DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark, Lyngby, Denmark.
Phys Rev Lett. 2011 Nov 11;107(20):203601. doi: 10.1103/PhysRevLett.107.203601. Epub 2011 Nov 10.
Usually a light beam pushes a particle when the photons act upon it. We investigate the optical forces by nonparaxial gradientless beams and find that the forces can drag suitable particles all the way towards the light source. The major criterion of realizing the backward dragging force is the strong nonparaxiality of the light beam, which contributes to the pulling force owing to momentum conservation. The nonparaxiality of the Bessel beam can be manipulated to possess a dragging force along both the radial longitudinal directions, i.e., a "tractor beam" with stable trajectories is achieved.
通常情况下，当光子作用于粒子时，光束会推动粒子。我们研究了无傍轴梯度光束的光力，发现光力可以将合适的粒子一路拖向光源。实现向后拖拽力的主要条件是光束的强非傍轴性，这有助于由于动量守恒而产生拉力。贝塞尔光束的非傍轴性可以被操纵以在径向纵向方向上都具有拖拽力，即实现了具有稳定轨迹的“牵引光束”。
