Reconfigurable source illusion device for airborne sound using an enclosed adjustable piezoelectric metasurface

Source illusion is an important issue in acoustic fields that has significant applications in various practical scenarios. Recent progress in acoustic metasurfaces has broken the limitation of manipulating large-scale waves at subwavelength scales and enables a better illusion capability, while there is still a problem that most previous studies are hampered by a lack of tuning capability. Here we propose a reconfigurable source illusion device capable of providing azimuthally-dependent phase delay in real-time via changing the static voltage distribution. The resulting device is implemented by employing an adjustable piezoelectric metasurface with a subwavelength thickness that can achieve a full 2π-phase shift while maintaining efficient transmittance. The effectiveness of our mechanism is demonstrated via two distinctive source illusion phenomena of shifting and transforming a simple point source without changing the device geometry. We anticipate that our methodology, which does not require a large device size or a complicated phased array, will open up new avenues for the miniaturization and integration of source illusion devices and may promote their on-chip applications in a variety of fields, such as acoustic camouflage and manipulation precision.