Disordered Elastic Metasurfaces

The discovery of the disorder effect in traditional metamaterials has opened up possibilities in the search for disordered metasurfaces. Photonic, dielectric, and elastic metamaterials that exhibit added value of the disorder effect on wave-propagation physics are reported. Despite this extensive attention and progress in disordered metamaterials, elastic metasurfaces, however, involving disorder have not yet been reported. Here, we introduce the concept of disordered elastic metasurface composed of identical pillared resonators with a random arrangement in the subwavelength range. Based on theoretical formalism and direct acoustic measurement, we observe anomalous deflection and focusing effects of flexural waves in a plate and elucidate, in detail, the related physics. This research extends the disorder effect to metasurfaces and may lead to innovative acoustoelastic devices.