Features of Normal Higher-Order Acoustic Wave Generation in Thin Piezoelectric Plates

The article studies the spectrum of acoustic oscillations generated by interdigital transducers in a plate made from a LiNbO3 piezocrystal with a thickness on the order of the acoustic wavelength. It is shown that, along with zeroth and higher-order modes, this spectrum also contains odd harmonics of the same modes. Unlike surface waves without dispersion, the harmonic frequencies of normal waves are not exact multiples of their fundamental frequency due to velocity dispersion, and the harmonic amplitudes can differ from the wave amplitudes at fundamental frequencies due to the dispersion of the electromechanical coupling coefficient. The temperature sensitivities of modes and harmonics differ from each other and vary with the fluid loading of the surface.