针对金属纳米光镊结构进行捕获时存在的光热效应问题,设计了一种硅基双纳米球的光镊结构。采用基于三维频域有限元的算法,对比分析了硅基双纳米球与金基双纳米球结构的增强场分布以及在对聚苯乙烯颗粒捕获势能相同条件下的热效应,发现硅基结构具有发热小、在高光场强度下捕获稳定性好的优点。对所设计的硅基双纳米球结构对聚苯乙烯颗粒的捕获特性进行模拟分析,在稳态场下研究了不同直径颗粒在不同位置受到的捕获力情况。研究结果表明,硅基纳米光镊结构在对微粒进行稳定捕获的同时可有效降低结构热效应带来的影响。

In order to solve the problem that there exists the photothermal effect during the trapping by a metal optical nanotweezer structure, an optical tweezer structure with silicon-based double nanoballs is designed. The three-dimensional finite element method in frequency domain is used to compare and analyze the enhanced field distributions as well as the thermal effects under the same trapping potential energy of polystyrene nanoparticles for the structures with silicon-based double nanoballs and with gold-based double nanoballs. It is found that the silicon-based structure has a relatively low thermal effect and good trapping stability under a high light field intensity. The trapping of polystyrene nanoparticles by the designed silicon-based double nanoballs is simulated, and the trapping forces under a stable field at different positions of nanoparticles with different diameters are studied. The research results show that the silicon-based optical nanotweezer structure can trap nanoparticles stably and simultaneously suppress the structural thermal effects efficiently.