Elastic Phased Diffraction Gratings for Manipulation of Ultrasonic Guided Waves in Solids

Lamb waves and surface acoustic waves (SAWs) are of great interest for frontier technologies, including structural health monitoring, energy harvesting, sensors, and acoustic tweezers. This work presents elastic phased diffraction gratings, passive structures for controlling guided ultrasonic waves in solids. Such a grating adopts an array of interchangeable superstrates to modulate wave dispersion, and thus the diffraction wave field. Experiments demonstrate the ability to modulate antisymmetric and symmetric Lamb waves at 100 kHz, and Rayleigh SAWs at 100 MHz. These gratings are comparatively easy to fabricate, interchangeable, and theoretically feasible for all Rayleigh-Lamb modes.