Coupled‐amplitude analysis for semiconductive nonlinearities of surface acoustic waves and its application to the second harmonic generation of Bleustein‐Gulyaev waves

摘要

A perturbation formula is developed to provide a systematic way of analyzing the nonlinear interaction of waves in piezoelectric media. From this perturbation formula, a set of coupled‐amplitude equations is obtained for surface acoustic waves coupled with the charge carriers in an adjacent semiconductor. The nonlinear coupling coefficients associated with semiconductive nonlinearities are expressed explicitly in terms of material constants of the piezoelectric substrate and the semiconductor layer, wave vectors, and polarizations of interacting beams. Making use of the coupled‐amplitude equations, the generation of second harmonic Bleustein‐Gulyaev waves is studied. The dependence of the second harmonic signal on the thickness and resistivity of the semiconductor sample is investigated and compared with the experimental results.