We investigate the dynamics of Si spherical nanoparticles for different infrared wavelengths in a system based on two circularly polarized counter-propagating Gaussian beams. Through the analysis of the dipolar and quadrupolar forces, we obtain several conditions under which these nanoparticles describe different types of attractive or repulsive spirals at focus plane depending on the efficiency of the quadrupole trap obtained. We demonstrate that these spirals are generated by the angular momentum transfer from the electromagnetic field to the particles, and this is mainly due to the interference forces dipole–dipole and quadrupole–dipole. Through the adequate selection of the wavelength, angular momentum transfer can only take place with quadrupolar–dipolar interference forces. We study particle dynamics by solving the deterministic and non-deterministic over-damped Langevin equation.

我们研究了基于两个圆极化反向传播的高斯光束的系统中不同红外波长的Si球形纳米粒子的动力学。通过分析偶极和四极力，我们获得了几种条件，在这些条件下，根据获得的四极阱的效率，这些纳米粒子在聚焦平面上描述了不同类型的吸引或排斥螺旋。我们证明了这些螺旋是由从电磁场到粒子的角动量传递产生的，这主要是由于偶极-偶极和四极-偶极的干扰力。通过波长适当的挑选，角动量转移只能采取与四极偶极干扰力的地方。