Resonant tunneling compression and evanescent wave amplification by an acoustic metalens

We have demonstrated an acoustic metamaterial (AM) metalens with the anisotropic refractive index cavities based on the space-coiling units. Compared to that based on conventional Fabry-Perot (FP) resonance, the proposed space-coiling units significantly downsize the thickness of the AM metalens. In the cavities, we further demonstrated a strong resonant tunneling compression effect, which can be used to substantially magnify the evanescent waves to realize subwavelength imaging. Imaging experiments have shown that the objects located at a considerably enlarged distance away from the input surface of the AM metalens can be imaged with a subwavelength spatial resolution. The proposed AM metalens may facilitate potential applications in acoustic super-resolution imaging and focusing devices. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study presented an acoustic metamaterial (AM) metalens with anisotropic refractive index cavities based on space-coiling units for subwavelength imaging. Compared to traditional Fabry-Perot (FP) resonance, the proposed space-coiling units reduced the thickness of the AM metalens significantly. A resonant tunneling compression effect in the cavities enhanced the resolution of imaging objects located far from the input surface.