Multi-parameter independent manipulation for flexural wave by notched metasurface

There are two severe limitations of current flexural wave metasurface based on local resonance mechanism or modal conversion method: low transmittance and only a single manipulation parameter. Inspired by the interaction between notches and flexural waves, we propose a high transmittance and multi-parameter independent manipulation metasurface composed of an array notches. Firstly, based on the phase shift accumulation method, a full 2 pi phase shift is achieved by modulating four notch parameters independently. Secondly, the refraction and focusing metasurfaces are designed based on the generalized Snell's law and compared with the simulation results. Finally, the designed focusing metasurfaces is validated by corresponding experiments. The four metasurfaces have a good performance for broadband flexural wave focusing, and the numerical and experimental focal lengths are in great agreement with the theoretical values. The notched metasurface provides an innovative way to manipulate flexural waves without resonators, which can be used in the applications of energy harvesting, waveguide design and ultrasonic detection.