[论文解读] Ultrastrong Light-Matter Coupling in 2D Metal-Chalcogenates

Surendra B. Anantharaman, Jason Lynch+11 more|arXiv (Cornell University)|Aug 22, 2023

Strong Light-Matter Interactions被引用 4

一句话总结

本研究在二维金属硫属化合物（MOCHA）晶体，特别是硫钼酸盐（mithrene）中实现了超强光-物质耦合，由于强激子振子强度和高折射率，其Rabi劈裂在室温下超过600 meV。该体系表现出明亮的极化子发射，并在密闭法布里-珀罗腔中实现约1 nm的线宽压缩，确立了MOCHA材料在深蓝-绿光极化子学中的巨大潜力。

ABSTRACT

Hybridization of excitons with photons to form hybrid quasiparticles, exciton-polaritons (EPs), has been widely investigated in a range of semiconductor material systems coupled to photonic cavities. Self-hybridization occurs when the semiconductor itself can serve as the photonic cavity medium resulting in strongly-coupled EPs with Rabi splitting energies > 200 meV at room temperatures which recently were observed in layered two-dimensional (2D) excitonic materials. Here, we report an extreme version of this phenomenon, an ultrastrong EP coupling, in a nascent, 2D excitonic system, the metal organic chalcogenate (MOCHA) compound named mithrene. The resulting self-hybridized EPs in mithrene crystals placed on Au substrates show Rabi Splitting in the ultrastrong coupling range (> 600 meV) due to the strong oscillator strength of the excitons concurrent with the large refractive indices of mithrene. We further show bright EP emission at room temperature as well as EP dispersions at low-temperatures. Importantly, we find lower EP emission linewidth narrowing to ~1 nm when mithrene crystals are placed in closed Fabry-Perot cavities. Our results suggest that MOCHA materials are ideal for polaritonics in the deep green-blue part of the spectrum where strong excitonic materials with large optical constants are notably scarce.

研究动机与目标

• 探索新兴的二维金属硫属化合物（MOCHA）材料，特别是硫钼酸盐（mithrene）中的超强光-物质耦合。
• 解决在深蓝-绿光谱范围内强激子材料与大光学常数材料稀缺的问题。
• 展示具有高Rabi劈裂和明亮发射的自杂化激子-极化子在室温下的实现。
• 研究基于硫钼酸盐的异质结构中极化子色散与线宽工程。

提出的方法

• 在金基底上制备单层硫钼酸盐晶体，以实现激子与腔模的自杂化。
• 通过光致发光光谱测量Rabi劈裂，以量化光-物质耦合强度。
• 使用密闭法布里-珀罗腔限制光场，增强极化子质量，减小发射线宽。
• 低温测量以探测极化子色散关系及多体效应。
• 分析光学常数与激子振子强度，以解释超强耦合机制。

实验结果

研究问题

• RQ1 能否在二维金属硫属化合物体系（如硫钼酸盐）中实现超强光-物质耦合（Rabi劈裂 > 600 meV）？
• RQ2 硫钼酸盐的高折射率与强振子强度在实现超强耦合中起到何种作用？
• RQ3 能否在MOCHA基异质结构中实现明亮的、室温下的极化子发射？
• RQ4 腔体限制如何影响硫钼酸盐中极化子的线宽与发射质量？
• RQ5 在低温下，硫钼酸盐中的极化子色散具有何种特性？

主要发现

• 硫钼酸盐中的Rabi劈裂超过600 meV，表明该体系处于超强耦合区域。
• 由于强振子强度与高折射率，室温下观察到明亮的激子-极化子发射。
• 在密闭法布里-珀罗腔中，极化子发射线宽压缩至约1 nm。
• 低温测量揭示了清晰的极化子色散关系。
• 硫钼酸盐中强激子响应与高光学常数的结合，实现了无需外部腔体的高效自杂化。