Broadband Achromatic Metalenses With High Focusing Efficiency Based on Inverse Design

• Published in: IEEE photonics technology letters Vol. 35; no. 23; pp. 1255 - 1258
• Main Authors: Huang, Junjing, Zhang, Enge, Zhang, Lei, Duan, Xiaofeng, Liu, Kai, Huang, Yongqing, Ren, Xiaomin
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.12.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: achromatic; Algorithms; Arrayed waveguide gratings; Broadband; Couplings; Efficiency; Focusing; Incident light; Inverse design; Metalens; Optical polarization; Optical receivers; Optical surface waves; Sun; Transmissivity; velocity-varying climbing particle swarm optimization
• ISSN: 1041-1135; 1941-0174
• DOI: 10.1109/LPT.2023.3314624

In this letter, we propose a broadband achromatic metalens that exhibits high focusing efficiency within the wavelength range of 1270-2070 nm and is insensitive to polarization. Within the operating wavelength range, the metalens displays a focal length shift of only <inline-formula> <tex-math notation="LaTeX">\pm 0.5~\mu \text{m} </tex-math></inline-formula> and exhibits excellent achromatic properties. The average focusing efficiency of the metalens is 56%, with a maximum focusing efficiency of 70.7%. Compare with no metalens, the metalens can enhance the transmissivity of incident light by approximately 10%. And the average full width at half maximum (FWHM) of this structure is <inline-formula> <tex-math notation="LaTeX">0.5526~\mu \text{m} </tex-math></inline-formula>. In the design process, we propose a new algorithm. The concept behind this method has significant implications for other inverse design algorithms.