We experimentally and theoretically characterize dielectric nano- and microparticle orbital motion induced by an optical vortex of the Laguerre-Gaussian beam. The key to stable orbiting of dielectric nanoparticles is hydrodynamic inter-particle interaction and microscale confinement of slit-like fluidic channels. As the number of particles in the orbit increases, the hydrodynamic inter-particle interaction accelerates orbital motion to overcome the inherent thermal fluctuation. The microscale confinement in the beam propagation direction helps to increase the number of trapped particles by reducing their probability of escape from the optical trap. The diameter of the orbit increases as the azimuthal mode of the optical vortex increases, but the orbital speed is shown to be insensitive to the azimuthal mode, provided that the number density of the particles in the orbit is same. We use experiments, simulation, and theory to quantify and compare the contributions of thermal fluctuation such as diffusion coefficients, optical forces, and hydrodynamic inter-particle interaction, and show that the hydrodynamic effect is significant for circumferential motion. The optical vortex beam with hydrodynamic inter-particle interaction and microscale confinement will contribute to biosciences and nanotechnology by aiding in developing new methods of manipulating dielectric and nanoscale biological samples in optical trapping communities.

中文翻译：

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流体动力粒子间相互作用对由光学涡旋驱动的介电纳米粒子轨道运动的影响。

我们在实验上和理论上描述了由Laguerre-Gaussian光束的光学涡旋引起的介电纳米和微粒轨道运动。介电纳米粒子稳定轨道的关键是流体动力学的粒子间相互作用和狭缝状流体通道的微观限制。随着轨道中粒子数量的增加，流体动力学粒子间相互作用会加速轨道运动，从而克服固有的热波动。在光束传播方向上的微米级限制有助于减少被捕获粒子从光阱中逸出的可能性，从而增加被捕获粒子的数量。轨道的直径随光学涡旋的方位角模式的增加而增加，但是轨道速度显示出对方位角模式不敏感，前提是轨道中粒子的数量密度相同。我们使用实验，模拟和理论来量化和比较热波动的影响，例如扩散系数，光学力和流体动力粒子间的相互作用，并表明流体动力效应对于圆周运动很重要。具有流体动力学的粒子间相互作用和微尺度约束的光学涡旋光束将通过帮助开发在光捕获社区中操纵介电和纳米尺度生物样本的新方法，为生物科学和纳米技术做出贡献。和流体动力学的粒子间相互作用，并表明流体动力学效应对于圆周运动具有重要意义。具有流体动力学的粒子间相互作用和微尺度约束的光学涡旋光束将通过帮助开发在光捕获社区中操纵介电和纳米尺度生物样本的新方法，为生物科学和纳米技术做出贡献。和流体动力学的粒子间相互作用，并表明流体动力学效应对于圆周运动具有重要意义。具有流体动力学的粒子间相互作用和微尺度约束的光学涡旋光束将通过帮助开发在光捕获社区中操纵介电和纳米尺度生物样本的新方法，为生物科学和纳米技术做出贡献。