Daria Vincent R, Palima Darwin Z, Glückstad Jesper
ARC Centre for Quantum-Atom Optics, Australian National University, ACT, Australia.
Opt Express. 2011 Jan 17;19(2):476-81. doi: 10.1364/OE.19.000476.
Light beams with helical phase profile correspond to photons having orbital angular momentum (OAM). A Laguerre-Gaussian (LG) beam is an example where its helical phase sets a phase-singularity at the optical axis and forms a ring-shaped transverse amplitude profile. Here, we describe a unique beam where both phase and amplitude express a helical profile as the beam propagates in free space. Such a beam can be accurately referred to as an optical twister. We characterize optical twisters and demonstrate their capacity to induce spiral motion on particles trapped along the twisters' path. Unlike LG beams, the far field projection of the twisted optical beam maintains a high photon concentration even at higher values of topological charge. Optical twisters have therefore profound applications to fundamental studies of light and atoms such as in quantum entanglement of the OAM, toroidal traps for cold atoms and for optical manipulation of microscopic particles.
具有螺旋相位分布的光束对应于具有轨道角动量（OAM）的光子。拉盖尔 - 高斯（LG）光束就是一个例子，其螺旋相位在光轴上设置了一个相位奇点，并形成环形横向振幅分布。在此，我们描述一种独特的光束，当它在自由空间中传播时，其相位和振幅都呈现螺旋分布。这样的光束可以准确地称为光学扭转器。我们对光学扭转器进行了表征，并展示了它们能够在沿扭转器路径捕获的粒子上诱导螺旋运动的能力。与LG光束不同，扭曲光束的远场投影即使在拓扑电荷值较高时也能保持高光子浓度。因此，光学扭转器在光和原子的基础研究中有着深远的应用，例如在OAM的量子纠缠、冷原子的环形陷阱以及微观粒子的光学操纵等方面。
