近日，厦门大学的陈理想及其研究团队取得一项新进展。经过不懈努力，他们揭示了具有任意方向轨道角动量时空涡旋脉冲在平面反射和折射下的质心移位。相关研究成果已于2024年3月11日在国际知名学术期刊《物理评论A》上发表。

该研究团队解析推导了携带任意方向轨道角动量的三维时空涡旋波包的移位表达式。研究人员发现光学构型(如入射角、折射率等)对移位的影响可以用变形张量来描述，而波包结构的影响则是各向同性的。有趣的是，由拓扑电荷引起的空间和角移位可以分别归因于球体上两个拓扑上不同的切向量场。

同时，研究人员对横向线性动量和垂直角动量的守恒定律也进行了讨论。这项研究可能会在时空脉冲整形方面发现潜力，并为最近关于时空涡旋脉冲固有轨道角动量定义的争论提供线索。

据悉，波包在横向或时空平面上的涡旋结构可以显著增强波包在反射和折射过程中的移位。这些移位分为六种类型：入射平面内的Goos-Hnchen移位，垂直于入射平面的Imbert-Fedorov移位，纵向移位以及角移位的三种对应类型。

附：英文原文

Title: Centroid shifts of spatiotemporal vortex pulses with arbitrarily oriented orbital angular momentum at planar reflection and refraction

Author: Fangqing Tang, Lixiang Chen

Issue&Volume: 2024/03/11

Abstract: The vortex structure of wave packets on the transversal or spatiotemporal plane can significantly enhance their shifts during the reflection and refraction. These shifts are classified into six types: Goos-Hnchen shift within the plane of incidence, Imbert-Fedorov shift perpendicular to the plane of incidence, longitudinal shift, together with three counterparts of angular shifts. Here, we analytically derive the expressions for these shifts for three-dimensional spatiotemporal vortex wave packets that carry orbital angular momentum of arbitrary orientation. It is found that the influence of the optical configurations (e.g., incident angle, refractive index, etc.) on the shifts can be described by a deformation tensor, while that of the wave-packet structure is an isotropic one. Interestingly, the spatial and angular shifts induced by the topological charge can be attributed to two topologically distinct tangent vector fields on the spheres, respectively. Also, the conservation laws of transverse linear momentum and vertical angular momentum are revisited. Our studies may find potential in spatiotemporal pulse shaping and shed light on the recent controversy regarding the definition of intrinsic orbital angular momentum for a spatiotemporal vortex pulse.

DOI: 10.1103/PhysRevA.109.033512

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.109.03351