Photon-counting distributed free-space spectroscopy

Saifen Yu; Zhen Zhang; Haiyun Xia; Xiankang Dou; Tengfei Wu; Yihua Hu; Manyi Li; Mingjia Shangguan; Tianwen Wei; Lijie Zhao; Lu Wang; Pu Jiang; Chengjun Zhang; Lixing You; Leigang Tao; Jiawei Qiu

doi:10.1038/s41377-021-00650-2

^{Photon-counting distributed free-space spectroscopy}

Light Sci Appl. 2021 Oct 12;10(1):212. doi: 10.1038/s41377-021-00650-2.

Authors

Saifen Yu^#^{1

2}, Zhen Zhang^#^{1

2}, Haiyun Xia^{3

4

5}, Xiankang Dou^{1

6}, Tengfei Wu⁷, Yihua Hu⁸, Manyi Li¹, Mingjia Shangguan⁹, Tianwen Wei¹, Lijie Zhao¹, Lu Wang¹, Pu Jiang¹, Chengjun Zhang¹⁰, Lixing You¹⁰, Leigang Tao⁶, Jiawei Qiu²

Affiliations

¹ School of Earth and Space Science, University of Science and Technology of China, 230026, Hefei, China.
² School of Atmospheric Physics, Nanjing University of Information Science & Technology, 210044, Nanjing, China.
³ School of Earth and Space Science, University of Science and Technology of China, 230026, Hefei, China. hsia@ustc.edu.cn.
⁴ School of Atmospheric Physics, Nanjing University of Information Science & Technology, 210044, Nanjing, China. hsia@ustc.edu.cn.
⁵ Hefei National Laboratory for Physical Sciences at the Microscale, 230026, Heifei, China. hsia@ustc.edu.cn.
⁶ Hefei National Laboratory for Physical Sciences at the Microscale, 230026, Heifei, China.
⁷ Changcheng Institute of Metrology & Measurement, Aviation Industry Corporation of China, 100095, Beijing, China.
⁸ State Key Laboratory of Pulsed Power Laser Technology, National University of Defense Technology, 230037, Hefei, China.
⁹ State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, 361102, Xiamen, China.
¹⁰ Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 200050, Shanghai, China.

^# Contributed equally.

Abstract

Spectroscopy is a well-established nonintrusive tool that has played an important role in identifying and quantifying substances, from quantum descriptions to chemical and biomedical diagnostics. Challenges exist in accurate spectrum analysis in free space, which hinders us from understanding the composition of multiple gases and the chemical processes in the atmosphere. A photon-counting distributed free-space spectroscopy is proposed and demonstrated using lidar technique, incorporating a comb-referenced frequency-scanning laser and a superconducting nanowire single-photon detector. It is suitable for remote spectrum analysis with a range resolution over a wide band. As an example, a continuous field experiment is carried out over 72 h to obtain the spectra of carbon dioxide (CO₂) and semi-heavy water (HDO, isotopic water vapor) in 6 km, with a range resolution of 60 m and a time resolution of 10 min. Compared to the methods that obtain only column-integrated spectra over kilometer-scale, the range resolution is improved by 2-3 orders of magnitude in this work. The CO₂ and HDO concentrations are retrieved from the spectra acquired with uncertainties as low as ±1.2% and ±14.3%, respectively. This method holds much promise for increasing knowledge of atmospheric environment and chemistry researches, especially in terms of the evolution of complex molecular spectra in open areas.