石墨烯-贵金属低维复合结构光学性质研究

By combining the physics of graphene and plasmonics, we perform the research on the optical properties of low dimensional hybrid structures of graphene, metallic nanostructure and quantum emitter. We explore the new optical characteristics related to the Dirac excitation with linear dispersion relation, and study the features and optical properties of new excitations due to the interaction among the individual excitations and collective excitations of different nature. Making use of the intrinsic modulation and external tailoring (doping, layer number control, the design of the size, shape of metallic nanoparticles and the structures of nanoparticle arrays), we study the interband transtion/intraband transition induced optical properties and the modulation of the local field beyond the diffraction limit. We analyze the competition among the coupling effect, local field enhancement effect and the dissipation effect. Based on the effective modulation of the local field, we study the tailoring of the optical process of the quantum emitters, paying special attention to the interference effect and nonlinear effect. We develop the modeling based on the self-consistent coupling theory and the theoretical methods combing the theory of density matrix and Green's function and the FDTD simulation. We propose the effective technique of local field modulation through the coupling among the substructures. Our work will deepen the understanding of the basic principle of light-matter interaction in low dimensional systems, and provide the bases for the design of functional devices based on low dimensional structures.

把石墨烯物理和等离激元光子学（plasmonics）相结合，研究由石墨烯、金属纳米结构、量子发射子(quantum emitter)构成的低维复合体系光学性质。探究与具有线性色散关系的Dirac型激发相联系的光学新特征，考察不同属性个体激发、集体激发相互作用导致新型激发元的特点及其光学表现；利用内禀调控和外部剪裁（石墨烯掺杂，层数、金属颗粒尺寸、形状，阵列结构等）手段，研究体系与带间激发和带内激发相联系光学性质的调节，及对突破衍射极限的局域场调控；分析耦合效应/局域场增强效应和耗散效应的竞争；研究基于局域场的有效调控，对量子发射子光学过程的调节，特别注重干涉效应、非线性效应；发展基于自洽场耦合的理论模型及密度矩阵、格林函数理论与FDTD模拟相结合的理论方法，提出通过子结构耦合调控局域场的有效手段。工作将深化人们对低维体系中光与物质相互作用规律的认识，并为基于低维结构的功能器件设计提供基础。

复合低维体系/结构因其受限效应/维度效应及子结构间相互作用引起丰富的物理效应，其光电性质调控研究具有重要科学意义及应用价值。本项目研究由石墨烯、金属纳米结构、分子等构成的低维复合体系/结构光电学性质调控及器件设计应用。探究了与具有线性色散关系的Dirac型激发相联系的光学、电学性质新特征，分析了耦合效应/局域场增强效应和耗散效应对复合体系光电性质的影响，考察了不同属性个体激发、集体激发相互作用导致新型激发元的特点及其光电性质表现；研究工作注重干涉效应、非线性效应、拓扑效应、强耦合效应、手征效应。研究工作发展了基于密度矩阵、格林函数理论与FDTD模拟相结合的理论建模与计算方法，得到系列创新性成果，指出通过内禀调控和外部剪裁（石墨烯层数、门电压、金属颗粒尺寸、形状，阵列结构等）手段实现光场调控；发现了复合结构非线性光电流响应新特征，揭示光生载流子和等离激元能量吸收调制的温度依赖载流子迁移率的竞争引起的光电流变号机理；指出通过石墨烯电子和离子束缚态(ion−electron bound states (IEBSs))解离和形成动力学调控光电流的机制，通过门电压、石墨烯层数可调控电子-离子束缚态的束缚能，从而调制光控电荷输运性质；揭示了复合结构非线性、手征光电响应特征，指出通过对称性（破缺）、空间构型、相互作用等调控光电响应的方法。工作深化了人们对低维体系中光与物质相互作用规律的认识，并为基于低维结构的功能器件设计提供基础。