What is The Difference Between Periodic and Bloch Boundaries?

Date	Category
2023-12-06 21:43:10	Boundary Conditions

Periodic and Bloch boundary conditions are very useful for simulating periodic structures. When using Periodic boundary conditions, the fields are registered on one edge of the simulation domain and re-injected at the opposite edge. Bloch boundary conditions are similar, but they also apply a phase correction term to the fields. In other words, Periodic boundary conditions can be considered a special case of Bloch boundaries. When a normal incident plane wave is considered, there will not be any difference between them. However, if we consider a plane wave propagating at an angle, the fields from one period to the next will not be exactly periodic and will be out of phase by some amount. The Bloch boundary condition corrects this factor. Therefore, when injecting plane waves at an angle, Bloch boundaries should be used.