Coherence Entropy Unlocks Insights into Light-Field Behavior

Environments like turbulent atmospheres or deformed optical systems can distort and disrupt the light field, making it difficult to achieve clear and reliable results. Researchers at Soochow University have uncovered details on how light behaves as it travels through complex and fluctuating media. The work could provide opportunities to advance various applications ranging from optical communications to advanced imaging techniques.

The researchers leveraged a concept known as coherence entropy to overcome the deformation, flicker, and drift of light fields caused by complex media that have historically limited practical applications.

Artistic rendering of the partially coherent light superimposed by incoherent modes as it passes through complex media. Courtesy of Soochow University/Chengliang Zhao.

Coherence entropy, a measure of the statistical property of light known as coherence, provides a global characterization of light fields subjected to random fluctuations. Traditionally, characterizing the coherence of light has been complex and difficult to quantify. The research team successfully applied orthogonal modal decomposition to partially coherent beams, leading to the introduction of coherence entropy as a reliable metric.

Their study revealed that coherence entropy remains stable during the propagation of light through a unitary system, even when faced with complex and deformed optical environments. This consistency suggests that coherence entropy can be a robust indicator of light field behavior in non-ideal conditions.

The team demonstrated the practical utility of coherence entropy by examining its effectiveness in partially coherent beams as they moved through various deformed optical systems and turbulent media. The results show that coherence entropy is resilient and remains a dependable measure for evaluating the performance of light fields in challenging conditions.

According to corresponding author and lead researcher Chengliang Zhao, the work represents a major leap forward in the ability to predict and control light propagation through complex environments. Introducing coherence entropy as a global coherence characteristic, he said, opens possibilities to customize light fields for better performance in real-world applications.

The implications of this study are far-reaching. From enhancing optical communication systems that must operate through atmospheric turbulence to advancing imaging technologies that rely on light fields traveling through distorted media, coherence entropy could become a crucial tool for scientists and engineers alike.

By providing a more reliable way to assess and manage light fields in less-than-ideal conditions, this research paves the way for broader and more effective use of low-coherence light fields across various scientific and practical domains.

The research was published in Advanced Photonics (www.doi.org/10.1117/1.AP.6.4.046002).