Tunable strong exciton-photon coupling in whispering gallery-Fabry Pérot hybrid microcavities

The strong coupling regime lies at the heart of light-matter interactions. It is usually realized by incorporating emitters into an individual optical microcavity. In this work, we report strong exciton-photon coupling in a hybrid whispering gallery-Fabry Pérot double-cavity system. By means of angle-resolved confocal micro-spectroscopy, we observed scale-like emission patterns exhibiting anti-crossing features in the angle-resolved images. Keeping the whispering gallery modes unchanged, we found that the strong coupling regime can be readily controlled by an additionally applied Fabry-Pérot microcavity. The observed patterns are well described by a three-coupled-oscillator model incorporating the strong coupling between excitons and the hybrid photonic modes of the double-cavity system. Our results demonstrate a versatile platform for tunable strong couplings, which could find potential applications in polariton-based optoelectronic devices.