FDTD Band Solver in OptiFDTD is a supplementary tool for the Photonic Crystal
(PhC) and Photonic Band Gap (PBG) structure. Currently it employs the FDTD method and generates what is called the Band Diagram. For the transmission and reflection analysis for PhC and PBG, it is still suggested to use the conventional FDTD method demonstrated in Lesson 3—Photonic crystal and photonic band gap simulation, because the FDTD simulation for generating the band diagram is dependent on the initial condition, Bloch’s periodic boundary condition, and sufficient monitor points. This means that there is no guarantee that all bands will be found. In future releases, we will update the PWE method, which will guarantee that all the necessary bands will be found.
To start the band solving, you need to define a photonic lattice structure in the layout window. If no photonic crystal lattice exists in the layout window, then the FDTD band
solver is not active—the 2D band solver item in the simulation menu is disabled.