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

Caroline Pouya,Geoff R Nash

doi:10.1038/s43246-021-00163-w

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.

Highlights

Surface acoustic wave (SAW) devices are used in a wide range of applications including sensing and microfluidics, and are being developed for applications such as quantum computing
In this work we demonstrate, through both modelling and experiments, the presence of slow and fast SAWs within an array of square annular hole resonators, and show that the phase velocity within the array can be controlled via frequency selection
The reduction or increase in phase velocity originates from the modes to which the SAW can couple at a particular frequency and the displacements induced by local resonators within the array

Summary

Introduction

Surface acoustic wave (SAW) devices are used in a wide range of applications including sensing and microfluidics, and are being developed for applications such as quantum computing. 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 be applied to other elastic waves. The ability to engineer and control the type of SAW excited in a device, and the characteristic motion and SAW velocity, is highly attractive as it has the potential to allow new devices to be realized with improved performance or functionality and has been the subject of research for the last half century. The band structure created by a phononic crystal allows the SAW group and phase velocity to be altered compared to that within the unpatterned material[23]

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Conclusion