Multifunctional Waterborne Acoustic Metagratings: From Extraordinary Transmission to Total and Abnormal Reflection

Abstract

Wavelength-thick multifunctional metagratings for waterborne sound are highly desirable in various application scenarios, such as human health monitoring and ocean exploration. In this article, we present a class of metagratings with which distinct and switchable wave manipulation functionalities, such as extraordinary transmission, total reflection, and abnormal reflection can be achieved through a single acoustic grating. Simultaneous and high-efficiency control over both reflected and transmitted waves is achieved through a systematic design approach in which wave diffraction theory, effective medium theory, and intelligent optimization algorithms are concurrently utilized. Switching between different functionalities can be achieved simply by changing the operation frequency, or by changing the incident angles. Robust and perfect wave-front manipulation effects are obtained over a wide range of incident angles and operation frequencies. Our work not only provides a design paradigm of planar acoustic devices for multiple manipulation purposes, but also presents a feasible solution for the development of integrated acoustic devices for distinct underwater applications.