For stationary light fields, the degree of polarization (DOP) of light relates to the maximum correlation between two arbitrarily decomposed orthogonal electric field components at a space–time point. We generalize this understanding theoretically by showing a physically insightful connection between DOP and the two-time degree of coherence of electromagnetic fields. Further, by using a variable path Mach–Zehnder interferometer, we experimentally demonstrate that the DOP of light can be directly determined by measuring the correlation between orthogonal electric field components at two-time points, showing an excellent match between the experiment and the theory. This study also leads to methods for constructing a tunable DOP source.

对于静止的光场，光的偏振度（DOP）与在时空点上两个任意分解的正交电场分量之间的最大相关性有关。我们通过显示DOP和电磁场的两次相干程度之间的有物理洞察力的联系，从理论上概括了这种理解。此外，通过使用可变路径Mach–Zehnder干涉仪，我们实验证明了光的DOP可以通过测量两个时间点正交电场分量之间的相关性直接确定，这表明该实验与理论之间具有很好的匹配性。这项研究还提出了构建可调DOP源的方法。