Sun Kaili, Yang Bingxiong, Cai Yangjian, Kivshar Yuri, Han Zhanghua
Shandong Provincial Key Laboratory of Optics and Photonic Devices, Center of Light Manipulation and Applications, School of Physics and Electronics, Shandong Normal University, Jinan 250358, China.
Interdisciplinary Research Center, Liaoning Academy of Materials, Shenyang 110167, China.
Sci Adv. 2025 Aug;11(31):eadw0986. doi: 10.1126/sciadv.adw0986. Epub 2025 Jul 30.
Achieving circularly polarized thermal emissions with high spatiotemporal coherence using planar structures has long been considered to be elusive. Here, we use nonlocal metasurfaces with monoclinic lattices that break mirror symmetry to efficiently achieve circularly polarized thermal emissions with both high temporal and spatial coherence. We design a chiral metasurface based on waveguide arrays with periodically shifted segments that have a saddle-shaped chiral and high- dispersion band. The parabolic shape along one direction ensures minimum involvement of spatial/Fourier components at each frequency, thereby achieving circularly polarized thermal emission with high spatial coherence. Meanwhile, the flatband behavior along the other direction allows the use of a slot-shaped spatial filter and a mid-infrared lens to collect emissions from large-area metasurfaces, thus improving power collection efficiency without affecting temporal coherence. Our experiments demonstrate circularly polarized thermal emissions with high temporal coherence ( > 200) and very large circular dichroism (~0.8).
长期以来，利用平面结构实现具有高时空相干性的圆偏振热辐射一直被认为难以实现。在此，我们使用具有单斜晶格的非局域超表面，这种晶格打破了镜面对称性，从而有效地实现了具有高时间和空间相干性的圆偏振热辐射。我们基于具有周期性移位段的波导阵列设计了一种手性超表面，这些段具有鞍形手性和高色散带。沿一个方向的抛物线形状确保了每个频率下空间/傅里叶分量的最小参与，从而实现具有高空间相干性的圆偏振热辐射。同时，沿另一个方向的平带行为允许使用狭缝形空间滤波器和中红外透镜来收集大面积超表面的辐射，从而在不影响时间相干性的情况下提高功率收集效率。我们的实验展示了具有高时间相干性（>200）和非常大的圆二色性（约0.8）的圆偏振热辐射。
