New perspectives for active acoustic metamaterials

Abstract

It is generally accepted that active acoustic metamaterials could, in principle, control impinging sound in ways not possible with passive media. One way to realize this potential is to employ structures composed of sensor-driver unit cells. In this approach, sensors are detecting the impinging wave and actuators are driven coherently with the sensed fields in order to generate almost arbitrary and programmable scattering profiles for the cells. This presentation will briefly review some of the rich and unusual dynamics of metamaterials based on these cells and, most importantly, will highlight the untapped potential of this architecture. In particular, the sensor-driver cells are not limited to generating a response in the same physical field as the excitation. Here, I will focus on metasurfaces that respond with light to acoustic waves. One possible application of these acousto-optical metamaterials will be discussed, namely, the realization of new acoustic imaging devices with potentially much larger resolutions than traditional imaging devices. [Work supported by the National Science Foundation under Grant No. CMMI-1942901.]