二维材料异质结与贵金属纳米腔的多模强耦合特性研究

Strong coupling between cavity and materials has important applications in monatomic laser, quantum information processing and other fields. Compared with the single Rabi splitting caused by the coupling of a kind of exciton and a cavity mode, multimode strong coupling achieved by the interaction between multiple excitons and the single cavity mode has unique advantages in terms of multimode sensing and energy transfer between multi-energy states. Due to the large transition dipole moment, monolayer transition metal dichalcogenides has attracted great attentions in studying strong coupling. However, only one study has reported the multimode strong coupling based on tungsten disulfide at low temperature. In this project, a new scheme of multimode strong coupling of two-dimensional heterostructures and noble metal nanocavity composite structure is proposed. Two kinds of excitons from two-dimensional heterostructures interact with the surface plasmons of ultrasmall mode volume at the same time, which is expected to realize double Rabi splitting at room temperature. Under multimode strong coupling system, we focus on the influence of hybrid states on the process of interlayer charge transfer of heterostructures and regulating the rate of charge transfer. Furthermore, it reveals the new mechanism of interlayer coupling of heterostructures. This study is beneficial to develop a new type of strong coupling system and provides an important basis for the practical application of strong coupling.

谐振腔与物质的强耦合在单原子激光、量子信息处理等领域有重要应用。相比广泛研究的单一激子与腔模耦合形成的单重拉比劈裂，多种激子与同一腔模相互作用实现的多模强耦合在多模传感、多能态间能量传递等方面具有独特优势。单层过渡金属二硫族化合物由于具有极大的跃迁偶极矩成为实现强耦合的研究热点，然而目前仅一项研究报道了低温下基于二硫化钨的多模强耦合。本项目提出二维异质结与贵金属纳米腔复合结构实现多模强耦合的新方案，二维异质结中两种激子同时与超小模式体积的等离激元相互作用，以期实现室温下双重拉比劈裂。并重点研究在多模强耦合体系下，杂化态对异质结层间电荷转移过程的影响，从而实现对电荷转移速率的调控，进一步揭示异质结层间耦合的新机理，将有利于发展一类新型强耦合体系，并为强耦合的实际应用提供重要依据。

激子-等离激元之间的强耦合相互作用为推动室温下产生和控制量子态策略提供了新方案，为单光子源以及量子信息处理的实现带来了新的研究机遇。本项目首先基于二维材料-金属纳腔的复合结构，研究了金属纳米颗粒的周围环境、颗粒尺寸对耦合强度的影响。通过将复合结构浸泡在二氯甲烷和乙醇的混合溶液中，耦合强度的范围从183meV连续调谐到273meV，相比空气中有近两倍的提高。通过引入光敏纳腔，实现了单一纳米颗粒下色散曲线的获取。在此基础上揭示了颗粒尺寸与耦合强度之间的线性关系。其次为了实现多模强耦合，将MoS2-WS2垂直异质结集成到间隙等离激元纳腔，暗场散射光谱中表现出双重拉比劈裂。利用多浓度亚甲基蓝染料分子与纳腔复合结构，实现了从单模到多模强耦合体系的建立。此外，在本项目的支持下，理论上提出了量子点-金属纳腔复合结构建立手性单光子源平台，利用纳米立方体-六方纳米板异质二聚体研究了多波段可调谐激子诱导透明。该课题研究成果拓展了多模强耦合体系，揭示了影响耦合强度的多种因素，为基于激子极化激元的光子器件的开发提供了理论指导。综上所述，我们解决了项目申请中提出的大部分关键问题，基本实现了既定的研究目标，并在相关领域进行拓展。本项目执行期间，共发表了标注该项目资助的SCI学术论文9篇，包括ACS Photonics，Nanophotonics， ACS Appl. Mat. Interfaces，Opt Express各1篇以及Nanoscale 2篇。