Zhou Junze, Gonçalves P A D, Riminucci Fabrizio, Dhuey Scott, S Barnard Edward, Schwartzberg Adam, García de Abajo F Javier, Weber-Bargioni Alexander
The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, USA.
ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), Spain.
Nat Commun. 2024 Nov 6;15(1):9583. doi: 10.1038/s41467-024-53669-5.
Probing strongly coupled quasiparticle excitations at their intrinsic length scales offers unique insights into their properties and facilitates the design of devices with novel functionalities. In this work, we investigate the formation and emission characteristics of plexcitons, arising from the interaction between surface plasmons in narrow gold nanotrenches and excitons in monolayer WSe. We study this strong plasmon-exciton coupling in both the far-field and the near-field. Specifically, we observe a Rabi splitting in the far-field reflection spectra of about 80 meV under ambient conditions, consistent with our theoretical modeling. Using a custom-designed near-field probe, we find that plexciton emission originates predominantly from the lower-frequency branch, which we can directly probe and map its local field distribution. We precisely determine the plexciton's spatial extension, similar to the trench width, with nanometric precision by collecting spectra at controlled probe locations. Our work opens exciting prospects for nanoscale mapping and engineering of plexcitons in complex nanostructures with potential applications in nanophotonic devices, optoelectronics, and quantum electrodynamics in nanoscale cavities.
在其本征长度尺度上探测强耦合准粒子激发，能为其性质提供独特见解，并有助于设计具有新颖功能的器件。在这项工作中，我们研究了窄金纳米沟槽中的表面等离子体激元与单层WSe₂中的激子相互作用产生的复合激子的形成和发射特性。我们在远场和近场中研究这种强等离子体激元 - 激子耦合。具体而言，我们在环境条件下观察到远场反射光谱中的拉比分裂约为80 meV，这与我们的理论模型一致。使用定制设计的近场探针，我们发现复合激子发射主要源于低频分支，我们可以直接探测并绘制其局部场分布。通过在受控的探针位置收集光谱，我们以纳米精度精确确定了复合激子的空间扩展，其与沟槽宽度相似。我们的工作为复杂纳米结构中复合激子的纳米级映射和工程开辟了令人兴奋的前景，在纳米光子器件、光电子学以及纳米尺度腔中的量子电动力学方面具有潜在应用。
