Noncollinear three‐phonon interactions in a multimode structure

摘要

Excitation of Lamb waves in the five lowest‐order modes is demonstrated on polarized plates of PZT by using interdigital transducers. It is shown that in this structure the nonlinear interaction of noncollinear phonons can produce sum‐ and difference‐frequency beams at arbitrary angles. This is accomplished by interacting waves propagating in various combinations of the many available Lamb modes and by selecting frequencies and wave vectors that satisfy energy and momentum conservation. The phenomena described may have applications to acoustic signal processing.