【作者】 吴腾飞；

【导师】 李醒飞；

【作者基本信息】 天津大学 ， 仪器科学与技术， 2013， 博士

【摘要】 非对称等离激元纳米结构具有显著的局域电磁场增强特性、等离激元Fano共振效应及光学各向异性等独特的光学性能，不仅可用于开发具有单分子探测能力的超高灵敏度等离激元光学传感器件，还可用于开发新型的纳米光子器件。因此，本文针对非对称等离激元纳米结构，根据数值仿真结果研究对称性破缺效应，建立等离激元杂交模型，研究Fano共振效应以及光学各向异性，制造金半壳阵列传感基片并确定LSPR峰值传感特性。首先，建立半壳结构的等离激元共振模型，应用等离激元杂交理论解释半壳结构等离激元共振的激发、移动以及分裂。研究发现环状尖端的尖锐特征是引起半壳结构局域电磁场增强的主要因素，而结构内部等离激元耦合进一步增强了局域电磁场。由于等离激元共振模式的可调节性和局域电磁场的增强，半壳结构可在LSPR峰值传感和表面增强光谱中开发为一种高效的传感基底。其次，基于等离激元杂交理论研究核-半壳结构Fano共振效应的激发机理。数值计算结果表明“暗”模式的激发及与“明”模式的交互是激发等离激元Fano共振的原因。研究结果表明等离激元纳米结构对称性破缺显著影响Fano共振，通过改变金半壳对称性破缺程度和金核偏移量，可以实现Fano共振的高度可调节性。金半壳与金核之间的等离激元交互作用导致局域电磁场的极大增强，使其在生物传感中具有潜在的应用价值。然后，研究金叠壳结构的二维光学各向异性，基于“球状空腔-椭球体”等离激元杂交模型合理地解释叠壳结构的二维光学各向异性。相对于半壳结构，叠壳结构进一步破坏了金属壳的旋转对称性，因此激发横向、轴向和纵向三种不同的等离激元共振模式。可调节的LSPR共振模式，局域电磁场增强和各向异性的光学特性显示叠壳结构在表面增强光谱和显示设备的“智能”涂层材料中存在着潜在应用。最后，通过浸涂和离子溅射的方法，制造开口朝下的金半壳阵列传感基片。使用不同折射率的试剂测量不同金壳厚度的传感基片的折射率灵敏度，基于层层沉积方法研究不同厚度金壳的传感基片的探测距离。更多还原

【Abstract】 The asymmetric plasmonic nanostructures can support a series of unique opticalphenomena, such as significant local electromagnetic field enhancement, plasmonicFano resonances and anisotropic optical response. These optical characteristics notonly are used to develop ultra-sensitive single molecule sensing substrates, but alsoapplied in various novel nanophotonic devices. This paper focused on the asymmetriccore-shell plasmonic nanostructures to study the plasmn hybridization effect and thesymmetry breaking by using numerial methods. Moreover, the plasmonic Fanoresonances and anisotropic optical responses are investigated. The Au semishellssensors have been fabricated to measuring the LSPR sensing characteristics.Firstly, the plasmon resonances model was built for semishells. The plasmonhybridization theory is applied to interpret the excitation, shift and slitting of theplasmon resonances of semishells. The calculation results show that the sharp featuresat the ring-tip is the main reason for local field enhancement in semishells. Theintra-particle coupling further enhances the local field. For the tunable plasmon modesand local field enhancement, the semishells can be developed as powerful sensingsubstrates in application of LSPR wavelength-shift sensing and surface-enhancedspectroscopy.Secondly, we used the plasmon hybridization theory to investigate the origin ofthe Fano resonance in core-semishells. The calculation results show that theinteraction between “bright” and “dark” plasmon modes is responsible for theexcitation of Fano resonances. The symmetry breaking of plasmonic nanostructuressignificantly influences the Fano resonance. The tenability of Fano resonances can beaccieved by changing the degree of symmetry breaking in semishell and displacementof the core with respect to the semishell. The local field enhancement induced byplasmon hybridization between the Au core and semishell provides the potentialapplications in biological sensing.Then, we studied the two-dimensional anisotropic optical response of overlappednaoshells. The cavity-ellipsoid model properly explains the unique optical propertiesof the overlapped nanoshells. For the breaking of rotational symmetry, the overlappednanoshells can excite transverse, axial, and longitudinal plasmon resonance modes. The tunable plasmon resonances, the enhanced local fields and the anisotropic opticalproperties suggest that the overlapped nanoshells have potential applications insurface-enhanced spectroscopy and “smart” coating in windows or display devices.Finally, The Au semishell sensing substrates were fabricated by dip coating andion sputtering. The refractive index sensitivity of semishells with different Au shellthicknesses is measured by using solution of different refractive index. The detectionlimit of the sensing substrates is investigated by the layer-by-layer depositon.更多还原