Ansys Insight: How can the background material be changed in FDTD and MODE?
By default, the background material in FDTD and MODE simulations is vacuum, with a constant refractive index of 1. This is the refractive index used in the simulation for regions where there is no geometry object.
In the FDTD, FDE, varFDTD and EME solvers, this can be changed with the "background material" setting of the solver objects. This setting is found under the "General" tab of the solver object's edit dialog. For example, in FDTD:
Any material from the Material Database that can be used for a 3D object can be chosen for the background material. If the "<Object defined dielectric>" material is chosen, a constant real refractive index can be used for the background. This constant refractive index value can be set with the "index" setting, below the "background material" field in the screenshot above.