Experimental realizations of full control of reflected waves with subwavelength acoustic metasurfaces

TL;DR

This paper demonstrates the analytical design and experimental realization of acoustic metasurfaces capable of arbitrarily controlling reflected waves, enabling advanced wave manipulation such as anomalous reflection and adjustable focusing.

Contribution

It introduces a novel design of subwavelength acoustic metasurfaces with full control over reflected wave phase, enabling new functionalities not achievable with traditional materials.

Findings

Successful experimental demonstration of anomalous reflection.

Realization of ultrathin planar acoustic lens with adjustable focus.

Flexible manipulation of acoustic self-accelerating beams.

Abstract

Metasurfaces with subwavelength thickness have exhibited unconventional phenomena in ways that could not be mimicked by traditional materials. Here we report the analytical design and experimental realizations of acoustic metasurface with hitherto inaccessible functionality of manipulating the reflected waves arbitrarily. By suitably designing the phase shift profile covering 2 range induced by labyrinthine units, the metasurface can reflect acoustic waves in an unusual yet controllable manner. Anomalous reflection and ultrathin planar lens with adjustable focal point were both demonstrated with carefully designed metasurfaces. Remarkably, the free manipulation of phase shifts offers great flexibility in the design of non-paraxial or paraxial acoustic self-accelerating beams with arbitrary trajectories. With the extraordinary wave-steering ability, the metasurface should open exciting possibilities for designing compact acoustic components with versatile potential and may find a variety of applications ranging from ultrasound imaging to field caustic engineering.