Bessel Acoustic Beams in Transversely Anisotropic Tetragonal Crystals

The influence is investigated of transverse anisotropy on phase velocity and polarization state of plane acoustic waves in 4/m class crystals. For further analysis of the influence of anisotropy on Bessel acoustic beams (BAB) the model of BAB is used as a coherent superposition of plane waves with wave vectors lying on the conical surface. This allows studying a number of BAB features using relatively simple solutions of the Christoffel equations for plane waves. It is shown that destructive influence of anisotropy always increases with the growth in cone angle and most strongly affects BAB formed from quasi-transverse plane waves. At the same time the influence of anisotropy on BAB formed from plane waves with quasi-longitudinal polarization is much weaker. The calculations are conducted of polarization state of three BABs and their spatial structure.