Brzobohatý Oto, Šiler Martin, Trojek Jan, Chvátal Lukáš, Karásek Vítězslav, Zemánek Pavel
Opt Express. 2015 Apr 6;23(7):8179-89. doi: 10.1364/OE.23.008179.
We present the results of a theoretical analysis focused on three-dimensional optical trapping of non-spherical gold nanoparticles using a tightly focused laser beam (i.e. optical tweezers). We investigate how the wavelength of the trapping beam enhances trapping stiffness and determines the stable orientation of nonspherical nanoparticles in the optical trap which reveals the optimal trapping wavelength. We consider nanoparticles with diameters being between 20 nm and 254 nm illuminated by a highly focused laser beam at wavelength 1064 nm and compare our results based on the coupled-dipole method with published theoretical and experimental data. We demonstrate that by considering the non-spherical morphology of the nanoparticle we can explain the experimentally observed three-dimensional trapping of plasmonic nanoparticles with size higher than 170 nm. These results will contribute to a better understanding of the trapping and alignment of real metal nanoparticles in optical tweezers and their applications as optically controllable nanosources of heat or probes of weak forces and torques.
我们展示了一项理论分析的结果，该分析聚焦于使用紧聚焦激光束（即光镊）对非球形金纳米颗粒进行三维光学捕获。我们研究了捕获光束的波长如何增强捕获刚度，并确定非球形纳米颗粒在光阱中的稳定取向，从而揭示了最佳捕获波长。我们考虑直径在20纳米至254纳米之间的纳米颗粒，由波长为1064纳米的高度聚焦激光束照射，并将基于耦合偶极子方法的结果与已发表的理论和实验数据进行比较。我们证明，通过考虑纳米颗粒的非球形形态，可以解释实验观察到的尺寸大于170纳米的等离子体纳米颗粒的三维捕获。这些结果将有助于更好地理解实际金属纳米颗粒在光镊中的捕获和排列，以及它们作为热的光学可控纳米源或弱力和扭矩探针的应用。
