Achromatic acoustic generalized phase-reversal zone plates

Abstract

We report an achromatic acoustic generalized phase-reversal zone plate by harnessing the response of dipole and monopole, which eliminate the chromatic aberration of conventional zone plates. The focusing properties of the proposed metalens are compared with that of the conventional Soret-type Fresnel zone plate (FZP) in both experiments and simulations. Due to the combination of the phase-reversal characteristic and the tunable transmission phase induced by dipole and monopole, an achromatic high efficient focusing is confirmed by experiment in the frequency range from $3350$ to $3950\rm{Hz}$, with the focal intensity of achromatic metalens being approximately twice that of Soret-type FZP. The proposed achromatic metalens has potential applications in the broad field of acoustics, such as imaging and energy harvesting.

Compact meta-differentiator for achieving isotropically high-contrast ultrasonic imaging

“…This confirms that the spatial differentiator excels in isotropic edge detection, achieving a maximum resolution of 1.125 mm at the operating wavelength of 1.5 mm. Supplementary Note 10 also reveals the performance of the 2D meta-differentiator at various excitation frequencies, where the imaging plane dynamically shifts with the variations in excitation frequency, similar to that of the Fresnel zone plates 56,57 . However, our meta-differentiator consistently excels in its core capability of edge detection across a spectrum of frequency adjustments.…”