Zhang Zhibin, Min Changjun, Fu Yanan, Zhang Yuquan, Liu Weiwei, Yuan Xiaocong
Opt Express. 2021 Feb 15;29(4):6282-6292. doi: 10.1364/OE.418900.
Waveguide optical tweezers can capture and transport nanoparticles, and have important applications in biology, physics, and materials science. However, traditional waveguide optical tweezers need to couple incident light into one end of the waveguide, which causes problems such as difficulty in alignment and low efficiency. Here, we propose a new type of waveguide optical tweezers based on spin-orbit coupling of light. Under the effect of spin-orbit coupling between the waveguide and nearby particles illuminated by a circularly polarized light, the particles experience a lateral recoil force and a strong optical gradient force, which make particles in a large area to be trapped near the waveguide and then transmitted along the waveguide, avoiding the coupling of light into one end of the waveguide. We further demonstrate that the particles can be transmitted along a curved waveguide and even rotated along a ring-shaped waveguide, and its transmission direction can be simply switched by adjusting the spin polarization of incident light. This work has significance in the research of optical on-chip nano-tweezers.
波导光镊可以捕获和传输纳米粒子，在生物学、物理学和材料科学等领域有着重要应用。然而，传统的波导光镊需要将入射光耦合到波导的一端，这会导致对准困难和效率低下等问题。在此，我们提出一种基于光的自旋-轨道耦合的新型波导光镊。在圆偏振光照射下，波导与附近粒子之间的自旋-轨道耦合作用下，粒子会受到横向反冲力和强大的光学梯度力，这使得大面积的粒子被捕获在波导附近，然后沿着波导传输，避免了光耦合到波导的一端。我们进一步证明，粒子可以沿着弯曲的波导传输，甚至可以沿着环形波导旋转，并且通过调整入射光的自旋偏振可以简单地切换其传输方向。这项工作在片上光学纳米镊子的研究中具有重要意义。
