FDTD 101: Dielectric constant assignment on Yee grids
Lecture 9: Dielectric constant assignment on Yee grids
In this lecture, we discuss another important source of error that arises from the imperfect description of the dielectric constant distribution of a photonic device on discrete Yee grids. We highlight some subtleties in the dielectric constant assignment on the grids that can lead to significant error. This motivates us to consider more advanced FDTD techniques such as subpixel averaging and nonuniform grid sizes.
- Explain Yee grid in 1D, and show how the dielectric constant is assigned to each grid.
- Take the simulation of the slab transmission spectrum as an example, we show how to count the number of grids assigned to the slab. Then we show that with a basic FDTD algorithm, the slab thickness in the simulation can deviate a lot from the actual slab thickness, resulting in a significant shift of the transmission peak frequency.