  Strong coupling between light and matter is the foundation of promising
quantum photonic devices such as deterministic single photon sources, single
atom lasers and photonic quantum gates, which consist of an atom and a photonic
cavity. Unlike atom-based systems, a strong coupling unit based on an
emitter-plasmonic nanocavity system has the potential to bring these devices to
the microchip scale at ambient conditions. However, efficiently and precisely
positioning a single or a few emitters into a plasmonic nanocavity is
challenging. In addition, placing a strong coupling unit on a designated
substrate location is a demanding task. Here, fluorophore-modified DNA strands
are utilized to drive the formation of particle-on-film plasmonic nanocavities
and simultaneously integrate the fluorophores into the high field region of the
nanocavities. High cavity yield and fluorophore coupling yield are
demonstrated. This method is then combined with e-beam lithography to position
the strong coupling units on designated locations of a substrate. Furthermore,
the high correlation between electronic transition of the fluorophore and the
cavity resonance is observed, implying more vibrational modes may be involved.
Our system makes strong coupling units more practical on the microchip scale
and at ambient conditions and provides a stable platform for investigating
fluorophore-plasmonic nanocavity interaction.
