Thresholded single-photon underwater imaging and detection

• Published in: Optics express Vol. 29; no. 18; pp. 28124 - 28133
• Main Authors: Li, Zhan-Ming, Zhou, Heng, Li, Zhong-Yuan, Yan, Zeng-Quan, Hu, Cheng-Qiu, Gao, Jun, Wu, Shi-Bao, Yin, Si-Yuan, Jin, Xian-Min
• Format: Journal Article
• Language: English
• Published: 30.08.2021
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.436013

Optical underwater target imaging and detection have been a tough but significant challenge in deep-sea exploration. Distant reflected signals drown in various underwater noises due to strong absorption and scattering, resulting in degraded image contrast and reduced detection range. Single-photon feature operating at the fundamental limit of the classical electromagnetic waves can broaden the realm of quantum technologies. Here we experimentally demonstrate a thresholded single-photon imaging and detection scheme to extract photon signals from the noisy underwater environment. We reconstruct the images obtained in a high-loss underwater environment by using photon-limited computational algorithms. Furthermore, we achieve a capability of underwater detection down to 0.8 photons per pulse at Jerlov type III water up to 50 meters, which is equivalent to more than 9 attenuation lengths. The results break the limits of classical underwater imaging and detection and may lead to many quantum-enhanced applications, like air-to-sea target tracking and deep-sea optical exploration.