Acoustic Metasurface for Space‐time Reflection Manipulation

Abstract Recently, space‐time modulation has revolutionized the wave engineering technologies, providing unprecedented opportunities beyond traditional static systems. This advancement is crucial across diverse fields, ranging from non‐reciprocal transmission to wireless communication. However, the current approaches to sound modulation require bulky artificial structures and are limited in achieving space‐time‐variable sound‐matter interactions. Here, a prototype of space‐time acoustic metasurface (STAM) is proposed and implemented, consisting of a reflective piezoelectric array controlled by a field‐programmable gate array. Leveraging the spatiotemporally programmable phases of the STAM, this is experimentally achieved Doppler‐like chirp modulation and space‐time modulation with deterministic frequency and momentum shifts of waterborne acoustic waves. Furthermore, based on this flexible and efficient modulation strategy, a stochastic space‐time modulation method is introduced, showcasing its applications in single‐channel direction‐of‐arrival estimation. The proposed STAM extends the frontier of wave control and thereby lays the foundation for versatile space‐time applications involving sound.