Large-angle acoustic-beam steering in acoustically anisotropic crystal

Abstract

We have demonstrated a unique scheme for electronically steering an acoustic beam over an angle large than 70°in a TeO2 crystal. The idea is based on the principle that the acoustic energy flow direction is always normal to the slowness curve in an acoustically anisotropic crystal. In the plane normal to the c axis of a TeO2 crystal and around the (110) axis, the shear wave acoustical energy flow directions can have a swing of more than 70°[from the (110) axis] by changing the wave-vector direction only 3°from the (110) axis. Using a grating to diffract a shear wave propagation direction around the (110) axis, we have observed the wide-angle acoustic-beam steering effect by a laser probe.