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

摘要

Abstract: 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 $VBAR$chi$- eff$/$+(3)$/$VBAR by the Kramers-Kronig methods, because $chi$-eff$/$+(3)$/ is, in general, a meromorphic function in a complex frequency plane, and thus, 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)$/. !6