Nanophotonics and Metrology Laboratory (NAM), Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
Nano Lett. 2013 Apr 10;13(4):1787-92. doi: 10.1021/nl400393e. Epub 2013 Mar 6.
Second harmonic generation from plasmonic nanoantennas is investigated numerically using a surface integral formulation for the calculation of both the fundamental and the second harmonic electric field. The comparison between a realistic and an idealized gold nanoantenna shows that second harmonic generation is extremely sensitive to asymmetry in the nanostructure shape even in cases where the linear response is barely modified. Interestingly, minute geometry asymmetry and surface roughness are clearly revealed by far-field analysis, demonstrating that second harmonic generation is a promising tool for the sensitive optical characterization of plasmonic nanostructures. Furthermore, defects located where the linear field is strong (e.g., in the antenna gap) do not necessarily have the strongest impact on the second harmonic signal.
采用表面积分公式对等离子体纳米天线的二次谐波产生进行数值研究，以计算基波和二次谐波电场。真实金纳米天线与理想化金纳米天线的比较表明，即使在线性响应几乎没有改变的情况下，二次谐波产生对纳米结构形状的不对称性也非常敏感。有趣的是，远场分析清楚地揭示了微小的几何不对称性和表面粗糙度，证明了二次谐波产生是一种有前途的工具，可用于对等离子体纳米结构进行灵敏的光学特性分析。此外，位于线性场较强的位置（例如，在天线间隙中）的缺陷不一定对二次谐波信号产生最强的影响。
