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

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<i>×</i>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.