Finite Element Analysis of the Third-Order Harmonic nonlinearity and its Generation Mechanism in SAW Resonators

This work systematically investigates the third-order harmonic nonlinearity of surface acoustic wave (SAW) resonators by integrating the finite element method (FEM) with perturbation theory. First, the third-harmonic (H3) nonlinear signals in 42°YX–LiTaO3based SAW resonator was simulated using a nonlinear FEM model. This model was validated by comparison of the simulated H3 to that of the experimental results. The simulated and measured results exhibit excellent agreement in both amplitude and phase of H3, demonstrating the capability of phase analysis. Furthermore, contributions of the six independent strain components to the H3 response were individually calculated and analyzed, showing that the Syz component dominates both the amplitude and phase responses in the overall H3 behavior. This work provides valuable insights for the design of high-performance SAW devices in radio-frequency front-end circuits and potential applications for nonlinear suppression through phase-based optimization.