Abstract
We designed a gradient acoustic metasurface to manipulate acoustic wavefront freely. The broad bandwidth and high efficiency transmission are achieved by the acoustic metasurface which is constructed with a series of unit cells to provide desired discrete acoustic velocity distribution. Each unit cell is composed of a decorated metal plate with four periodically arrayed Helmholtz resonators (HRs) and a single slit. The design employs a gradient velocity to redirect refracted wave and the impedance matching between the metasurface and the background medium can be realized by adjusting the slit width of unit cell. The theoretical and numerical results show that some excellent wavefront manipulations are demonstrated by anomalous refraction, non-diffracting Bessel beam, sub-wavelength flat focusing, and effective tunable acoustic negative refraction. Our designed structure may offer potential applications for the imaging system, beam steering and acoustic lens.
Highlights
Recent years have witnessed intense investigation of acoustic metasurface capable of realizing general wavefront modulation[1,2,3,4,5,6,7,8,9]
Cells based on Helmholtz resonators (HRs)[27,28,29], which are composed of a decorated metal plate with four periodically arrayed HRs and a single slit at the right side
We firstly illustrate the construction of the gradient acoustic velocity metasurface
Summary
Recent years have witnessed intense investigation of acoustic metasurface capable of realizing general wavefront modulation[1,2,3,4,5,6,7,8,9]. The metasurface on the basis of the two-dimensional (2D) pentamode metamaterial has been introduced and fabricated[12] This kind of metasurface with gradient velocity provides a new design methodology for acoustic wave modulation and realizes a well matched impedance to improve the transmission efficiency. Successful wavefront manipulations, such as anomalous refraction, non-diffracting Bessel beam and flat lens have been demonstrated with the pentamode metasurface. Theoretical analysis and numerical calculation show that the proposed metasurface will be able to realize four distinct wavefront manipulations: anomalous refraction, non-diffracting Bessel beam, sub-wavelength flat focusing, and effective tunable acoustic negative refraction All of these four properties are analyzed with the theoretical descriptions through the generalized Snell’s law. Our gradient velocity metasurface developed here helps to offer a new design methodology for acoustic wavefront engineering
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call