双环径向偏振涡旋光束的粒子捕获

摘要

In this paper,the optical trapping characteristics of a highly focused double-ring radially polarized (R-TEM*11 )vortex beam acting on a Rayleigh particle are studied theoretically.It is shown that a bright spot with high peak intensity and a small three-dimensional (3 D)dark spot surrounded by a high optical wall can be obtained in the focal re-gion by choosing a proper truncation parameterβof the R-TEM*11 vortex beam.Based on the Rayleigh scattering theory, the gradient,absorbing and scattering forces acting on a gold particle and an air bubble with the highly focused R-TEM*11 vortex beam have been studied.The trapping stability is calculated and analyzed in detail.It is found that a Rayleigh particle whose refractive index is larger or smaller than that of the ambient can be stably trapped by a highly focused R-TEM*11 vortex beam with β=1.1 and 1.6,respectively.%本文研究了紧聚焦的双环径向偏振（R-TEM*11）涡旋光束对瑞利粒子的捕获特性。通过调节R-TEM*11涡旋光束的截断参数β，可以在焦点附近得到中心强度较大的三维亮斑和面积较小而且被亮场包围的三维暗斑。基于瑞利散射理论，研究了该光束作用在金属微粒和空气泡粒子上的梯度力、吸收力和散射力的分布特点，讨论了粒子捕获的稳定性。结果表明：调节R-TEM*11涡旋光束的截断参数β，当β＝1．1时，产生的亮焦斑可以稳定地捕获折射率较大的金属粒子；当β＝1．6时，产生的暗焦斑可以稳定地捕获折射率较小的空气泡粒子。