tidy3d.FixedAngleSpec

class FixedAngleSpec

Bases: AbstractAngularSpec

Plane wave is injected such that its propagation direction is frequency independent.

Notes

This spec has different physical implementations depending on the source type:

• On a PlaneWave, Periodic boundary conditions must be used in the transverse directions. Suited to infinite plane-wave illumination of a periodic structure where the user wants the angle held fixed across the source spectrum.

• On a TFSF, the spec injects a frequency-independent oblique plane-wave incidence into an isolated scatterer; BlochBoundary and Periodic transverse boundaries are not allowed. Combining a fixed-angle PlaneWave and a fixed-angle TFSF in the same simulation is also not allowed.

  Note

  Fixed-angle TFSF may be more sensitive than other source types to dispersive media in the layered background that extend into the transverse PML boundaries. If the field decay is not reached in such a setup, switching the transverse boundaries to Absorber is preferred.