金纳米棒复合结构中的双重法诺共振效应

Effect of the Double Fano Resonances in the Gold Nanorod Composite Structure

应用时域有限差分法(FDTD)模拟计算了由金纳米棒和偶极纳米天线构成的复合结构的消光光谱、近场增强和电荷分布。研究结果表明,在金纳米棒复合结构中能够产生双重法诺共振效应现象,并且在不同的法诺共振光谱位置处,能在不同的偶极纳米天线中产生很强的电磁场增强。此外,通过改变纳米棒复合结构中偶极纳米天线与金纳米棒的间距,以及偶极纳米天线中纳米棒的间距和长度大小,可以对法诺共振的调制深度和光谱位置进行大范围调谐。这些结果为理解金纳米棒复合结构中法诺共振效应的光学性质及纳米棒间的耦合作用提供了帮助,将金纳米棒复合结构用于微纳电子器件的优化设计,以满足其在光信息控制处理、多波段生物传感及表面增强喇曼散射等方面的应用。

The extinction spectrum,near-field enhancement and charge distributions of the composite structure composed of the gold nanorod and dipole nanoantennas were calculated by the finite-difference time-domain method（FDTD）.The research results show that the effect of double Fano resonances can generate in the gold nanorod composite structure.The electromagnetic field enhancements can produce in different dipole nanoantennas with different Fano resonances spectrum positions.In addition,the modulation depth and spectrum position of the Fano resonances can be largely tuned by modifying the spacing between dipole nanoantennas and gold nanorod in the nanorod composite structure,as well as the gap size and length of the nanorods in the dipole nanoantenna.These results will provide help for understanding the optical properties of Fano resonance effect and the coupling between the nanorods in the composite structure,and the gold nanorod composite structure can be used for the optimal design of the micro-nano electronic devices to meet the demands of applications in controlling and processing optical information,multiwavelength biosensor and surface-enhanced Raman scattering.