Reversal of optical binding force by Fano resonance in plasmonic nanorod heterodimer.
Reversal of optical binding force by Fano resonance in plasmonic nanorod heterodimer.
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DOI：
10.1364/oe.21.006601
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发表时间：
2013-03
期刊：
影响因子：
3.8
通讯作者：
Q. Zhang;J. Xiao;X. Zhang;Y. Yao;H. Liu
中科院分区：
文献类型：
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作者：
Q. Zhang;J. Xiao;X. Zhang;Y. Yao;H. Liu
我们提出了计算的光学力的异质二聚体的两个金纳米棒头到尾对齐，平面波照明下，是沿沿着二聚体轴偏振。研究发现，在偶极-四极Fano共振附近，纳米棒之间的光学结合力发生反转，表明发生了吸引力到排斥力的转变。这与同二聚体相反，同二聚体在类似构型中不显示负结合力。此外，力谱的特点是不对称的线形，并相应地移动时，法诺共振通过改变纳米棒的长度或它们的间隙进行调谐。我们发现，力反转与强的相位之间的变化的杂交偶极和四极模附近的法诺倾角。数值结果可以用近场光镊演示，对研究等离子体中的“光学物质”有一定的参考价值。
We present calculations of the optical force on heterodimer of two gold nanorods aligned head-to-tail, under plane wave illumination that is polarized along the dimer axis. It is found that near the dipole-quadrupole Fano resonance, the optical binding force between the nanorods reverses, indicating an attractive to repulsive transition. This is in contrast to homodimer which in similar configuration shows no negative binding force. Moreover, the force spectrum features asymmetric line shape and shifts accordingly when the Fano resonance is tuned by varying the nanorods length or their gap. We show that the force reversal is associated with the strong phase variation between the hybridized dipole and quadrupole modes near the Fano dip. The numerical results may be demonstrated by a near-field optical tweezer and shall be useful for studying "optical matters" in plasmonics.