Directional Acoustic Superscattering by Coupled Resonators

The phenomenon known as $s\phantom{\rule{0}{0ex}}u\phantom{\rule{0}{0ex}}p\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}s\phantom{\rule{0}{0ex}}c\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}g$ maximizes interaction between incident waves and subwavelength structures, enabling a myriad of applications, including sensing and energy harvesting. It is difficult to extend optical superscattering (based on core-shell multilayered structures) to its acoustic counterpart, though, due to limited material availability. This study demonstrates acoustic superscattering by means of subwavelength scatterers, each consisting of a rigid cylinder decorated with deeply subwavelength resonators. The results provide a critical understanding of superscattering, in both optics and acoustics, that could strongly boost sensing technology.