Sharma Abhinav, Xie Shangran, Russell Philip St J
Opt Lett. 2021 Aug 15;46(16):3909-3912. doi: 10.1364/OL.421885.
Optical binding of microparticles offers a versatile playground for investigating the optomechanics of levitated multi-particle systems. We report millimeter-range optical binding of polystyrene microparticles in hollow-core photonic crystal fiber. The first particle scatters the incident mode into several modes, creating a beat pattern that exerts a position-dependent force on the second particle. Particle binding results from the interplay of the forces created by counterpropagating beams. A femtosecond trapping laser is used so that group velocity walk-off eliminates disturbance caused by higher order modes accidentally excited at the fiber input. The inter-particle distance can be optically switched over 2 orders of magnitude (from 42 µm to 3 mm), and the bound particle pairs can be translated along the fiber by unbalancing the powers in the counterpropagating trapping beams. The frequency response of a bound particle pair is investigated at low gas pressure by driving with an intensity-modulated control beam. The system offers new degrees of freedom for manipulating the dynamics and configurations of optically levitated microparticle arrays.
微粒的光学束缚为研究悬浮多粒子系统的光力学提供了一个多功能的平台。我们报道了在空心光子晶体光纤中实现毫米级聚苯乙烯微粒的光学束缚。第一个粒子将入射模式散射成几个模式，产生一个拍频图案，该图案对第二个粒子施加一个与位置有关的力。粒子束缚是由反向传播光束产生的力之间的相互作用导致的。使用飞秒俘获激光，以便群速度走离消除由光纤输入端意外激发的高阶模式引起的干扰。粒子间距离可通过光学方式在2个数量级范围内切换（从42微米到3毫米），并且通过使反向传播俘获光束中的功率不平衡，可使束缚的粒子对沿光纤平移。在低气压下，通过用强度调制的控制光束驱动来研究束缚粒子对的频率响应。该系统为操纵光学悬浮微粒阵列的动力学和构型提供了新的自由度。
