Generation mechanisms of second-order non-linearity in surface acoustic wave devices

This paper discusses generation mechanisms of the second-order distortion in SAW devices. Crystal symmetry of the substrate is considered. It is shown that three mechanisms cause the second-order distortion. Namely, (a) self-mixing of the electrostatic field, (b) mixing of the electrostatic field with the strain field of the SAW main mode, and (c) mixing of the electrostatic field with the strain field of the SAW transverse modes. Then the frequency response of the second harmonics generation is discussed by using the coupling-of-mode theory.