Broadband achromatic metalens in terahertz regime

Qingqing Cheng; Meilin Ma; Dong Yu; Zhixiong Shen; Jingya Xie; Juncheng Wang; Nianxi Xu; Hanming Guo; Wei Hu; Shuming Wang; Tao Li; Songlin Zhuang

doi:10.1016/j.scib.2019.08.004

Broadband achromatic metalens in terahertz regime

Sci Bull (Beijing). 2019 Oct 30;64(20):1525-1531. doi: 10.1016/j.scib.2019.08.004. Epub 2019 Aug 9.

Authors

Qingqing Cheng¹, Meilin Ma², Dong Yu², Zhixiong Shen³, Jingya Xie², Juncheng Wang², Nianxi Xu⁴, Hanming Guo², Wei Hu³, Shuming Wang⁵, Tao Li⁶, Songlin Zhuang⁷

Affiliations

¹ Shanghai Key Lab of Modern Optical System and Engineering Research Center of Optical Instrument and System (Ministry of Education), University of Shanghai for Science and Technology, Shanghai 200093, China. Electronic address: qqcheng@usst.edu.cn.
² Shanghai Key Lab of Modern Optical System and Engineering Research Center of Optical Instrument and System (Ministry of Education), University of Shanghai for Science and Technology, Shanghai 200093, China.
³ National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences, School of Physics, Nanjing University, Nanjing 210093, China.
⁴ Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China.
⁵ National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences, School of Physics, Nanjing University, Nanjing 210093, China. Electronic address: wangshuming@nju.edu.cn.
⁶ National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences, School of Physics, Nanjing University, Nanjing 210093, China. Electronic address: taoli@nju.edu.cn.
⁷ Shanghai Key Lab of Modern Optical System and Engineering Research Center of Optical Instrument and System (Ministry of Education), University of Shanghai for Science and Technology, Shanghai 200093, China. Electronic address: slzhuang@yahoo.com.

PMID: 36659561
DOI: 10.1016/j.scib.2019.08.004

Abstract

Achromatic focusing is essential for broadband operation, which has recently been realised from visible to infrared wavelengths using a metasurface. Similarly, multi-terahertz functional devices can be encoded in a desired metasurface phase profile. However, metalenses suffer from larger chromatic aberrations because of the intrinsic dispersion of each unit element. Here, we propose an achromatic metalens with C-shaped unit elements working from 0.3 to 0.8 THz with a bandwidth of approximately 91% over the centre frequency. The designed metalens possesses a high working efficiency of more than 68% at the peak and a relatively high numerical aperture of 0.385. We further demonstrate the robustness of our C-shaped metalens, considering lateral shape deformations and deviations in the etching depth. Our metalens design opens an avenue for future applications of terahertz meta-devices in spectroscopy, time-of-flight tomography and hyperspectral imaging systems.

Keywords: Achromatic; Diffraction theory; Far infrared or terahertz; Metasurface.