Reaching strong light-matter coupling regime with plasmonic nano-cube over mirror array and TMD monolayer

In the strong light-matter interaction regime, quantum vacuum field effects on coupled hybrid states are highly enhanced. One building block of such hybrid quantum system is a plasmonic nanocavity coupled with quantum emitters in the strong coupling (SC) limit and further. Here, we design and fabricate a low-mode volume plasmonic cavity and observe plasmon resonances in the visible range, based on the nanoparticle over mirror (NPoM) array structure. We show spectral tunability of this resonance with the nanostructure dimensions, and good agreement between optical characterization and numerical simulations by FDTD.