Broadband Achromatic Metalens in the Visible Light Spectrum Based on Fresnel Zone Spatial Multiplexing

Abstract

Metalenses composed of a large number of subwavelength nanostructures provide the possibility for the miniaturization and integration of the optical system. Broadband polarization-insensitive achromatic metalenses in the visible light spectrum have attracted researchers because of their wide applications in optical integrated imaging. This paper proposes a polarization-insensitive achromatic metalens operating over a continuous bandwidth from 470 nm to 700 nm. The silicon nitride nanopillars of 488 nm and 632.8 nm are interleaved by Fresnel zone spatial multiplexing method, and the particle swarm algorithm is used to optimize the phase compensation. The maximum time-bandwidth product in the phase library is 17.63. The designed focal length can be maintained in the visible light range from 470 nm to 700 nm. The average focusing efficiency reaches 31.71%. The metalens can achieve broadband achromatization using only one shape of nanopillar, which is simple in design and easy to fabricate. The proposed metalens is expected to play an important role in microscopic imaging, cameras, and other fields.

Metalens in Improving Imaging Quality: Advancements, Challenges, and Prospects for Future Display

“…For resonant-phase achromatic metalens, the transmission wavefront and group delay can be altered simultaneously by changing the geometric parameters of resonant-phase metaatoms. [156] Aieta et al, for example, proposed the optical mode of dense spectrum based on the low-loss dielectric resonator and obtained dispersion phase compensation in 2015. [19] Khorasaninejad et al developed an achromatic metalens in 2019 that can be configured to work in reflection mode, as shown in Figure 14 (b).…”

Full-Color Imaging System Based on the Joint Integration of a Metalens and Neural Network

“…Here, three wavelengths of 462 nm, 511 nm, and 606 nm were selected for the achromatic metalens design in the visible band. The phase factors of the three wavelengths were optimized and initialized by the particle swarm optimization (PSO) algorithm [ 42 ]. Then, the phase factors were fine-tuned by using end-to-end network imaging.…”