Achromatic acoustic generalized phase-reversal zone plates

Abstract

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 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.