The quantum statistical properties of optical fields are core parameters that characterize the intrinsic physical properties of light sources, among which the second-order degree of coherence g(2)(0) serves as a key criterion for distinguishing between different types of light such as thermal light and coherent light, and thus holds significant theoretical and practical value. The quantum correlation characteristics inherent in these properties provide crucial physical support for advanced fields including quantum spectroscopy and quantum imaging. Particularly in correlation imaging, this technique exhibits irreplaceable potential for complex scene detection, owing to its strong resistance to scattering interference and exceptional capability for high-resolution imaging under weak-light conditions. However, existing technologies are still constrained by several critical limitations, including the limited stability of sources with a high degree of coherence, insufficient manipulation speed and control over light intensity, a lack of synergy between coherent control and mode customization, poor adaptability to low-light conditions, and lagging capabilities in the analysis of high-order coherence control.
In response to the aforementioned issues, this study employs a Single-Photon Detection Array (SPDA) as the core detection device and proposes two schemes for enhancing the second-order coherence of a light field: an innovative approach based on random dynamic mask modulation and a comparative scheme using a Hadamard mask. By spatially modulating a coherent light field with an initial second-order coherence of 1, a light beam exhibiting both strong correlations and power-law statistical properties is successfully generated. Throughout the investigation, the photon statistical distribution and second-order coherence characteristics of the modulated light were systematically examined, with emphasis placed on analyzing the influence of key parameters such as exposure time and mask modulation frequency, while the enhancement effect of this modulation technique on single-photon correlation imaging performance was also experimentally validated.
Experimental results demonstrate that the proposed scheme achieves significant effectiveness in both light field manipulation and imaging optimization. In terms of photon statistical property control, the proposed method enables efficient manipulation of light fields with average photon numbers ranging from 10-2 to 102. The photon number statistics of the modulated light field strictly adhere to a discrete power-law distribution, and its distribution curve exhibits a distinct linear relationship within a specific interval in double logarithmic coordinates. This finding provides critical support for the quantitative analysis of quantum statistical properties in highly coherent light fields. Regarding the enhancement of second-order coherence and imaging performance optimization, under short exposure conditions (5 μs), the random dynamic mask can elevate the second-order coherence of the initial coherent light field to 98.6667, with an average photon number per pixel of only 0.0076, while the Hadamard mask can increase it to 47.2899, corresponding to an average photon number per pixel of 0.0137. Further experimental validation confirms that the g⁽²⁾ correlation imaging scheme based on the second-order coherence significantly outperforms the traditional frame stacking approach in all performance metrics. With the proposed scheme, only 20 frames are required to achieve substantial improvement in imaging quality. Specifically, compared to the traditional frame stacking method, loading the random dynamic mask results in the following performance enhancements: the peak signal-to-noise ratio (PSNR) increases by 20.98 dB, the structural similarity (SSIM) improves by 0.84, the contrast (CTRS) enhances by 73.97, and the sharpness (ACU) rises by 34.01 compared to the initial value.
In summary, the modulation and imaging scheme proposed in this study can effectively optimize the performance of single-photon detection array under conditions of low photon flux and short exposure, providing a feasible approach for high-quality imaging in low-light scenarios. Meanwhile, experimental results fully demonstrate the core role of high-coherence light fields in promoting the performance of single-photon correlation imaging, which holds significant reference value for the practical application of quantum imaging technology.