Broadband Achromatic Metalenses With High Focusing Efficiency Based on Inverse Design
Junjing Huang, Enge Zhang, Lei Zhang, Xiaofeng Duan, Kai Liu, Yongqing Huang, Xiaomin Ren
Abstract
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 xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <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 xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <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.