We propose a perfectly reflecting acoustic metasurface which is designed by replacing the curved segments of the traditional Fresnel reflector by flat Fano-resonant sub-wavelength unit cells. To preserve the original Fresnel focusing mechanism, the unit cell phase follows a specific phase profile which is obtained by applying the generalized Snell's law and Fermat's principle. The reflected curved phase fronts are thus created at the air-metasurface boundary by tailoring the metasurface dispersion as dictated by Huygens' principle. Since the unit cells are implemented by sub-wavelength double slit-shaped cavity resonators, the impinging sound waves are perfectly reflected producing acoustic focusing with negligible absorption. We use plane-wave solution and full-wave simulations to demonstrate the focusing effects. The simulation results closely follow the analytical predictions.
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Research Article| April 10 2018
A perfect Fresnel acoustic reflector implemented by a Fano-resonant metascreen
Special Collection: Acoustic Metamaterials and Metasurfaces
M. Amin, O. Siddiqui, M. Farhat, A. Khelif; A perfect Fresnel acoustic reflector implemented by a Fano-resonant metascreen. J. Appl. Phys. 14 April 2018; 123 (14): 144502. https://doi.org/10.1063/1.5012012
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