Visualization of nonlinear SAW displacements in resonators induced by nonlinear elasticity

The nonlinear elastic model for surface acoustic wave (SAW) duplexers we have proposed last year precisely simulates the frequency responses of the in-band 3rd order nonlinear distortion, `triple beat'. This result suggests that the main cause of the triple beat is the nonlinear elasticity of SAW. If this hypothesis is correct, the nonlinear SAW displacements should be induced in resonators by the nonlinear elasticity during the triple beat tests. In this paper, the optical interferometer detects and visualizes the nonlinear SAW displacements for the first time, which have the almost same amplitude and distribution as those predicted by the model. This result proves that the nonlinear elasticity produces the triple beat responses in SAW duplexers.