Zhang Senlin, Yong Zhengdong, Shi Yaocheng, He Sailing
Centre for Optical and Electromagnetic Research, Zhejiang Provincial Key Laboratory for Sensing Technologies, JORCEP, East Building #5, Zijingang Campus, Zhejiang University, Hangzhou 310058, China.
Royal Institute of Technology (KTH), S-100 44 Stockholm, Sweden.
Sci Rep. 2016 Oct 27;6:35977. doi: 10.1038/srep35977.
A slotted nanobeam cavity (SNC) is utilized to trap a polystyrene (PS) particle with a radius of only 2 nm. The carefully designed SNC shows an ultrahigh Q factor of 4.5 × 10 while maintaining a small mode volume of 0.067(λ/n). Strongly enhanced optical trapping force is numerically demonstrated when the 2 nm PS particle is introduced into the central, slotted part of the SNC. In the vertical direction, the numerical calculation results show that a trapping stiffness of 0.4 pN/(nm · mW) around the equilibrium position and a trapping potential barrier of ~2000 kT/mW can be reached. To our best knowledge, the trapping capability (trapping stiffness and trapping potential barrier) of the proposed structure significantly outperforms the theoretical results of those in previously reported work. In addition, the SNC system does not suffer from the metal induced heat issue that restricts the performance of state-of-the-art optical trapping systems involving plasmonic enhancement. Based on the proposed cavity, applications such as lab-on-a-chip platforms for nanoscale particle trapping and analysis can be expected in future.
一种带狭缝的纳米光束腔（SNC）被用于捕获半径仅为2纳米的聚苯乙烯（PS）颗粒。精心设计的SNC显示出4.5×10的超高品质因数，同时保持0.067(λ/n)的小模式体积。当将2纳米的PS颗粒引入SNC的中央狭缝部分时，通过数值模拟证明了光捕获力得到了显著增强。在垂直方向上，数值计算结果表明，在平衡位置附近可达到0.4皮牛/(纳米·毫瓦)的捕获刚度和约2000kT/毫瓦的捕获势垒。据我们所知，所提出结构的捕获能力（捕获刚度和捕获势垒）明显优于先前报道工作中的理论结果。此外，SNC系统不存在限制涉及等离子体增强的最先进光捕获系统性能的金属诱导热问题。基于所提出的腔，未来有望实现诸如用于纳米级颗粒捕获和分析的芯片实验室平台等应用。
