等离激元-激子的耦合杂化与量子相干特性研究

Plasmonics of metal nanostructures is a frontier of modern physics. The coherent coupling of plasmon and exciton is a key research topic in active plasmonic nanosystems. In this proposal, we will study coherent coupling effect of metallic plasmon and excitons in semiconductor quantum dots and laser dye molecules, mainly focus on quantum and coherence effects (such as Rabi splitting and Fano interferences) and dynamics of excitation energy transfer. Theoretically, we will study plasmon-induced entanglement and Dicke cooperative emissions (including supperradiance and subradiance) of semiconductors by using wave-function and FDTD numerical simulation, and reveal amplified stimulating emissions by using density matrix equations. Combining chemical and physical methods, we will grow and fabricate silver mono-crystal Fabry-Perot ring cavity and the hybrids of gold nanorod and CdSe quantum dots with high quality, and tune coherent coupling of plasmon-exciton by adjusting growth parameters. Furthermore, we will study the ultrafast dynamics and quantum coherence behaviours by using femtosecond laser, try to improve the quantum efficiency of light harvesting and nonlinear figure of merit, and find the applications in design of active plasmonic nanodevices.

金属纳米结构表面等离激元研究属于物理学前沿课题，等离激元-激子相干耦合是有源等离激元体系的核心研究内容。本项目拟开展金属等离激元与半导体量子点和激光染料分子两种激子体系相干耦合效应的研究，重点研究等离激元－激子强耦合导致的Rabi劈裂和Fano干涉等量子相干效应及其激发能量传递动力学行为。理论上用解析波函数方法结合时域有限差分法（FDTD）数值模拟研究等离激元诱导的多个半导体量子点的Dicke协同辐射（包括纠缠、超辐射和亚辐射），用粒子数运动方程研究耦合体系中的受激放大辐射。实验上生长制备高质量银单晶Fabry-Perot 环形腔和Au纳米棒－CdSe量子点复合纳米结构，调节结构参数实现等离激元和激子的共振相干强耦合，并对量子等离激元进行探索性研究。采用飞秒激光探测等离激元－激子耦合超快动力学和量子相干特性，提高其光俘获量子效率和非线性品质因子，为有源等离激元纳米光学器件的设计提供依据。

等离激元-激子强耦合相互作用是目前等离激元体系的前沿热点课题，本项目围绕金属等离激元与半导体和染料分子等激子体系相干耦合效应，开展了以下研究工作：1）发展了可控生长技术，实验上制备了金属-金属、金属-硫化物、金属-稀土纳米晶体、金属-染料等多种等离激元异质纳米结构。2）观测到等离激元-激子Fano共振的非线性效应，并揭示其超快动力学行为和非线性增强机理。在理论上展示了磁Fano共振对二次谐波增强的巨大影响，并且探索了其增强的原理。3）用化学刻蚀方法制备得到从经典尺寸到量子尺寸的金纳米颗粒，结合理论计算分析，揭示等离激元的量子尺寸效应。4）利用等离激元-激子耦合相互作用和量子等离激元实现了对光催化效应的有效增强。5）通过半导体量子点与金属等离激元微腔相互耦合的结构参数优化，实现等离激元微腔与半导体量子点激子的相干耦合、等离激元相位调节、以及单个等离激元的传输。