Bidirectional asymmetric acoustic focusing with two flat acoustic metasurfaces*

Project supported by the National Natural Science Foundation of China (Grant Nos. 11704193, 11674175, and 11704192), the “333” Project of Jiangsu Province, China (Grant No. BRA2017451), and the Postgraduate Research & Practice Innovation Program of Jiangsu Province, China (Grant No. KYCX18_1185).

Chen Di-Chao, Zhu Xing-Feng, Wei Qi, Wu Da-Jian
       

(color online) (a) Arrangement of AM with 80 subunits. (b) Schematics of three-layered acoustic space-coiling (TAS) subunit. (c) Transmitted phase shifts (dashed line for left-hand scale) and amplitudes (solid line for right-hand scale) of TAS subunit as a function of t.