Multiple focused-waves production by parametric mixing in a layer with hysteretic quadratic nonlinearity

Ultrasonics. 2002 May;40(1-8):697-702. doi: 10.1016/s0041-624x(02)00238-x.

Abstract

Nonlinear scattering of a weak probe wave by a strong pump wave in a layer with nonlinearity hysteresis is analysed. It is demonstrated that a spherical probe wave from a point source after nonlinear process of difference frequency excitation is scattered in several foci. Different foci correspond to different frequencies of the transformed wave spectrum. In the case of a plane pump wave and under the condition that nonlinear scattering proceeds without acoustic mode conversion wave front reversal is possible. To achieve wave front reversal in a layer with hysteretic quadratic nonlinearity the pump wave should have a frequency equal to the frequency of the probe wave or to any of its subharmonics.