Scientific Achievement
First unambiguous demonstration and characterization of a plexciton at ambient conditions at its native length scale. A plexciton is a quasiparticle excitation by strongly coupling plasmon–exciton in 2-D WSe2-covered gold nanotrenches.
Significance and Impact
Plexcitons harbor great potential for applications in nanophotonic devices, optoelectronics, and quantum electrodynamics. This work provides a platform to form and directly access a plexciton at ambient conditions.
Research Details
- We combined state-of-the-art nano fabrication to create this open plexciton platform and perfectly match plasmon and exciton energy.
- State of the art hyperspectral near field imaging developed at TMF allowed the most direct characterization of a plexcitons so far.
- Benchmarking a comprehensive theoretical modeling of a plexciton in this specific structure by comparing it to the direct measurements.
Zhou, J., Gonçalves, P.A.D., Riminucci, F., Dhuey, S., Barnard, E.S., Schwartzberg, A., Garcia de Abajo, F.J., Wber-Bargioni, A. Nat Commun 15, 9583 (2024). https://doi.org/10.1038/s41467-024-53669-5
Research Summary
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, a team of Foundry staff and users investigate the formation and emission characteristics of plexcitons, arising from the interaction between surface plasmons in narrow gold nanotrenches and excitons in monolayer WSe2. They studied this strong plasmon–exciton coupling in both the far-field and the near-field. Specifically, they observed a Rabi splitting in the far-field reflection spectra of about 80 meV under ambient conditions, consistent with their theoretical modeling. Using a custom-designed near-field probe, they found that plexciton emission originates predominantly from the lower-frequency branch, which they directly probed and mapped its local field distribution. They precisely determined the plexcitonʼs spatial extension, similar to the trench width, with nanometric precision by collecting spectra at controlled probe locations. This 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.
