Quantitative study on the nonlinear piezoelectric effect in KNbO₃ single crystals for a highly efficient surface acoustic wave elastic convolver

In this article we describe quantitative studies on the nonlinear piezoelectric effect in KNbO₃ single crystals for a highly efficient surface acoustic wave elastic convolver. First, we demonstrate that a simple measurement of the nonlinear piezoelectric constant of e₃₅₅ is very effective for quantitative estimation of the efficiency of an elastic convolver. Next, the third-order piezoelectric constants, e₃₅₅, e₃₃₃, and e₃₄₄, in rotated Y-cut KNbO₃ substrates are measured by varying the velocity under an applied electric field. Using the third-order piezoelectric constants measured, quantitative estimations of the convolution efficiency are discussed.