SELF-MODULATED NONLINEAR SURFACE SHEAR ACOUSTIC-WAVES IN CRYSTALS

Nonlinear pure shear surface acoustic waves (SAW) occuring in crystals are studied. The set of SAWs described by the N-soliton solutions of the nonlinear Schrodinger equation is derived. The simplest of them was earlier obtained by Mozhaev [13]. The higher-order waves possess self-modulation along the propagation at the spatial frequency proportional to U0(2)(U0 is the maximum amplitude at the crystal surface); the amplitude may nonmonotonically decrease with depth. The characteristic localization length for such SAW is proportional to U0(-1). The excitation of waves of each order with the help of cophasal oscillations localized at the crystal surface may be of a threshold character. The wave stability against small changes in the boundary conditions and against the depth-dependent random perturbation of the oscillation phase in the initial cross-section is examined.