Novel phononic-crystal-arrayed acoustic metalens for long beam focusing in multi-band

We propose a multi-band acoustic metalens that achieves 18-26 & lambda; long beam focusing and with narrow FWHM of 4-5 & lambda; across multiple frequency bands, utilizing principles of multiple scattering theory. The metalens sample was meticulously fabricated using quadrilateral lattice scatterers in the cross section, and its experimental acoustic field tests showed focused sound beams with a length of 0.78-1.07 m falling within the frequency bands of 5800-6100 Hz, 8500-8700 Hz, and 9700-9900 Hz. This study holds potential applications in acoustic directional projection, signal enhancement, and acoustic power collection.