Solitary waves in nonlinear phononic crystals

Abstract

[EN] We discuss two possible regimes of solitary wave formation in acoustic layered media. In the weakly dispersive limit, KdV-type solitons are formed, consisting of broad pulses with a width much larger than the lattice periodicity. Such KdV solitons are shown to exist even far from the weakly dispersive conditions. On the other hand, in the strongly dispersive regime, gap acoustic solitons are demonstrated. They are formed by a fast carrier wave inside the band-gap of the structure, near the Bragg frequency (whose propagation is not allowed in the case of linear waves), modulated by a wide envelope, whose width lies inside the gap. Gap solitons propagate slower than linear waves, or can be even reach a stationary non-propagating state within the medium. The parameters for a realistic acoustic medium supporting both types of solitary waves are discussed