Bareil Paul B, Sheng Yunlong
Center for Optics, Photonics and Lasers, Laval University, Quebec G1K 7P4, Canada.
Opt Express. 2010 Dec 6;18(25):26388-98. doi: 10.1364/OE.18.026388.
We analyze the trap stiffness and trapping force potential for a nano-cylinder trapped in the optical tweezers against its axial and lateral shift and tilt associated to the natural Brownian motion. We explain the physical properties of the optical trapping by computing and integrating the radiation stress distribution on the nano-cylinder surfaces using the T-matrix approach. Our computation shows that the force stiffness to the lateral shift is several times higher than that to the axial shift of the nano-cylinder, and lateral torque due to the stress on the side-face is 1-2 orders of magnitude higher than that on the end-faces of a nano-cylinder with the aspect ratio of 2 - 20. The torque due to the stress on the nano-cylinder surface is 2-3 orders of magnitude higher than the spin torque. We explain why a nano-cylinder of low aspect ratio is trapped and aligned normal to the trapping beam axis.
我们分析了被光镊捕获的纳米圆柱体在与其自然布朗运动相关的轴向、横向位移和倾斜情况下的阱刚度和捕获力势。我们使用T矩阵方法计算并积分纳米圆柱体表面的辐射应力分布，从而解释光阱的物理特性。我们的计算表明，纳米圆柱体横向位移的力刚度比轴向位移的力刚度高几倍，对于长径比为2至20的纳米圆柱体，侧面应力产生的横向扭矩比端面应力产生的横向扭矩高1至2个数量级。纳米圆柱体表面应力产生的扭矩比自旋扭矩高2至3个数量级。我们解释了为什么低长径比的纳米圆柱体会被捕获并垂直于捕获光束轴排列。
