Evidence of a broadband gap in a phononic crystal strip

We experimentally demonstrate a very large ultrasonic band gap in a one-dimensional phononic crystal. The structure consists of periodic tungsten pillars fixed to a tailored silicon strip with a layer of epoxy. Combining local resonances and Bragg scattering, the gap ranges from 450kHz to 1250kHz, w...

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Bibliographic Details
Published in:Ultrasonics 2017-07, Vol.78, p.51-56
Main Authors: Coffy, Etienne, Euphrasie, Sébastien, Addouche, Mahmoud, Vairac, Pascal, Khelif, Abdelkrim
Format: Article
Language:English
Subjects:
Acoustics
Engineering Sciences
Large band gap
Local resonances
Materials
Micro and nanotechnologies
Microelectronics
Phononic strip
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Summary:We experimentally demonstrate a very large ultrasonic band gap in a one-dimensional phononic crystal. The structure consists of periodic tungsten pillars fixed to a tailored silicon strip with a layer of epoxy. Combining local resonances and Bragg scattering, the gap ranges from 450kHz to 1250kHz, which corresponds to a gap-to-midgap ratio of 94%, and the attenuation exceeds 35dB with only three periods. Numerical calculations with the Finite Element Method are performed to support the analysis and provide a better understanding of the behavior of the structure. In particular, the role of the thin layer of epoxy is studied and is shown to have a strong influence on the dispersion. This phononic structure with a very large band gap can be considered as a new tool to design acoustic devices with high performances.
ISSN:0041-624X
1874-9968
DOI:10.1016/j.ultras.2017.03.003