Non linear mixing of surface acoustic wave collinear beams

Nonlinear interaction of collinear surface acoustic waves of different frequency generates wave beams at the sum and difference frequencies. The produced fields are here analyzed through the use of a theoretical model that considers the nonlinearly generated field at any given point to be obtained by the sum of all the possible contributions deriving from the interactions between the different plane wave components of the fundamental wave Fourier spectrum. Theoretical and experimental transversal profiles of the nonlinear field at sum and difference frequencies are given for surface acoustic waves propagating on a yz-LiNbO sample. The funda- mental waves were emitted by two equally wide interdi- gital transducers with central frequencies f =60MHz, f =40MHz, respectively.