Broadband achromatic meta-lens based on height variation in the near-infrared spectrum

Abstract

Compared with metal nano-antennas metalens, the dielectric metalens has better optical characteristics in the optical band, has smaller ohmic loss, and is more advantageous. In addition, the problem of dispersion of metalens in the wide-band range has been a hot issue that experts have been scrambling to study in recent years. In view of the excellent transmission characteristics of silicon in the near-infrared region, the optical properties of rectangular silicon nano-antennas in the near-infrared region are re-examined and simulated. And using simulation software to model and analyze it, a broadband achromatic dielectric metalens in the near-infrared band based on height variation to adjust the phase is designed. The paper demonstrates the broadband achromatic focusing characteristics of its working in transmission mode, its focusing efficiency can be as high as nearly 69%, and the focal length remains basically unchanged when λ is from 950 to 1100nm. It is a new sub-wavelength non-planar structure based on height variation, offering important opportunities for applications in circular polarized optics, fiber sensors, laser scanning fluorescence microscopy, optical signal transmission, and integrated on-chip devices in the forthcoming future.