Ding Ping, Lu Menglong, Lu Liangchen, Wen Jiquan, Gong Xue, Zheng Hongxia, Chen Huajin
Opt Lett. 2024 Oct 1;49(19):5655-5658. doi: 10.1364/OL.532684.
We propose that a transition from positive optical torque (OT) to negative OT occurs in a dipolar nanoparticle subjected to a simple optical field composed of two circularly polarized plane waves. This phenomenon can be observed in a phase-change nanoparticle comprising insulating and metallic phases. The analytical expression based on the multipole expansion theory reveals that the positive OT in the metallic phase originates from the electric response during light-matter interaction. However, in the insulating phase, the magnetic response is excited, leading to a significant negative OT due to the contribution of the magnetic field-magnetic dipole interaction. It is noted that the phenomenon of reversible transverse OT is robust to the angle between two constituent plane waves, ensuring its practical application.
我们提出，在受到由两个圆偏振平面波组成的简单光场作用的偶极纳米粒子中，会发生从正光扭矩（OT）到负OT的转变。这种现象可以在由绝缘相和金属相组成的相变纳米粒子中观察到。基于多极展开理论的解析表达式表明，金属相中的正OT源于光与物质相互作用期间的电响应。然而，在绝缘相中，磁响应被激发，由于磁场 - 磁偶极相互作用的贡献导致显著的负OT。需要注意的是，可逆横向OT现象对于两个组成平面波之间的角度具有鲁棒性，确保了其实际应用。
