【作者】 邓燕；

【导师】 明海； 王沛；

【作者基本信息】 中国科学技术大学 ， 光学， 2008， 博士

【摘要】 探索性能优良的三阶非线性光学材料、新型结构以及三阶非线性光学性质的研究一直是非常活跃的前沿课题。光与纳米金属复合结构相互作用产生的新现象和实现的新功能,在微纳传感探测、纳米光子器件及其集成等纳米光子学领域具有良好的应用前景。本论文的研究工作是以发展非线性表面等离子体光子器件为目标,基于近场光学和非线性光学,采用有效介质理论、退耦近似等理论研究了纳米金属复合结构中新颖的光学现象,利用纳米金属复合结构增强了光学非线性效应,进行了ATR结构的全光调制研究。本论文的研究工作和成果如下:1.利用离散偶极子近似方法研究了不同形状纳米金属颗粒的光学性质;分析了不同尺寸、不同长径比、不同周围介质环境等因素对球形银颗粒和金纳米棒消失谱(散射谱+吸收谱)的影响,给出了近场区域的场分布图;从单个颗粒拓展到多个颗粒体系,利用耦合偶极子方法初步分析了多个金属颗粒之间的相互作用,为实验工作提供了良好的理论依据。2.利用退耦近似方法,研究不同体积分数尤其是体积分数高的纳米金属球形颗粒复合介质膜中的线性光学性质和有效非线性光学性质;结合谱表示法和Maxwell-Garnett理论分析了不同结构参数对纳米金属颗粒复合介质光学双稳特性的影响;结合模场理论和数值方法分析了在激发表面等离子体的情况下纳米金属-非线性介质多层膜结构的光学非线性增强特性,为实现光学双稳、光开关等全光器件奠定了良好的理论基础。3.通过引入可逆加成-裂解链转移法与纳米粒子原位还原的方法,制备了具有高浓度、分散均匀的纳米银颗粒复合聚合物材料;利用Z扫描方法研究了不同银颗粒浓度、不同复合体系等因素对纳米银溶胶、掺杂纳米银颗粒的AZO/PMMA薄膜和掺杂纳米银颗粒的R6G/PMMA薄膜的三阶非线性光学性质的影响;实验结果表明纳米银颗粒的加入可以有效调节纳米金属复合材料的线性和非线性光学性质,在新型光子器件设计应用方面具有广阔的前景。4.研究了基于衰减全内反射(ATR)结构的偶氮聚合物全光调制实验,与传统偶氮聚合物光致双折射效应的全光调制实验相比,具有调制时间快、调制幅度大和调制对比度高等优点;提出了一种基于表面等离子体局域增强的高灵敏的全光调制方案,对发展设计基于表面等离子体的新型全光调制元件具有很好的指导意义。本论文的创新点主要包括:1.利用离散偶极子近似方法和耦合偶极子方法研究了单个纳米金属颗粒和多个纳米金属颗粒体系的光学性质,分析了形状、尺寸、长径比和周围介质环境等因素对颗粒消失谱和近场分布的影响。2.从无序结构拓展到有序多层膜结构的光学非线性增强特性研究,分析了不同体积分数尤其是体积分数高的无序纳米金属颗粒复合介质的三阶非线性光学响应;研究了在激发表面等离子体的情况下有序纳米金属-非线性介质复合多层膜结构的光学非线性增强特性,对于有序多层膜结构的实际应用具有一定的指导意义。3.采用一种新的制备方法,合成高浓度、均匀分散的纳米银颗粒复合聚合物材料,研究了不同银颗粒浓度、不同复合体系等因素对纳米银复合聚合物材料三阶非线性光学性质的影响;实验结果表明纳米银颗粒可以有效的调节复合材料的线性和三阶非线性光学性质,在发展制作新型光子器件方面具有很好的应用前景。4.实现了基于ATR结构的偶氮聚合物全光调制实验,与传统偶氮聚合物全光调制实验相比调制效果明显提高;设计了一种基于表面等离子体局域增强的高灵敏性全光调制方案,理论分析的结果对于设计新型全光器件具有一定的借鉴意义。更多还原

