Effective media equivalent to an asymmetric multilayer and to a rough interface.

A computer fitting program is used to show that not only a symmetric but also an asymmetric multilayer, composed of a periodic structure with small thickness irregularity or with slightly rough interfaces, can be equivalent to an anisotropic single layer within a good approximation. It is also shown that an interface layer equivalent to a rough interface does not exist, in spite of the fact that such an assumption has widely been used.