An optimization approach to the design of weakly reflecting slabs for obliquely incident transient electromagnetic waves

An optimization approach is used in the design of weakly reflecting plane-stratified slabs where transient plane waves impinges obliquely. The slabs are dispersive with a spatially varying impedance and conductivity. In the optimization process, the direct problem is solved iteratively by a time-domain Green functions technique which deals with scattering kernels. Given the prescribed reflection and transmission kernels, an objective functional is minimized for a time larger than one roundtrip and for given incident directions. By introducing dual functions, the exact and explicit expressions for the gradients are derived for the TE and TM modes.