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

We present elastic phased diffraction gratings for passive manipulation of ultrasonic guided waves in solids by engineering the guided wave dispersion and diffraction wavefields. Such gratings are easy to fabricate, interchangeable, and feasible for a wide range of ultrasonic guided modes. We selectively prove the capability for modulating the commonly used antisymmetric A(0), symmetric S-0, and surface Rayleigh modes. Multiple functions including steering plane waves, as well as generating and steering focused, tweezerlike, and bottle-shaped guided wave beams are experimentally demonstrated simply by redesigning and changing the grating's superstrates. Our grating provides an alternative paradigm for manipulating multimodal ultrasonic guided waves in solids and will significantly advance a broad range of applications, such as nondestructive evaluation, structural health monitoring, energy harvesting, and acoustic tweezers.