二维原子晶体材料异质结中超快室温极化激元机理研究

Monolayer transition metal dichalcogenides are ideal two-dimensional (2D) atomic crystal materials for the investigation of strong light-matter interactions and exciton-polaritons at room temperatures. As half-light half-matter quasi-particles, exciton-polaritons provides a directional and controllable photoluminescence emission mode based on spin-valley selectivity, opening up new possibilities for light emitting devices on chip. Being oriented to the applications in the novel on-chip light sources with directional emission and controllability, this project focuses on clarifying the exciton-polariton mechanism in 2D TMDCs-Photonic crystal (PhC) heterostructures and exploring the manipulation approaches. The main contents include: (1) Establishing theoretical model and numerical simulation of coupling effect between two-dimensional atomic crystal and photonic crystal, and designing 2D atomic crystal materials based heterojunctions under strong coupling; (2) Investigation of exciton-polariton characteristics in the monolayer-TMDCs based heterostructures at multiple levels, via ultra-fast time and angle-resolved spectroscopy measurement technology and micro-nanofabrication technology, along with the construction of optimized ultrafast dynamics model for exciton-polaritons. (3) The effective approaches to precisely control the polariton characteristics in the monolayer-TMDCs based heterojunction. This project provides a theoretical and experimental basis for the practical application of 2D atomic crystal materials based heterostructures in new on-chip light sources.

单层过渡金属硫化物是研究光与物质强相互作用和室温激子-极化激元的理想二维原子晶体材料。激子-极化激元作为半光半物质的准粒子，能够提供一种基于能谷选择性的定向且可控地荧光发射方式，为片上光源的研发提供了新思路。本项目以新型片上光源的应用为导向，对单层过渡金属硫化物-光子晶体异质结中激子-极化激元机理展开研究并探索调控方式，主要内容包括：(1)建立二维原子晶体材料与光子晶体强弱耦合效应的理论模型与数值模拟，设计强耦合作用下的二维材料异质结；(2)采用超快时间、角度分辨光谱测量技术和微纳加工技术，多层次开展新型异质结中激子-极化激元特性的研究，建立较为完善的二维材料异质结中极化激元的超快动力学模型；(3)探寻精确调控二维材料异质结极化激元特性的有效方式。本研究的预期成果将为二维材料异质结在新型片上光源中的应用走向实用化提供理论和实验基础。

基于二维原子晶体材料的强耦合腔激子极化激元器件在最近的科学研究中展示出了非常多有趣的宏观量子效应和新奇光电应用，比如玻色爱因斯坦凝聚、低阈值极化激元激光器、以及单光子超快开关等。然而，其内在物理过程尚不清晰阻碍了极化激元器件的实用化应用。本项目采用角分辨反射谱技术与瞬态显微反射谱技术相结合的测试方法，研究了二维原子晶体光子晶体异质结构中光生载流子特性对光与物质相互作用强度的影响，揭示了极化激元器件在不同光照条件下的超快动力学过程；具体分析了载流子数目与种类两个物理因素对激子-光子间耦合强度的调控作用，发现了自由电荷载流子引诱产生的超快光致库仑屏蔽效应能够有效减弱光与物质间相互作用强度；通过分析建立了强耦合极化激元器件耦合强度变化的物理模型，并借助精细的变激发波长实验对模型的有效性进行了验证；最终形成提出了一种全新的耦合强度全光调控方案，为极化激元器件在低功耗纳米光电子器件上的应用提供理论和实验基础。