The transition metal dichalcogenides (TMDs) have drawn great research attention, motivated by the derived remarkable optoelectronic properties and the potentials for high-efficient excitonic devices. The plasmonic nanocavity, integrating deep-sub wavelength confinement of optical mode with dramatic localized field enhancement, provides a practical platform to manipulate light–matter interaction. In order to obtain strong exciton–plasmon coupling effects, it’s crucial to match the vibration direction of exciton to the available strong localized in-plane electric field. Herein, we demonstrate the coupling effect of in-plane exciton in monolayer tungsten diselenide (WSe2) to deterministic gap-plasmon field which is produced by nanometrically gapped collapsed nanofingers. The gap-plasmon field which is completely parallel to the in-plane excitons in WSe2 will drive a strong exciton–plasmon coupling at room temperature. More interestingly, it is experimentally observed that the luminescence of exciton–polariton cannot be influenced by the temperature in the range from 77 K to 300 K due to the presence of nanofingers. According to the theoretical analysis results, we attribute this finding to the dielectric screening effect arising from the extremely strong localized electric field of plasmonic nanofingers. This work proposes a feasible way to harness and manipulate the exciton of low-dimensional semiconductor, which might be potential for quantum optoelectronics.

中文翻译：

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由等离子体纳米指驱动的单层 WSe2 中面内激子-极化子的观察

过渡金属二硫属化物（TMDs）因其衍生的显着光电特性和高效激子器件的潜力而引起了广泛的研究关注。等离子体纳米腔将光学模式的深亚波长限制与显着的局部场增强相结合，为操纵光与物质的相互作用提供了一个实用的平台。为了获得强激子-等离子体耦合效应，将激子的振动方向与可用的强局域面内电场相匹配至关重要。在此，我们展示了面内激子在单层二硒化钨（WSe2) 到确定性间隙等离子体场，该场由纳米间隙折叠的纳米指产生。与 WSe 中的面内激子完全平行的间隙等离子体场2将在室温下驱动强激子 - 等离子体耦合。更有趣的是，实验观察到，由于纳米指的存在，激子-极化子的发光不受 77 K 至 300 K 范围内温度的影响。根据理论分析结果，我们将这一发现归因于由等离子体纳米指的极强局部电场引起的介电屏蔽效应。这项工作提出了一种利用和操纵低维半导体激子的可行方法，这可能是量子光电子学的潜力。