Strongly enhanced light-matter interaction in a hybrid photonic-plasmonic resonator

We propose a hybrid photonic-plasmonic resonant structure which consists of a metal nanoparticle (MNP) and a whispering-gallery-mode (WGM) microcavity. It is found that the hybrid mode enables a strong interaction between the light and matter, and the single-atom cooperativity is enhanced by more than two orders of magnitude compared to that in a bare WGM microcavity. This improvement originates from two aspects: the MNP offers a highly enhanced local field in the vicinity of an emitter, and, interestingly, the high-Q property of WGMs can be maintained in the presence of the MNP. Thus the present system has advantages over a single microcavity or a single MNP, and holds potential in quantum optics, nonlinear optics, and highly sensitive biosensing.