What are some of the implications for existing code that's been incorporating complex materials (and thus complex wavevectors)?
Prior to this fix, complex permittivity would sometimes have yielded an in-plane wavevector corresponding to a wave propagating in an incorrect direction, e.g. -theta when +theta is desired. It also could have led to the modes which carry power forwards being treated as backward-going, and vice versa.
Note that this issue only arises for non-normal incidence.
Prior to this fix, complex permittivity would sometimes have yielded an in-plane wavevector corresponding to a wave propagating in an incorrect direction, e.g.
-thetawhen+thetais desired. It also could have led to the modes which carry power forwards being treated as backward-going, and vice versa.Note that this issue only arises for non-normal incidence.