Possibility of Switching and Steering Surface Waves by Nonlinear Mixing in Anisotropic Media

Abstract

It is known that when two acoustic surface‐wave beams intersect in a suitably anisotropic medium, sum and difference frequency beams are generated parametrically if both frequency and phase velocity are matched. Using coupled‐mode theory we show that this effect can occur even in the presence of imperfect phase matching. In consequence it should be possible to produce sum and/or difference frequency beams over a continuous range of angles, with the direction controlled by the ratio of the input beam frequencies. Computed input and output beam angles are presented for a number of materials and device applications are discussed.