Elastic metasurface made of elliptic shape pillars for acoustic wave focusing

Bahram Djafari-Rouhani (1, 2) , Laurent Carpentier (1, 2) , Yan Pennec (1, 2)

1 IEMN - Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520
2 PHYSIQUE - IEMN - Physique - IEMN

We numerically propose the design of a metasurface for focusing the flexural Lamb waves propagating on a plate. The metasurface consists of a line of pillars of elliptic shape with a gradient in their ellipticity. We first determine an elliptic pillar that allows the superposition of two resonances (one compresional and one bending) in order to obtain a phase shift of 2π around the resonance. Then, the metasurface is built by chosing the ellipticity of each pillar at a given position based on the generalized Snell's law for the selected focal point. We demonstrate the capacity of this design for subwavelength focusing of the incident plane wave at any targeted point.

Mots clés: metasurface; elastic wave; focusing

Domaines: Acoustique [physics.class-ph]; Sciences de l'ingénieur [physics]; Micro et nanotechnologies/Microélectronique

Bahram Djafari-Rouhani, Laurent Carpentier, Yan Pennec. Elastic metasurface made of elliptic shape pillars for acoustic wave focusing. 2022 IEEE International Ultrasonics Symposium, IUS 2022, Oct 2022, Venise, Italy. pp.1-3, ⟨10.1109/IUS54386.2022.9957873⟩. ⟨hal-03885901⟩