Wang Haotian, Wu Xiang, Shen Deyuan
Opt Express. 2015 Oct 19;23(21):27650-60. doi: 10.1364/OE.23.027650.
We propose a tunable optical trapping system for nanoparticles based on generating standing wave by coupling two coherent beams into a ring resonator in opposite directions, respectively. The distributions of the mode field excited in three types of the ring-resonators-based trapping systems (microring, microdisk and slot ring) and the corresponding optical forces on the nanoparticles are calculated numerically. By the stability analysis in all directions, the smallest size of the particles could be stably trapped under the Brownian motion in the microring resonator is 61.2 nm when the input power is 10 mW, and the azimuthal orientations of the trapped particles are depended on the phase difference between the two input beams. On the other hand, the appearance of high order radial modes in the microdisk resonator enables a tunable radial trapping. To improve the trapping capability for the smaller particles, we utilize the slot ring resonator to make full use of the optical power and the trapping size could be minimized to ~29 nm when the input power is also set as 10 mW.
我们提出了一种用于纳米粒子的可调谐光阱系统，该系统基于分别将两束相干光束沿相反方向耦合到环形谐振器中以产生驻波。数值计算了在三种基于环形谐振器的捕获系统（微环、微盘和狭缝环）中激发的模式场分布以及纳米粒子上相应的光力。通过全方位的稳定性分析，当输入功率为10 mW时，在微环谐振器中，布朗运动下能够稳定捕获的最小粒子尺寸为61.2 nm，并且捕获粒子的方位取向取决于两束输入光束之间的相位差。另一方面，微盘谐振器中高阶径向模式的出现实现了可调谐的径向捕获。为了提高对较小粒子的捕获能力，我们利用狭缝环谐振器充分利用光功率，当输入功率也设置为10 mW时，捕获尺寸可最小化至约29 nm。
