3E-1 Fast Numerical Technique for Simulation of SAW Dispersion in Periodic Gratings and its Application to Some SAW Materials

A method for approximation of harmonic admittance of an infinite periodic grating, which takes into account interaction between SAW (or LSAW) and BAW, is presented. A numerical technique based on this method is non-iterative, fast and accurate and enables extraction of dispersion parameters from numerical admittance calculated at real-valued spectral frequencies. Excellent agreement with admittance can be obtained in a wide range of temporal and spectral frequencies, including the interval where there is a strong interaction between SAW and BAW. Application of the method to different types of surface waves - Rayleigh-type SAW in LiNbO₃, SH-type leaky waves in LiTaO₃ and high-velocity LH-type leaky wave in Li₂B₄O₇, is demonstrated. The extracted dispersion curves are in a good agreement with the dispersion found by the search of poles in complex spectral domain.