Noise-resistant underwater correlated biphoton imaging based on a super-bunching light source

Single-photon detection (SPD) technologies have been applied to underwater optical imaging to overcome the strong attenuation of seawater.However, external photon noise, resulting from the natural light, hinders their further applications due to the extreme sensitivity of SPD and a weakly received optical signal.In this work, we performed noise-resistant underwater correlated biphoton imaging (CPI) to partly solve the influence of the external noise, through a home-built super-bunching laser generated by the stochastic nonlinear interaction between a picosecond laser and a photonic crystal fiber.Compared with a coherent laser, the probabilities of generated bundle N-photons (N 2) of the super-bunching laser have been enhanced by at least one order of magnitude, enabling CPI under weak light intensity.We experimentally demonstrated CPI with reasonable imaging contrast under the noise-to-signal ratio (NSR) up to 10 3 , and the noise-resistant performance has been improved by at least two orders of magnitude compared to that of the single-photon imaging technology.We further achieved underwater CPI with good imaging contrast under NSR of 150, in a glass tank with a length of 10 m with Jerlov type III water (an attenuation coefficient of 0.176 m -1 ).These results break the limits of underwater imaging through classical coherent lasers and may offer many enhanced imaging applications through our super-bunching laser, such as long-range target tracking and deep-sea optical exploration under noisy environments.