Design of a broadband metamaterial-based acoustic lens using elaborated carpet cloak strategy

• DOI: 10.1007/s00339-021-05043-1
• Publication Date: 2021-11-08T15:05:43Z
• Authors: Sajad Eslamzadeh; Mohsen Ghaffari-Miab; Bijan Abbasi-Arand
• Keywords: Cloak; Directivity

Generating plane waves for sonar systems is of high value due to their directive nature. In this paper, first, the unidirectional carpet cloak theory will be elaborated for converting arbitrary wavefronts to plane waves and collimating transmitted energy. Next, as an specific case study, converting cylindrical waves to plane waves will be demonstrated. Broadband capability of pentamode metasurfaces along with impedance matching has made these structures desirable for experimental underwater applications. Finally, an acoustic cylindrical-to-plane-wave conversion system based on pentamode metamaterials (PMs) will be demonstrated. This system is composed of a line source along with the proposed broadband lens which is more reasonable than complicated and high-cost array of transducers for generating plane waves. A broadband isotropic PM unit-cell is exploited to realize the abovementioned acoustic lens. The proposed device which operates decently in a broad frequency range, from sub-kHz to $$20\,kHz$$ , has potential applications including beamforming, focusing, detection, surveying and positioning in sonar systems and biomedical imaging.