Tiny but universal beam shifts occur when a polarized light beam is reflected upon a planar interface. Although the beam shifts of Gaussian beams have been measured by the weak measurement technique, the weak measurement for orbital angular momentum (OAM)-induced spatial shifts of vortex beams is still missing. Here, by elaborately choosing the preselection and postselection states, the tiny OAM-induced Goos–Hanchen and Imbert–Fedorov shifts are amplified at an air–prism interface. The maximum shifts along directions both parallel and perpendicular to the incident plane are theoretically predicted and experimentally verified with optimal preselection and postselection states. These maximum shifts can be used to determine the OAM of vortex beams.

中文翻译：

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光学反射中轨道角动量引起的光束位移的优化弱测量

当偏振光束在平面界面上反射时，会发生微小但普遍的光束偏移。尽管已经通过弱测量技术测量了高斯光束的光束位移，但仍然缺少对轨道角动量（OAM）引起的涡旋光束空间位移的弱测量。在这里，通过精心选择预选和后选状态，微小的 OAM 引起的 Goos-Hanchen 和 Imbert-Fedorov 位移在空气棱镜界面被放大。沿着平行和垂直于入射平面的方向的最大位移在理论上预测，并通过最佳预选和后选状态进行实验验证。这些最大偏移可用于确定涡旋光束的 OAM。