Dispersion properties and data analysis of meromorphic nonlinear susceptibility of layered two-phase nanocomposites

The case of layered two-phase nanocomposites has been numerically studied. Contrary to the earlier studies on the subject, material's susceptibilities are allowed to be complex valued and to change as a function of frequency. Thereby, new effects arise, e.g, the phase of the effective third-order susceptibility chi(eff)((3)) of a nanocomposite can have a huge frequency dependent increase near resonances compared to corresponding phase changes of chi((3)) of the constituent materials. Unfortunately, the phase changes cannot be predicted from the amplitude measurement \chi(eff)((3))\ by the Kramers-Kronig methods, because chi(eff)((3)) is, in general, a meromorphic function in a complex frequency plane, and thus, a conventional Kramers-Kronig relation does not exist between the amplitude and phase of chi(eff)((3)). In this paper another type of phase retrieval procedure, based on the maximum entropy model, is shown to be applicable for chi(eff)((3)).