’s curl equations on a staggered grid—known as the Yee cell—where electric and magnetic field components are offset in space and time. This leapfrog formulation allows the solver to propagate a field forward in time steps, calculating the future electromagnetic field at every point in the simulation volume based on its current and past values. The primary output is the time-evolution of the fields, which can be Fourier-transformed to yield frequency-domain results like transmission, reflection, and field profiles. Lumerical FDTD automates this complex numerical process, offering a user-friendly interface while exposing the key parameters that control accuracy and stability.
Click the button. The software switches from Layout Mode to Analysis Mode . A log window will track the time-stepping fields. The simulation completes when the internal fields decay below the auto-shutoff threshold (default is 10-510 to the negative 5 power lumerical fdtd tutorial
Use a frequency monitor behind the unit cell to extract the phase angle unwrap(angle(E)) of the transmitted field. 5. Automation Using Lumerical Scripting Language (LSF)
Before launching the software, it is vital to understand how FDTD processes your designs.
: Inject light using sources like Plane Waves, Total-Field Scattered-Field (TFSF), or Mode sources.
The tutorial systematically covers source types: total-field/scattered-field (TFSF) sources for scattering problems, mode sources for waveguide injection, and dipole sources for spontaneous emission studies. For each, it explains how to set the pulse width to balance frequency resolution with simulation time, directly tying the user’s actions to the Fourier transform limits. In this tutorial, we have provided a comprehensive
Set Monitor Type to 2D X-Normal . Position it near the end of the waveguide at X = 1.5 µm. Match the Y and Z spans to the Mode Source. Add a second Frequency-Domain Field and Power monitor. Name: Profile
Lumerical provides a comprehensive material database (e.g., Si, SiO₂, Au, Ag) with wavelength-dependent refractive indices (n, k). Users can also define custom materials using models like Lorentz or Drude for dispersive media. The photonic crystal slab—a layer of silicon with a periodic array of air holes—is constructed using primitive geometric objects (rectangles, cylinders) from the layout editor. Boolean operations and parameter sweeps allow for complex, parameterized designs.
Add a . Set plane to YZ, position at (near the exit boundary).
: Best for injecting light into guided structures like silicon waveguides or optical fibers. With this tutorial, users should be able to
Before running, use the feature to ensure no materials are overlapping wrongly and the source is correctly positioned. 6. Scripting and Automation (Lumerical Script Language)
Before drawing shapes, you must define what those shapes are made of. Open the .
Use (Perfecting Matching Layer) to absorb outgoing waves (simulating open space).