Optical Trapping of Double-Ring Radially Polarized Beam with Improved Axial Trapping Efficiency

• 作者: 严绍辉 叶彤 姚保利 赵卫
• 来源期刊: 中国物理快报(英文版)
• 学科: 工学
• 关键词: 线性偏振光 光束 径向 捕集效率 轴向 环形 光阱 传播方向
• 年，卷（期）: 2010,（10）
• 页码范围: 224-227
• 页数: 4页
• 分类号: TH133.3 TN253
• 语种: 英文

摘要

Radially polarized beams, focused by a high numerical aperture (NA) objective, have non-propagating fields along the propagation axis in the focal region, which leads to a higher axial trapping efficiency in comparison with linearly polarized beams. We propose a design for converting a lowest-order radially polarized beam (R-TEM01) to a double-ring radial polarization distribution (DR R-TEM01) through a specially designed polarization rotator. The phases of the two rings of this beam differ by π. Numerical results evaluated by rigorous T-matrix method show that the DR R-TEM01 beam can improve the axial trapping efficiency compared with the R-TEM01 beam, provided that the size of trapped particles is of order of the wavelength of the beam.