High Damage Threshold Plasmonic Nanocavity Realized by Single Semiconductor Nanowires for Strong Coupling

Abstract

Strong coupling, as a unique paradigm of cavity quantum electrodynamics, provides an important foundation for exploring novel quantum phenomena. Under ambient conditions, exciton–plasmon strong coupling systems have developed rapidly with various exquisite nanocavity structures proposed and refined. Nanocavities based on metal nanoparticles, such as single-particle and nanoparticle-on-mirror (NPoM), offer excellent compatibility with exciton materials, making them significant platforms for studying plasmon-exciton strong coupling. However, the intrinsic losses of metallic materials severely limit the exploration of novel quantum phenomena such as low-threshold lasing and nonlinear properties. In this work, we propose and realize a plasmonic nanocavity based on high-refractive-index GaAs nanowires positioned on a Au substrate, forming a nanowire-on-mirror (NWoM) architecture. The NWoM nanocavities exhibit strong local field confinement and a significantly enhanced damage threshold, reaching 5.6×10⁶ W/cm². Furthermore, by integrating the nanocavity with monolayer WSe₂, we successfully realized the strong coupling at room temperature. By tuning the diameters of the dielectric nanowires, we observe the characteristic anticrossing behavior and achieve a Rabi splitting of 140 meV. This study lays the foundation for future investigations into more efficient quantum behaviors and provides a new approach to designing low-loss strong coupling systems.