Flexible control of the focal spot with encoding metalens based on the digital addition principle of metasurfaces. (September 2022)

• Record Type: Journal Article
• Authors: Chen, Peng; Fang, Bo; Li, Jianmin; Wang, Zhen; Cai, Jinhui; Lu, Jianxun; Wu, Yinglai; Li, Chenxia; Jing, Xufeng
• Is Part Of: Optics and lasers in engineering. Volume 156(2022)
• Publication Date: 2022-09
• Subjects: Metamaterials -- Metasurface -- Metalens -- Deflection; Lasers in engineering -- Periodicals; Optical measurements -- Periodicals; Optics -- Periodicals; Lasers en ingénierie -- Périodiques; Mesures optiques -- Périodiques; Optique -- Périodiques; 621.36605
• DOI: 10.1016/j.optlaseng.2022.107084
• Languages: English
• ISSNs: 0143-8166

Abstract

Highlights: We propose a concept of encoding metalens based on the principle of digital addition to freely control the deflection angles of the focal spot in two-dimensional space. The Fourier convolution principle in digital signal processing is introduced to the encoding metalens sequences. The metalens and the gradient phase encoding metasurface sequences can be added to obtain a new phase arrangement of the encoding metalens. Based on the addition operation of the encoding metalens, the focus position can be flexibly adjusted. The flexible focus regulation of coded metalens based on digital addition principle can be verified by near field distribution. Abstract: We propose a concept of encoding metalens based on the principle of digital addition to freely control the deflection angles of the focal spot in two-dimensional space. Using the principle of geometric phase, by simply rotating the angle of the three-layer rectangular anisotropic structure, the transmission phase can be optimized in the range of 0–2π. We can digitally encode the unit structure to construct groups of 3-bit encoded phase gradual metasurface sequences. The Fourier convolution principle in digital signal processing is introduced to the encoding metalens sequences. The metalens and the gradient phase encoding metasurface sequences can be added to obtain a new phase arrangement of the encoding metalens. Based on the addition operation of the encoding metalens, the focus position can be flexibly adjusted. The flexible focus regulation of coded metalens based on digital addition principle can be verified by near field distribution. This provides fresh insights for the design of abnormal lens in the future, especially the multi-angle continuous free control of the focus spot.