Roques-Carmes Charles, Fan Shanhui, Miller David A B
E. L. Ginzton Laboratory, Stanford University, 348 Via Pueblo, Stanford, CA, 94305, USA.
Light Sci Appl. 2024 Sep 20;13(1):260. doi: 10.1038/s41377-024-01622-y.
Optical phenomena always display some degree of partial coherence between their respective degrees of freedom. Partial coherence is of particular interest in multimodal systems, where classical and quantum correlations between spatial, polarization, and spectral degrees of freedom can lead to fascinating phenomena (e.g., entanglement) and be leveraged for advanced imaging and sensing modalities (e.g., in hyperspectral, polarization, and ghost imaging). Here, we present a universal method to analyze, process, and generate spatially partially coherent light in multimode systems by using self-configuring optical networks. Our method relies on cascaded self-configuring layers whose average power outputs are sequentially optimized. Once optimized, the network separates the input light into its mutually incoherent components, which is formally equivalent to a diagonalization of the input density matrix. We illustrate our method with numerical simulations of Mach-Zehnder interferometer arrays and show how this method can be used to perform partially coherent environmental light sensing, generation of multimode partially coherent light with arbitrary coherency matrices, and unscrambling of quantum optical mixtures. We provide guidelines for the experimental realization of this method, including the influence of losses, paving the way for self-configuring photonic devices that can automatically learn optimal modal representations of partially coherent light fields.
光学现象在其各自的自由度之间总是表现出一定程度的部分相干性。部分相干性在多模态系统中尤为引人关注，在这类系统中，空间、偏振和光谱自由度之间的经典和量子关联可导致迷人的现象（例如，纠缠），并可用于先进的成像和传感模式（例如，在高光谱、偏振和鬼成像中）。在此，我们提出一种通用方法，通过使用自配置光学网络来分析、处理和生成多模系统中空间部分相干光。我们的方法依赖于级联的自配置层，其平均功率输出会依次进行优化。一旦优化完成，该网络会将输入光分离为相互非相干的分量，这在形式上等同于输入密度矩阵的对角化。我们通过马赫 - 曾德尔干涉仪阵列的数值模拟来说明我们的方法，并展示该方法如何用于执行部分相干环境光传感、生成具有任意相干矩阵的多模部分相干光以及解扰量子光学混合态。我们提供了该方法实验实现的指导方针，包括损耗的影响，为能够自动学习部分相干光场最佳模态表示的自配置光子器件铺平了道路。
