论文标题
在反向传输矢量结构的光中保存角动量
Angular momentum conservation in counter-propagating vectorially structured light
论文作者
论文摘要
众所周知，在自由空间的行进波近期传播下，电旋转角动量和电轨道角动量是保守的。在这里，我们研究了反向传播波中的电和磁角动量，并在理论上和实验上都表明，除非在特殊情况下，都不保守任何组件。我们将这种不保守归因于电场和磁场之间的自旋旋转和轨道轨道耦合。这项工作概括了以前的发现，基于行进波，解释了反向传播的近似光线中明显的自旋轨道耦合，并扩大了我们对任意结构的光波中角动量保护的理解。
It is well-known that electric spin angular momentum and electric orbital angular momentum are conserved under paraxial propagation of travelling waves in free-space. Here we study the electric and magnetic angular momentum in counter-propagating waves and show both theoretically and experimentally that neither component alone is conserved except in special cases. We attribute this non-conservation to spin-spin and orbit-orbit coupling between the electric and magnetic fields. This work generalises previous findings based on travelling waves, explains the apparent spin-orbit coupling in counter-propagating paraxial light, and broadens our understanding of angular momentum conservation in arbitrary structured light waves.
