Full-dimensional complex coherence properties tomography for multi-cipher information security

Optical coherence is a fundamental property of light, playing a key role in understanding interference, propagation, and light-matter interactions for both classical and quantum light. Measuring the coherence properties of an optical field is crucial for a wide range of applications. However, despite many proposed measurement schemes, significant challenges still remain. In this work, we present a protocol to measure the full-dimensional coherence properties of a partially coherent beam. The method is based on tomographing the complex coherent modes of the partially coherent field within its coherence time. Once the complex coherent modes are reconstructed, all coherence properties including field correlation and its higher-order correlations (e.g., intensity correlation) can be recovered for beams that are either spatially uniformly or non-uniformly correlated. We perform a proof-of-principle experiment to measure the complex field correlation and intensity correlation of a structured partially coherent beam synthesized by random modes. Additionally, we discuss the application of full-dimensional complex coherence function tomography in coherence-based multi-cipher information security. The robustness of our system in complex environments is also evaluated.