Single-layer metalens for achromatic focusing with wide field of view in the visible range

Abstract

Metalenses have attracted extensive attention due to their capability of flexible wavefront manipulation by subwavelength nanostructures. However, the development of metalenses has been deeply limited by the field of view (FOV) and spectral bandwidth. Existing wide FOV and achromatic metalenses usually adopt cascaded metasurfaces to correct aberrations, resulting in inevitable challenges for nano-fabrication technologies. In this paper, we design a wide FOV metalens with a numerical aperture of 0.24 which can provide a diffraction-limited FOV for over 40° at three discrete wavelengths of 473 nm (blue), 532 nm (green), and 632.8 nm (red). The metalens involves only a single layer of metasurface integrated on a flat substrate to correct aberration. This method considerably simplifies the architectures compared with the cascaded metalenses and conventional bulky optical systems. In addition, an achromatic wide FOV metalens with an operating wavelength range from 492 to 592 nm is further designed to demonstrate the generality of the proposed method. The simulated results indicate that metalenses have a great achromatic and diffraction-limited focusing performance within a large incident angle region, which is expected to have promising applications in imaging, holography, machine vision, and other fields.