Strong coupling between plasmonic nanocavity gold nanorods and quantum dots emitter.

The discovery of hybrid states in strong coupling interaction has gained growing attention in cavity-quantum electrodynamics research owing to its fundamental directives and potential in advanced optical applications. The ultra-confined mode volume of plasmonic cavity gold nanorods (AuNRs), particularly at the nanorod tip "hotspot" provides a large coupling strength, a prerequisite for a coherent energy exchange in the strong coupling regime. Here, we reported a remarkable Rabi splitting of ∼231 meV between gold nanorods longitudinal localized surface plasmon resonance (LLSPR) mode and quantum dots (QDs) at ambient conditions, monitored by dielectric medium tuning. Numerical simulations confirmed the result, displaying absorption spectral splitting.