Helle Øystein Ivar, Ahluwalia Balpreet Singh, Hellesø Olav Gaute
Opt Express. 2015 Mar 9;23(5):6601-12. doi: 10.1364/OE.23.006601.
Optical waveguides can be used to trap and transport micro-particles. The particles are held close to the waveguide surface by the evanescent field and propelled forward. We propose a new technique to lift and trap particles above the surface of the waveguides. This is made possible by a gap between two opposing, planar waveguides. The field emitted from each of the waveguide ends diverge fast, away from the substrate and into the cover-medium. By combining two fields propagating at an angle upwards and coming from opposite sides of a gap, particles can be stably lifted and trapped at the crossing of the two fields. Thus, particles are transported by waveguides leading to a gap, where they are lifted away from the substrate and trapped. The experiments are supported by numerical simulations of the forces on the micro-particles. Fluorescence imaging is used to track the particles in 3D with a precision of 50 nm.
光波导可用于捕获和传输微粒。微粒通过倏逝场被保持在靠近波导表面的位置并向前推进。我们提出了一种新技术，可将微粒提升并捕获在波导表面上方。这是通过两个相对的平面波导之间的间隙实现的。从每个波导端部发射的场迅速发散，远离衬底并进入覆盖介质。通过组合从间隙相对两侧以向上角度传播的两个场，微粒可以在两个场的交叉处被稳定地提升和捕获。因此，微粒由通向间隙的波导传输，在间隙处它们被从衬底提升并捕获。实验得到了对微粒上力的数值模拟的支持。荧光成像用于以50纳米的精度在三维空间中跟踪微粒。
