The interaction between plasmons in metal nanostructures and excitons in layered materials attracts recent interests due to its fascinating properties inherited from the two constituents, e.g., the high tunability on its spectral or spatial properties from the plasmonic component, and the large optical nonlinearity or light emitting properties from the excitonic counterpart. Here, we demonstrate light-emitting plexcitons from the coupling between the neutral excitons in monolayer WSe₂ and highly confined nanocavity plasmons in the nanocube–over−mirror system. We observe, simultaneously, an anticrossing dispersion curve of the hybrid system in the dark-field scattering spectrum and a 1700 times enhancement in the photoluminescence. We attribute the large photoluminescence enhancement to the increased local density of states by both the plasmonic and excitonic constituents in the intermediate coupling regime. In addition, increasing the confinement of the hybrid systems is achieved by shrinking down the size of the hot spot within the gap between the nanocube and the metal film. Numerical calculations reproduce the experimental observations and provide the effective number of excitons taking part in the interaction. This highly compact system provides a room temperature testing platform for quantum cavity electromagnetics at the deep subwavelength scale.

中文翻译：

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发光的激态：在中间耦合体系中利用等离激子相互作用。

金属纳米结构中的等离激元与层状材料中的激子之间的相互作用吸引了人们的兴趣，这是因为它具有两种成分所具有的引人入胜的特性，例如，等离激元成分在光谱或空间特性上具有很高的可调谐性，以及较大的光学非线性或光从激子对应物释放出特性。在这里，我们从单层WSe _2中的中性激子之间的耦合中展示了发光的plexcitons。纳米立方镜面系统中的高度受限的纳米腔等离激元。我们同时在暗场散射光谱中观察到了杂化系统的反交叉色散曲线，并在光致发光方面增强了1700倍。我们将大的光致发光增强归因于中间耦合机制中的等离激元和激子成分增加了态的局部密度。另外，通过减小纳米立方体和金属膜之间的间隙内的热点的尺寸来实现增加混合系统的限制。数值计算重现了实验观察结果，并提供了参与相互作用的激子的有效数量。