Tunable Beam Splitter Based on Acoustic Binary Metagrating

Abstract

As an inversely designed artificial surface, acoustic metasurfaces usually consist of subwavelength unit cells in an array configuration, exhibiting exceptional abilities in acoustic wave manipulation. In contrast to metasurfaces with subwavelength units and complex configurations, we propose here a comprehensive concept of a beam splitter based on an acoustic binary metagrating (ABM), capable of splitting a given acoustic wave into two predesigned directions. The ABM is composed of only two kinds of elements, corresponding to the elements “0” and “1”, respectively. The diffraction orders in the ABM take a value of n = −1 (split beam 1) and n = 1 (split beam 2), and hence, the beam splitting occurs. We exemplify the ABM by etching only one straight-walled groove per period on a planar hard surface. In our design, the reflected angles of these two split beams can be readily controlled by setting a proper incident angle. Theoretical analysis and numerical simulations were undertaken to provide the proof of concept for the proposed acoustic beam splitter.