Localization of nonlinear waves in layered media

The localization of nonlinear waves propagating in an anharmonic medium alo ng a system of two identical plane-parallel defects (waveguides) is investi gated in a simple model describing the nonlinear dynamics of layered media (magnetically ordered, elastic, and optical). A method of analytical invest igation of this problem is proposed which reduces to a model of coupled anh armonic oscillators whose parameters are all determined on microscopic cons iderations. The results yield an adequate description of the nonlinear dyna mics of layered media in the framework of well-studied discrete models of n onlinear mechanics. It is shown that when the total energy of the wave exce eds a threshold value, the state with equal energy fluxes localized near th e waveguides becomes unstable, and an inhomogeneous regime is realized in w hich the wave flux propagates mainly along one of the plane layers. (C) 200 0 American Institute of Physics. [S1063-777X(00)00808-2].