A wide field-of-hearing metalens for aberration-free sound capture

Metalenses, as a designer tool for manipulating waves, has demonstrated remarkable capabilities thus far. However, their performance is limited to normal incidence and they exhibit significant sensitivity to oblique incidence. This sensitivity often leads to a decrease in focusing efficiency due to coma aberration, posing a considerable challenge. Here, we present a novel solution in the form of a wide field-of-hearing (FOH) metalens, specifically designed for capturing and focusing sound without aberration. To overcome the limitations of conventional metalenses, we propose a hybridized metalens that combines Helmholtz and zigzag building blocks. By incorporating both complete phase modulation and unitary transmission, this hybrid metalens achieves superior performance. We conduct experimental validations to demonstrate the proof-of-concept sound reception, thereby introducing the concept of wide FOH monitoring systems. The rational design of this metalens holds great versatility and can be implemented across various platforms. Its applications potentially span diverse fields such as energy harvesting, monitoring, sensing, imaging, and communication in auditory and submerged environments.