光学天线共振耦合特性研究

发布时间：2018-04-16 10:33

本文选题：金属纳米颗粒 + 局域表面等离子体共振　；参考：《中国科学技术大学》2014年博士论文

【摘要】：光学天线能够实现局域光频电磁能量与远场传播光场能量之间的高效、定向性转换。由于金属局域表面等离激元共振的影响,光学天线在近场能量馈入,工作波长以及耦合方式等方面与微波天线有很大不同。基于这些特点,光学天线在增强分子荧光辐射,纳米尺度光束方向调制,突破衍射极限的光学成像等方面表现出优异的性质,被认为是现代光学发展的重要方向之一。本论文针对光学天线体系中共振耦合特性进行研究分析,重点开展了天线结构对于荧光分子发光增强,荧光分子辐射方向控制,类量子效应等方面的研究。本论文主要研究成果如下： 1.研究了荧光分子与不同光学天线结构相互耦合的荧光增强,以及辐射方向的调控,设计了超小型耦合金属棒纳米光学天线,在荧光分子激发和辐射波长具有局域等离子体双共振特性,并进一步探讨了其对荧光分子激发和辐射方向性的影响,以及组阵天线结构对天线方向性的增强特性。 2.基于并矢格林函数理论方法,系统研究了不同偏振的偶极子点源与不同材料的半无限大介面相互作用的机理过程,分析了水平和垂直方向偶极子场对称性不同对于辐射效应的影响,并基于此设计了一种可主动调控辐射方向的光学天线结构。 3.通过对圆偏振偶极子角谱特性研究,发现该偏振的偶极子能够很好地单向激发导波模式,基于此设计了一种产生涡旋场的简单光学天线,其作用与圆偏振偶极子类似,可有效地用以激发高定向性的导波模式。 4.利用金属光学天线结构中的明、暗模式相互叠加,数值分析研究了T型纳米颗粒中的Fano共振效应,并通过谐振子模型给出了对应解释。研究了不同耦合点对应的模式耦合强度的区别,发现了T型耦合结构具有更大的耦合强度,同时这种构型对光谱和位置信息都可以提供更高的折射率传感灵敏度。 5.使用数值算法研究了表面等离子体法珀腔模和局域纳米线磁模式的强耦合过程,并与经典原子-腔强耦合体系中的极子模型(Polariton Model)获得的结果一致。利用这种结构得到了845倍的局域磁场增强和280meV的Rabi分裂。本论文的创新点和特色： 1.提出了基于调制偶极子偏振特性的纳米尺度光束操控结构。通过改变圆偏振偶极子和金属衬底之间的相互距离,可以获得单向性较好并且辐射方向可调的远场出射光；通过构造合适的纳米天线结构,模拟圆偏振偶极子的作用,实现定向激发导波模式。 2.设计了一种可用于荧光分子探测的双共振光学天线结构。该天线的两个共振峰可通过改变天线结构尺寸独立调节,以适应不同荧光分子的激发和辐射能级。同时,该结构也可对荧光分子激发光和辐射光的远场方向进行独立调节,空间上将激发光散射噪声和荧光分子辐射的信号有效分离,可用于高性噪比的荧光探测。 3.基于光学天线模式特点与原子能级结构的相似性,数值上通过设计相应光学天线结构实现了Fano共振和强耦合这两种量子效应。提出了一种对光谱和位置信息都敏感的局域折射率传感方法。获得了280meV的Rabi分裂。为传统的量子效应提供了光学天线这一新的研究平台。
[Abstract]:Optical antenna can achieve between local optical frequency electromagnetic energy and far-field optical field propagation energy efficient, directional conversion. Due to the influence of metal localized surface plasmon resonance, optical antenna in near field energy feed, working wavelength and coupling modes are very different with the microwave antenna. Based on these characteristics, optical antenna the enhanced fluorescence radiation, beam direction of nano scale modulation, optical imaging and other aspects beyond the diffraction limit exhibit excellent properties, is considered to be one of the important direction of the development of modern optics. This paper analyses the coupling characteristics of resonant optical antenna system, focusing on the antenna structure for fluorescence emission enhancement, fluorescence control molecular radiation research, quantum effects and so on.
In this paper, the main research results are as follows:
1. of the fluorescent molecules with different fluorescence optical antenna structure coupling enhancement, and the regulation of radiation, the ultra small metal rod coupling optical nano antenna design, as fluorescence excitation and radiation wavelength with local plasma double resonance characteristics, and further discusses its influence on the fluorescence excitation and radiation direction, and antenna array structure to enhance antenna directivity.
2. based on the theory and the dyadic Green function method, systematically studies the mechanism of semi infinite interface dipole interacting point source with different polarizations with different materials, analyzes the horizontal and vertical dipole field symmetry has different effects on the radiation effect, and design an active control radiation optical antenna structure based on this.
3. through the study of spectral characteristics of circularly polarized dipole dipole polarization angle, found the good unidirectional excitation of guided wave mode, based on the design of a simple optical antenna to form a vortex field, its function and the circular polarization dipole is similar, can be used to stimulate highly directional guided wave mode.
4. the use of metal optical antenna structure in the Ming Dynasty, dark mode superposition, numerical analysis of Fano type resonance of T nanoparticles, and the oscillator model gives the corresponding explanation. The difference of the mode coupling strength corresponding to different coupling point, found the T type coupling structure has larger coupling intensity at the same time, the configuration of the spectrum and the location information can provide the higher refractive index sensing sensitivity.
5. the use of strong coupling numerical algorithm on surface plasmon F-P cavity mode and local mode of magnetic nanowires, and dipole model and classical atom cavity coupling in the system (Polariton Model) consistent with the results obtained by using this structure. Local magnetic field 845 times enhancement and 280meV Rabi division.
The characteristics and innovation of this paper:
1. the polarization characteristics of modulation dipole nano scale beam control structure based on. By changing the distance between the circular polarization dipole and the metal substrate, can obtain better light radiation and one-way direction adjustable far field; by constructing appropriate nano antenna structure, simulation of circular polarization dipole, directional excitation the guided wave mode.
2. can be used to design a double resonance optical antenna structure fluorescence detection. The two resonant peaks of the antenna by changing the antenna size independent regulation, in order to adapt to the different fluorescence excitation and radiation level. At the same time, the structure can also be of far field fluorescence excitation light and radiation are independent regulation, effective separation of signal space will stimulate light scattering noise and fluorescence, fluorescence can be used for high SNR detection.
3. based on the similarity of the optical antenna pattern characteristics and the structure of atom, numerically by designing the corresponding optical antenna structure of the Fano resonance and strong coupling of these two kinds of quantum effects. A local index is sensitive to spectral and location information rate sensing method was 280meV. Rabi provides the optical antenna division. This is a new research platform for traditional quantum effects.

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN820

【共引文献】