Elmore Family School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN 47907, USA.
School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China.
Sci Adv. 2023 Jan 27;9(4):eade4203. doi: 10.1126/sciadv.ade4203.
Spinning thermal radiation is a unique phenomenon observed in condensed astronomical objects, including the Wolf-Rayet star EZ-CMa and the red degenerate star G99-47, due to the existence of strong magnetic fields. Here, by designing symmetry-broken metasurfaces, we demonstrate that spinning thermal radiation with a nonvanishing optical helicity can be realized even without applying a magnetic field. We design nonvanishing optical helicity by engineering a dispersionless band that emits omnidirectional spinning thermal radiation, where our design reaches 39% of the fundamental limit. Our results firmly suggest that metasurfaces can impart spin coherence in the incoherent radiation excited by thermal fluctuations. The symmetry-based design strategy also provides a general pathway for controlling thermal radiation in its temporal and spin coherence.
螺旋热辐射是在凝聚态天文物体中观察到的一种独特现象，包括沃尔夫-拉叶星 EZ-CMa 和红简并星 G99-47，这是由于存在强磁场。在这里，通过设计对称破缺的超表面，我们证明了即使没有施加磁场，也可以实现具有非零光学螺旋度的螺旋热辐射。我们通过设计一个具有各向同性发射的无弥散能带来实现非零光学螺旋度，我们的设计达到了基本极限的 39%。我们的结果有力地表明，超表面可以在由热涨落激发的非相干辐射中赋予自旋相干性。基于对称性的设计策略还为控制热辐射的时间和自旋相干性提供了一种通用途径。
