Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Nano Lett. 2012 May 9;12(5):2347-51. doi: 10.1021/nl300301x. Epub 2012 Apr 18.
We demonstrate an increase in trapping lifetime for optically trapped nanoparticles by more than an order of magnitude using feedback control, with no corresponding increase in beam power. Langevin dynamics simulations were used to design the control law, and this technique was then demonstrated experimentally using 100 nm gold particles and 350 nm silica particles. No particle escapes were detected with the controller on, leading to lower limits on the increase in lifetime for 100 nm gold particles of 26 times (at constant average beam power) and 22 times for 350 nm silica particles (with average beam power reduced by one-third). The approach described here can be combined with other techniques, such as counter propagating beams or higher-order optical modes, to trap the smallest nanoparticles and can be used to reduce optical heating of particles that are susceptible to photodamage, such as biological systems.
我们通过使用反馈控制，将光阱中纳米粒子的俘获寿命延长了一个数量级以上，而光束功率没有相应增加。朗之万动力学模拟用于设计控制律，然后使用 100nm 金粒子和 350nm 二氧化硅粒子进行了实验验证。控制器开启时，没有粒子逃逸，因此 100nm 金粒子的寿命延长下限为 26 倍（在平均光束功率不变的情况下），350nm 二氧化硅粒子的寿命延长下限为 22 倍（平均光束功率降低三分之一）。这里描述的方法可以与其他技术结合使用，例如反向传播光束或更高阶的光学模式，以捕获最小的纳米粒子，并可用于减少对光损伤敏感的粒子（如生物系统）的光学加热。
