论文标题
单纳米颗粒诱捕的狂热，不对称，超材料辅助镊子
Fano-Resonant, Asymmetric, Metamaterial-Assisted Tweezers for Single Nanoparticle Trapping
论文作者
论文摘要
等离子体纳米结构可以克服ABBE的衍射极限，从而产生强梯度场，从而有效地捕获了纳米尺寸颗粒的光学诱捕。但是，在低入射激光强度下实现稳定的捕获仍然是一项挑战。在这里，我们演示了FANO共振辅助的等离子光学镊（FAPOT），用于在一系列不对称的纳米孔径中捕获单个纳米颗粒捕获，并在50 nm的金薄膜上铣削。通过调谐捕获波长并改变入射激光强度，可以实现稳定的捕获。在接近930 nm的接近共振捕获波长下，对于20 nm聚苯乙烯颗粒的极大的归一化陷阱刚度为8.65 fn/nm/mw。我们表明，与非谐振条件相比，共振上的陷阱刚度增加了63倍。这可以归因于超小模式的体积，这可以使近场强度和腔purcell效应贡献。这些结果应促进强烈的捕获，并以低入射的诱捕激光强度，从而为研究单分子（例如蛋白质，DNA或病毒）的过渡路径提供新的选择。
Plasmonic nanostructures can overcome Abbe's diffraction limit to generate strong gradient fields, enabling efficient optical trapping of nano-sized particles. However, it remains challenging to achieve stable trapping with low incident laser intensity. Here, we demonstrate a Fano resonance-assisted plasmonic optical tweezers (FAPOT), for single nanoparticle trapping in an array of asymmetrical split nano-apertures, milled on a 50 nm gold thin film. Stable trapping is achieved by tuning the trapping wavelength and varying the incident trapping laser intensity. A very large normalized trap stiffness of 8.65 fN/nm/mW for 20 nm polystyrene particles at a near-resonance trapping wavelength of 930 nm was achieved. We show that trap stiffness on resonance is enhanced by a factor of 63 compared to off-resonance conditions. This can be attributed to the ultra-small mode volume, which enables large near-field strengths and a cavity Purcell effect contribution. These results should facilitate strong trapping with low incident trapping laser intensity, thereby providing new options for studying transition paths of single molecules, such as proteins, DNA, or viruses.
