论文标题
通过旋转角度动量转换增强近场光学镊子
Enhancing Near-Field Optical Tweezers by Spin-to-Orbital Angular Momentum Conversion
论文作者
论文摘要
近场的光模式为纳米素，微生物学和纳米技术的多种应用中的光学陷阱，输送和分类单纳西颗粒提供了一种方法。使用严格的电磁理论，我们研究了携带自旋和轨道角动量的近场光学镊子的力和捕获性能。假定捕获场是在大多数发射光都是evansevencent的条件下在玻璃水接口处的总内反射显微镜物镜生成的。我们发现了这些镊子的新颖方面，包括旋转和稳定捕获纳米镜珠的可能性。更重要的是，我们表明，在近场条件下，自旋和轨道角动量对小颗粒旋转的贡献几乎是等效的，在符号相反的情况下开放了它们相互取消的可能性。我们表明，这些条件导致最佳的光学诱捕，从而产生极有效的光学镊子，用于纳米流动，具有圆形对称性和相对较弱的旋转。
Near-field patterns of light provide a way to optically trap, deliver and sort single nanoscopic particles in a wide variety of applications in nanophotonics, microbiology and nanotechnology. Using rigorous electromagnetic theory, we investigate the forces and trapping performance of near-field optical tweezers carrying spin and orbital angular momenta. The trapping field is assumed to be generated by a total internal reflection microscope objective at a glass-water interface in conditions where most of the transmitted light is evanescent. We find novel aspects of these tweezers, including the possibility to rotate and stably trap nanoscopic beads. More importantly, we show that, under near-field conditions, the contributions of of spin and orbital angular momenta to the rotation of small particles are almost equivalent, opening the possibility to cancel each other when they have opposite sign. We show that these conditions result in optimal optical trapping, giving rise to extremely effective optical tweezers for nanomanipulation, having both circular symmetry and relatively weak rotation.
