Reconfigurable dynamic acoustic holography with acoustically transparent and programmable metamaterial

Abstract

The ability to manipulate acoustic fields in a real-time and high-resolution manner can open up many opportunities for engineering and medical applications. Realising this would demand an acoustic metamaterial that can modulate acoustic waves in a programmable manner. We achieve this goal using a crosslinked semi-crystalline polymer for which any arbitrary modulus pattern can be repeatedly encoded/erased in roughly 13 minutes. Critically and surprisingly, the material allows acoustic wave transmission with low attenuation, despite its multiphase nature. With the modulus pattern and acoustic transparency, reconfigurable phase holograms can be created. Combined with an electrically switchable and compact partitioned piezo-electric transducer, the device allows generating acoustic fields with a high modulation resolution of 10000 pixels/cm2 at an ultra-fast switching rate of 50000 fps for specified dynamic holography, far exceeding existing approaches. By programming the semi-crystalline polymer with different phase holograms, together with the selective excitation of partitioned piezo-electric transducer for incident wavefront modulation, it allows an unprecedented opportunity to create acoustic movies and remote thermal writing, with strong implications for many other future technological possibilities.