Fig. 3: A metasurface-based Schroeder diffuser.

a | A schematic of a 2D Schroeder diffuser (SD), including an inset (bottom) showing the cross section of the unit cells. b | A schematic of the proposed metasurface-based SD (MSD), including an inset (bottom) showing the cross section of a unit cell. c | The analytical and simulated relationship between the phase shift and the geometric parameter w at the centre (6,860 Hz) of the working frequency band. d | Simulated and measured diffusion coefficient (d_n) values for normal incidence (left) and 45° incidence (right) in the x–z plane versus frequency (f) for the broadband MSD (BMSD) and the conventional SD, respectively. λ, wavelength; D, width of a unit cell; w, neck width of the cavity. Adapted with permission from ref.⁸, APS.