【Abstract】 Probing into the excellent third-order nonlinear optical materials, new structure and researching third-order nonlinear optical properties are all along a very actively advancing task. The interactions of the light and metal composite nanostructures generate new phenomena and realize new function, which has potential applications in the nano-optics field. The main works aim at the development of nonlinear surface plasmon photonic devices on the basis of near-field optics and nonlinear optics, and involve the research of metal composite nanostructures’ novel optical phenomena by the effective medium theory and the decoupling approximation, the enhanced optical nonlinearity of metal composite nanostructures and the all-optical modulation based on ATR structure. The main research works and conclusions are as following:1. Optical properties of different shape metal nanoparticles are simulated by the discrete dipole approximation (DDA) method. The effects of the size, the ratio of long-short axes, the surrounding medium on the extinction spectra of spherical silver nanoparticle and gold nanorod are analyzed and the near-field distributions are shown. From the single nanoparticle to multi-nanoparticles system, the coupled dipoles equation method is used to analyze the interaction of many metal nanoparticles, providing well theoretical thought for the experiment.2. Linear optical properties and the effective nonlinear optical properties of metal nanoparticle composites with different volume fraction are investigated by the decoupling approximation. Combining the spectral representation and the Maxwell-Garnett method is to analyze the influence of different structure parameters on the optical bistability of metal nanoparticle composites. The enhanced optical nonlinearity of metal-nonlinear medium multilayer structure under the excitation of surface plasmon polariton is analyzed by the model-field theory and the numerical method, which lay a good foundation of the theory for the realization of all-optical devices.3. A new preparation is used for high concentration and well-dispersion silver nanoparticle polymer composites, which is the combination of Reversible Addition-fragmentation Transfer method and the in-situ reduction, simultaneously. Utilizing the Z-scan experimental setup, the influences of various silver concentration and different matrix composites on the third-order nonlinear optical effects of silver colloidal solutions, Ag nanoparticle doped azo polymer films and Ag nanoparticle doped R6G/PMMA film are investigated. The experimental results demonstrate the addition of Ag nanoparticles can effectively modulate the linear and nonlinear optical properties of metal nanoparticle composites, which is important to the application of new photonic devices.4. All-optical modulations based on ATR structure of azo polymer are investigated, which possess the quicker modulation time, the bigger modulation range and the higher modulation contrast in comparison with the traditional azo polymer one. A new sensitive all-optical modulation project on surface plasmon is proposed, which is very instructive for the new type all-optical modulation.Highlights of the dissertation are as following:1. Optical properties of single nanoparticle and multi-nanoparticles system are investigated by DDA method and the coupled dipoles equation method. The effects of the shape, the size, the ratio of long-short axes, the surrounding medium on the extinction spectra and the near-field distribution are analyzed.2. The enhanced optical nonlinearities are investigated from the random structures to the ordered structures. The effective nonlinear optical properties of metal nanoparticle composites with different volume fraction are investigated by the decoupling approximation. The enhanced optical nonlinearity of metal-nonlinear medium multilayer structure under the excitation of surface plasmon is analyzed, which is beneficial to the application of the multilayer structure.3. A new preparation is used for high concentration and well-dispersion of silver nanoparticle polymer composites. Utilizing the Z-scan experimental setup, the influences of various silver concentration and different composites on the third-order nonlinear optical effects of silver nanoparticle polymer composites are investigated. The experimental results demonstrate the addition of Ag nanoparticles can effectively modulate the linear and nonlinear optical properties of the composites, which is important to the application of new photonic devices.4. All-optical modulations of azo polymer based on ATR structure are realized, which possess the improved modulation effects in comparison with the traditional azo polymer one. A new sensitive all-optical modulator project on surface plasmon polariton is numerical designed. The theoretically analyses possess the instructive meaning for designing new type all-optical devices.更多还原