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.
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.
Correlation imaging based on entangled light sources offers potential benefits over classical single-photon imaging (SPI) in noisy environments, but also faces challenges such as low brightness, long integration times, and difficulty imaging biological organisms. Here, we propose noise-resistant biologically correlated biphoton imaging (CPI) based on a super-bunching light source, addressing the challenge of severe signal-to-noise ratio degradation in conventional SPI schemes. Our CPI, based on a super-bunching light source with high brightness, broadband spectrum (400–1100 nm), and strong quantum correlation (g 2 (0) ∼ 250), delivers high-performance, noise-resistant operation by extracting correlated photon pairs between the reference and signal paths. Experimental results show that under extreme noise conditions (noise-to-signal ratio up to 600), the structural profile in conventional SPI is entirely obscured by noise. In contrast, CPI still clearly resolves the target structure. Quantitative analysis further reveals that, as noise intensity increases, the imaging visibility of CPI can be enhanced by more than two orders of magnitude compared to SPI schemes. This study confirms the exceptional robustness and practical utility of super-bunching light-based correlated imaging in high-noise environments, offering an effective technical approach for high-quality biological observation in complex optical conditions.
Abstract Accurate detection and identification of space-based faint targets under strong background is a pressing challenge for all‑weather deep space exploration. However, active deep space detection is often hampered by the disturbances of intense stellar stray light and multi-source heterogeneous noise, making it difficult to achieve noise‑blind source separation and accurate identification of weak target signals under extremely low signal-to-noise ratio. To address these challenges, we develop a random dynamic mask modulation scheme to enhance higher-order coherence, unveiling power-law photon number distributions and super-bunching correlations that enable higher-order photon correlation imaging with a single-photon detector array (SPDA). The imaging scheme decouples the target signal from multi-source disturbances including coherent, thermal, and super-bunching light, as well as multiple background noises such as shot noise, environmental stray light, and dark counts. Here, we experimentally demonstrate a super-bunching light with a fiftieth-order photon correlation of 1.45×10 72 at a mean photon number , achieving a 10 42 enhancement in the high-to-second-order correlation ratio. The super-bunching light source enables continuously tunable output intensity from ultra‑weak to extremely bright, overcoming the limitation of conventional sources that produce only ultra‑weak photon numbers. Strikingly, we observe the ratio R n >2 of the multiphoton probability between the signal power-law light and a noise coherent laser reaching 5.29×10 269 at for 281 photons. The contrast in higher-order photon correlation imaging reaches 0.99, increasing by 0.26 over the second-order case. At an imaging exposure time of 5 µs and a mean photon number , we achieve 512×512‑pixel SPDA imaging with a dynamic range of 252.93 dB despite simultaneous photon‑starved signal and intense background. Our noise‑blind scheme establishes ultra‑wide dynamic range, high‑speed, sub-megapixel single‑photon imaging under multi‑source noise and intense optical disturbances, opening new routes for space surveillance and quantum‑enhanced detection.
ABSTRACT Quantum‐correlated techniques enable high‐contrast and super‐resolution imaging through the feature of correlated photons. The superbunching effect with a second‐order correlation larger than 2, i.e., g (2) (0) > 2, demonstrates the existence of strong correlations between photons, which can enable stray light resistance and achieve high‐contrast imaging. Here, we present a scheme for quantum correlated imaging using single colloidal quantum dots (CQDs) with strong superbunching emission. The optimized CdSe/ZnS CQDs with g (2) (0) up to 69 and 20 under continuous‐wave and pulsed laser excitation have been prepared. We achieved noise‐resistant correlated biphoton imaging (CPI) based on single CQDs with noise intensity 104 times stronger than their photoluminescence. By modulating photoluminescence intensity, the Fourier‐domain CPI was determined with reasonably good contrast, despite noise 75 600 times stronger than biphoton counts. Our proposal may enable laboratory‐based quantum imaging to be applied to real‐world applications with the desired suppression of intense stray light.
Single photon–level imaging at 1550 nanometers is a key driver for crucial advancements in the next-generation laser detection technology. This cutting-edge approach plays a vital role in space ranging, target recognition, and three-dimensional remote sensing. However, it has faced severe challenges such as insufficient noise-tolerant performance. Here, we introduced noise-tolerant correlated coincidence imaging (CCI) based on supercorrelated light (SCL). The light source, generated through nonlinear interaction between a pulsed laser and a photonic crystal fiber, exhibits a broader power-law photon number probability distribution and extremely strong photon correlation [with second-order correlation function g (2) (0) up to 18,166]. Our noise-tolerant CCI can resist random environmental noise up to 100,000 times stronger than the echo signal photons. SCL offers an exceptionally strong noise tolerance for single photon–level imaging in extreme environments with intense noise, paving the way for the future development of extremely sensitive light detection.
ABSTRACT High‐performance single‐photon light detection and ranging (LiDAR) technology with robust noise resistance provides a powerful means for environmental perception in extreme scenarios. Here, we propose a parallel photon‐correlation (PPC) LiDAR driven by super‐bunching light, enabling noise‐resistant parallel detection in the single‐photon‐counting regime. Using super‐bunching light with g (2) (0) = 177, we demonstrate robust photon‐correlation imaging at a signal‐to‐background ratio (SBR) of 1:2750 in the 2D parallel imaging experiment, and also achieve noise‐resistant three‐dimensional (3D) target reconstruction. Leveraging the correlation between the reference and echo signals, PPC LiDAR enables parallel ranging up to 165 m in a single‐channel, beyond the distance threshold limited by the pulse period. In the outdoor imaging experiment, parallel imaging over 40 m was achieved. By combining 10‐channel parallel detection with robust noise resistance, PPC LiDAR provides a light‐source‐based solution for single‐photon LiDAR operation under extreme conditions, distinct from experimental quantum illumination. Our PPC LiDAR scheme opens a new pathway toward the next generation of high‐performance environmental perception technology.
As an important part of underwater optical technology, underwater imaging plays a crucial role in accurately capturing underwater targets and environmental features. Facing the challenges of complex ocean environments and severe photon attenuation, quantum imaging breaks through the limitations of traditional optical imaging technology by utilizing the characteristics of two-photon entanglement and time-space correlation, thus offering a new perspective on ocean turbulence. To this end, we propose a new underwater entangled-photon quantum imaging system. Specifically, we first construct an entangled photon quantum imaging physical model through ocean long-exposure turbulence and then exploit an entangled light coincidence imaging reconstruction method to image the target object. Furthermore, in response to the problem that ocean environment has a great impact on photons, we develop a photon capture probability method based on entangled photon pairs to reduce the impact of the ocean turbulence noise on imaging and improve the underwater target imaging resolution. We experimentally demonstrate the effectiveness of our method by showing that even in harsh ocean environments, quantum imaging performs superior resolution capabilities over traditional light source imaging techniques.