Acoustic metasurfaces can reshape a reflected wavefront rather arbitrarily, despite being much thinner than the wavelength, thus allowing on-demand wavefront modulation in a variety of applications.Recent passive metasurfaces, however, have suffered from bandwidth limitations, thus restricting their range of operation.In this work, we propose the systematic design of ultra-broadband passive metasurfaces by combining the broadband local reflection rule with an lock shock and barrel art optimization method.The validation of the technique is demonstrated by fabrication and measurement of an ultra-broadband carpet cloak.Numerical and experimental results show that the relative bandwidth of the optimized carpet cloak, thinner than one fifth of the click here maximum wavelength, can exceed 93.
33%, a value that is much larger than that of previous passive metasurfaces.Furthermore, multi-frequency pulse incidence tests reveal the excellent time-domain broadband characteristics of the metasurface over a wide range of angles of incidence.The proposed strategy opens a new route for the design of advanced passive metasurfaces for ultra-broadband wave manipulation and thus promotes practical applications of broadband acoustical devices.