Transverse spinning of unpolarized light
Transverse spinning of unpolarized light
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DOI：
10.1038/s41566-020-00733-3
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发表时间：
2020-12-21
期刊：
影响因子：
35
通讯作者：
Bliokh, K. Y.
中科院分区：
文献类型：
--
作者：
Eismann, J. S.;Nicholls, L. H.;Bliokh, K. Y.
众所周知，光的自旋角动量，以及光子的自旋角动量，与它们的圆偏振直接相关。自然地，对于完全非偏振光，偏振是不确定的，自旋消失。然而，对于非傍轴光，最近发现的横向自旋分量，正交于主传播方向，在很大程度上是独立的偏振态的波。在这里，我们证明，无论是理论上和实验上，这种横向自旋生存，即使在非傍轴领域（例如，集中或消逝）产生的完全非偏振傍轴光。这种违反直觉的现象与二维（2D）傍轴场和3D非傍轴场的“完全去极化”含义之间的根本差异密切相关。我们的研究结果为利用非偏振光研究自旋相关现象和光学操纵开辟了一条途径。
It is well known that the spin angular momentum of light, and therefore that of photons, is directly related to their circular polarization. Naturally, for totally unpolarized light, polarization is undefined and the spin vanishes. However, for non-paraxial light, the recently discovered transverse spin component, orthogonal to the main propagation direction, is largely independent of the polarization state of the wave. Here, we demonstrate, both theoretically and experimentally, that this transverse spin survives even in non-paraxial fields (for example, focused or evanescent) generated from totally unpolarized paraxial light. This counterintuitive phenomenon is closely related to the fundamental difference between the meanings of 'full depolarization' for two-dimensional (2D) paraxial and 3D non-paraxial fields. Our results open an avenue for studies of spin-related phenomena and optical manipulation using unpolarized light.