Measurements have been made of the nonlinearly generated harmonics and attenuation of Rayleigh acoustic surface waves at microwave frequencies on crystalline quartz. The Rayleigh waves were generated using an interdigital transducer deposited on thexhyphen;zsurface of the quartz crystal aligned so that the surface wave propagates in the purehyphen;modexdirection. Attenuation coefficients agr; were measured using the laser diffraction technique at frequencies of sim;160, sim;280, and sim;492 MHz with resulting typical values of agr;equals;0.083 dBsol;mgr;sec, agr;equals;0.206 dBsol;mgr;sec, and agr;equals;0.812 dBsol;mgr;sec, respectively. These results agree with previously reported values and with theoretical predictions. The growth and decay of nonlinearly generated harmonics of Rayleigh waves with a fundamental frequency of 281 MHz were observed also using the laser probe technique. A description of the variation of the Rayleigh waves' intensity for each of the three harmonics observed is provided by a set of coupled amplitude equations modified to include dispersion effects. It was not possible to describe the data using the coupled amplitude equations without including terms containing dispersion. Surface imperfections are assumed to be responsible for the dispersion as well as to contribute to the residual values for the attenuation coefficients. The small amount of dispersion needed for a good fit is determined. The nonlinearities are characterized by a set a nonlinear coefficients Ggr;. A computer program was written in order to solve the coupled amplitude equations and to determine a set of Ggr; values which provide a best description of the experimental data.
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