Zhang Xiaohe, Rui Guanghao, He Jun, Cui Yiping, Gu Bing
Opt Lett. 2021 Jan 1;46(1):110-113. doi: 10.1364/OL.411216.
Vortex beams carrying optical angular momentum (AM) could drive the orbital motion of a small particle around the optical axis. In general, the orbital rotation speed of trapped particles increases linearly with the increasing laser power. Beyond the linear optics regime, in this work, we investigate both the optical force and torque on a two-photon absorbing Rayleigh particle produced by the tightly focused femtosecond-pulsed circularly polarized vortex beam. Different from the trapping dynamics of particles without two-photon absorption (TPA), it is shown that the orbital motion of trapped particles with TPA accelerates nonlinearly as the laser power increases. Moreover, the orbital motion acceleration of trapped particles is proportional to the TPA coefficient. The corresponding underlying mechanism is discussed in detail. Our results may find interesting applications in the characterization of the optical nonlinearity of a single nanoparticle, and AM manipulation and particle transportation in the nonlinear optics regime.
携带光学角动量（AM）的涡旋光束可以驱动小粒子绕光轴做轨道运动。一般来说，捕获粒子的轨道旋转速度随激光功率的增加而线性增加。在超越线性光学范围的情况下，在这项工作中，我们研究了由紧聚焦飞秒脉冲圆偏振涡旋光束产生的双光子吸收瑞利粒子上的光学力和扭矩。与无双光子吸收（TPA）的粒子捕获动力学不同，结果表明，具有TPA的捕获粒子的轨道运动会随着激光功率的增加而非线性加速。此外，捕获粒子的轨道运动加速度与TPA系数成正比。详细讨论了相应的潜在机制。我们的结果可能在单个纳米粒子光学非线性的表征以及非线性光学范围内的角动量操纵和粒子传输方面找到有趣的应用。
