Sub- and supersonic elastic waves in an annular hole phononic metamaterial

Abstract

Surface acoustic wave (SAW) devices are used in a wide range of applications including sensing and microfluidics, and are now being developed for applications such as quantum computing. As with photonics, and other electromagnetic radiation, metamaterials offer an exciting route to control and manipulate SAW propagation, which could lead to new device concepts and paradigms. In this work we demonstrate that a phononic metamaterial comprising an array of annular hole resonators can be used to realise frequency control of SAW velocity. We show, using simulations and experiment, that metamaterial patterning on a lithium niobate substrate allows control of SAW phase velocities to values slower and faster than the velocity in an unpatterned substrate; namely, to ~85% and ~130% of the unpatterned SAW velocity, respectively. This approach could lead to novel designs for SAW devices, such as delay lines and chirp filters, but could also be applied to other elastic waves.