AUTHOR=Zhang Jiuyi , Sua Yong Meng , Hu Yongxiang , Ramanathan Jeevanandha , Huang Yu-Ping 

TITLE=Oxygen A-band absorption spectroscopy with solar photon counting and lithium niobate nanophotonic circuits

JOURNAL=Frontiers in Remote Sensing

VOLUME=3

YEAR=2022

URL=https://www.frontiersin.org/journals/remote-sensing/articles/10.3389/frsen.2022.1064244

DOI=10.3389/frsen.2022.1064244

ISSN=2673-6187

ABSTRACT=<p>Oxygen A-band measurements can provide important information about cloud top height, cloud physical and optical thickness, and surface atmospheric pressure. So far, O<sub>2</sub> A-band measurements are typically made with spectrometers at a spectral resolution of 40 p.m. (such as in the OCO-2 satellite) or a coarser resolution. This paper reports a new CubeSat measurement concept with higher spectral resolution over the O<sub>2</sub> A-band using integrated photonic circuits and solar photon counting techniques. An integrated Micro-ring filter (MRR) chip with 10 p.m. resonant linewidth with an extinction ratio of 25 dB or higher is designed, fabricated, and used for precise measurements of the atmospheric oxygen A-band absorption line-shapes around 770 nm. With solar-photon counting and using a narrow-band filter made of an integrated, fast-swept MRR on lithium niobate on insulator (LNOI), we have demonstrated a high-resolution measurement of the O<sub>2</sub> A-band absorption spectrum, exhibiting good agreement with the HITRAN database.</p>