Plasmonic nanopatch antennas that incorporate dielectric gaps hundreds of picometers to several nanometers thick have drawn increasing attention over the past decade because they confine electromagnetic fields to grossly sub-diffraction-limited volumes. Substantial control over the optical properties of excitons and color centers confined within these plasmonic cavities has already been demonstrated with far-field optical spectroscopies, but near-field optical spectroscopies are essential for an improved understanding of the plasmon–emitter interaction at the nanoscale. Here, we characterize the intensity and phase-resolved plasmonic response of isolated nanopatch antennas by cathodoluminescence microscopy. Furthermore, we explore the distinction between optical and electron beam spectroscopies of coupled plasmon–exciton heterostructures to identify constraints and opportunities for future nanoscale characterization and control of hybrid nanophotonic structures. While we observe substantial Purcell enhancement in time-resolved photoluminescence spectroscopies, negligible Purcell enhancement is observed in cathodoluminescence spectroscopies of hybrid nanophotonic structures. The substantial differences in measured Purcell enhancement for electron beam and laser excitation can be understood as a result of the different selection rules for these complementary experiments. These results provide a fundamentally new understanding of near-field plasmon–exciton interactions in nanopatch antennas, which is essential for myriad emerging quantum photonic devices.

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具有集成半导体量子点的等离子体纳米贴片天线的近场成像

在过去的十年中，包含数百皮米到几纳米厚的介电间隙的等离子体纳米贴片天线引起了越来越多的关注，因为它们将电磁场限制在非常亚衍射限制的体积内。远场光谱学已经证明了对限制在这些等离子体腔内的激子和色心的光学特性的实质性控制，但近场光谱学对于更好地理解纳米级等离子体 - 发射体相互作用至关重要。在这里，我们通过阴极发光显微镜表征孤立纳米贴片天线的强度和相位分辨等离子体响应。此外，我们探索耦合等离子体激子异质结构的光学和电子束光谱之间的区别，以确定未来纳米级表征和混合纳米光子结构控制的限制和机会。虽然我们在时间分辨光致发光光谱中观察到大量的 Purcell 增强，但在混合纳米光子结构的阴极发光光谱中观察到的 Purcell 增强可以忽略不计。电子束和激光激发测量的 Purcell 增强的显着差异可以理解为这些互补实验的不同选择规则的结果。这些结果提供了对纳米贴片天线中近场等离子体激子相互作用的全新理解，这对于无数新兴的量子光子器件至关重要。