Acoustic focusing by a double layered acoustic grating

•A double layered acoustic grating is proposed for acoustic focusing with high energy transmission efficiency.•Surface coupling approach is employed to predict the wave propagation manipulated by the double layered acoustic grating.•The geometrical size of the double layered acoustic grating is optimized to converge the acoustic energy of an incident plan wave in a predefined focusing region.•Acoustic focusing is experimentally validated using 3D printed double layered acoustic gratings.