Exciton-plasmon interaction in metal-semiconductor hybrid nanostructures

该项目旨在提高对由金属和半导体或分子组成的典型混合纳米结构的线性和非线性光学激发的微观理解，特别是在所有三个空间维度上具有纳米扩展的系统中。我们建议特别研究激子(X)，半导体的基本光激发和表面等离子体（SP）极化子（SPP），金属纳米结构的基本光激发之间的相干耦合。相干超快光谱和纳米光学成像技术的实验方法将与多体理论、量子化学和无序物理的理论建模方法以及光学和电子性质的计算机模拟相结合。我们将使用这些工具在纳米-飞秒尺度上研究SPP场与活性量子材料在增益区耦合的动力学。有机激光染料如罗丹明和无机胶体量子点将被用作增益介质。为了增加和优化激子-等离子体耦合，我们将探索几种途径来尽可能地限制SPP场的空间，使我们能够将SPP场强耦合到单个低能级量子发射器上。在第一个资助期内展示的所谓的耦合X-SPP量子模式的Rabi分裂的超快操纵为探索这种混合系统中的强耦合甚至超强耦合机制开辟了未知的途径。我们的目标是展示新的超快功能，可用于未来的等离子体和量子等离子体器件，如等离子体晶体管或纳米天线增强的单纳米颗粒传感。特别感兴趣的是(i)活性材料和增益机制的物理特性，(b)单量子发射体，量子等离子体和纳米-飞秒尺度上的光开关，以及(c)无序诱导的局域化和具有极端局域场增强的热点形成的相互作用。

The project aims at an improved microscopic understanding of the linear and nonlinear optical excitations of prototypical hybrid nanostructures comprising metal and semiconductors or molecules, specificially in systems with nanometer extension in all three spatial dimensions. We propose to investigate in particular the coherent coupling between excitons (X), the elementary optical excitations of semiconductors, and surface-plasmon (SP) polaritons (SPP), the elementary optical excitations of metallic nanostructures. Experimental methods from coherent ultrafast spectroscopy and nano-optical imaging techniques will be combined with theoretical modeling using methods from many-body theory, quantum chemistry and disorder physics as well as computer simulations of optical and electronic properties. We will use these tools to study the dynamics of SPP fields coupled to active quantum materials in the gain regime on a nanometer-femtosecond scale. Organic laser dyes such as rhodamines and inorganic colloidal quantum dots will be used as gain media. Several routes will be explored to confine the SPP field spatially as much as possible in order to increase and optimize the exciton-plasmon coupling, enabling us to strongly couple SPP fields to individual few-level quantum emitters. The ultrafast manipulation of the so-called Rabi splitting of the coupled X-SPP quantum modes demonstrated within the first funding period opens up uncharted avenues for exploring the strong- or even ultrastrong-coupling regime in such hybrid systems. We aim at demonstrating new ultrafast functionality, exploitable in future plasmonic and quantum-plasmonic devices such as plasmonic transistors or for nanoantenna-enhanced sensing of single nanoparticles. Of particular interest are (i) active materials and the physics of the gain regime, (b) single quantum emitters, quantum plasmonics, and light switching on the nanometer-femtosecond scale, as well as (c) the interplay of disorder-induced localization and the formation of hot spots with extreme local field enhancement.