Magnetic Plasmon-Enhanced Second-Harmonic Generation on Colloidal Gold Nanocups
Magnetic Plasmon-Enhanced Second-Harmonic Generation on Colloidal Gold Nanocups
复制标题
胶体金纳米杯上的磁等离子体增强二次谐波产生
DOI：
10.1021/acs.nanolett.9b00020
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发表时间：
2019-03-01
期刊：
影响因子：
10.8
通讯作者：
Lin, Hai-Qing
中科院分区：
文献类型：
--
作者：
Ding, Si-Jing;Zhang, Han;Lin, Hai-Qing
三维纳米结构的磁等离子体激元具有独特的光学响应，对光学纳米谐振器和纳米天线具有特殊的意义。在这项研究中，我们已经成功地合成了胶体Au和AuAg纳米杯，具有良好控制的非对称几何形状，可调的开口尺寸，和归一化的深度（h/B，其中h是深度，B是模板PbS纳米八面体的高度），可变的磁等离子体共振，以及大大增强的二次谐波产生（SHG）。当归一化深度h/B被调节到近似0.78 - 0.79时，实验观察到裸Au纳米杯的最有效的SHG。我们发现平均磁场增强在h/B = 0.65时达到最大，并揭示了最大的二次谐波可以归因于优化的磁等离子体共振和Au纳米杯的"避雷针效应"的共同作用.此外，我们首次证明了通过在Au纳米杯上过度生长Ag制备的AuAg异质纳米杯可以协同磁和电等离子体共振用于非线性增强。通过在基本激发波长和二次谐波波长处的双共振的定制，AuAg纳米杯的远场SHG强度比裸Au纳米杯的远场SHG强度增强21.8倍。这些发现为基于磁等离子体共振的非线性光学纳米天线的设计提供了一种策略，并且可以导致从纳米光子学到生物光谱学的各种应用。
The magnetic plasmons of three-dimensional nanostructures have unique optical responses and special significance for optical nanoresonators and nanoantennas. In this study, we have successfully synthesized colloidal Au and AuAg nanocups with a well-controlled asymmetric geometry, tunable opening sizes, and normalized depths (h/b, where h is depth and b is the height of the templating PbS nanooctahedrons), variable magnetic plasmon resonance, and largely enhanced second-harmonic generation (SHG). The most-efficient SHG of the bare Au nanocups is experimentally observed when the normalized depth h/b is adjusted to similar to 0.78-0.79. We find that the average magnetic field enhancement is maximized at h/b = similar to 0.65 and reveal that the maximal SHG can be attributed to the joint action of the optimized magnetic plasmon resonance and the "lightning-rod effect" of the Au nanocups. Furthermore, we demonstrate for the first time that the AuAg heteronanocups prepared by overgrowth of Ag on the Au nanocups can synergize the magnetic and electric plasmon resonances for nonlinear enhancement. By the tailoring of the dual resonances at the fundamental excitation and second-harmonic wavelengths, the far-field SHG intensity of the AuAg nanocups is enhanced 21.8-fold compared to that of the bare Au nanocups. These findings provide a strategy for the design of nonlinear optical nanoantennas based on magnetic plasmon resonances and can lead to diverse applications ranging from nanophotonics to biological spectroscopy.