Reconfigurable multifunctional acoustic metagratings enabled by local phase harnessing

Metasurfaces and metagratings show significant potential in revolutionizing acoustic devices, with applications spanning areas such as structural health monitoring and communication. Nevertheless, most previous metasurfaces are realized with limited single functions, as well as complicated structures or low transformation efficiency, leaving the reconfigurable mode-transition reflective metagratings with high efficiency largely uncharted. Here, we propose a distinctly reconfigurable phase-gradient metagrating (PGM) for wave reflection manipulations. We demonstrate that by harnessing only the local phase in the PGM, multi-functionalities can be achieved, including a transition from the perfect retro-reflection to perfect specular reflection. Moreover, we illustrate the robust full-angle incidence response for the reflection conversion enabled by the PGM. These results have been confirmed by the consistent results of theory, simulations, and experiments. The proposed reconfigurable PGM with its simple design, not only broadens the fundamental understanding of diffraction order transitions but also provides an alternative avenue for acoustic applications such as multi-functional information processing.