Photoswitchable Rabi Splitting in Hybrid Plasmon-Waveguide Modes

Rabi splitting that arises from strong plasmon-molecule coupling has attracted tremendous interests. However, it has remained elusive to integrate Rabi splitting into the hybrid plasmon-waveguide modes (HPWMs), which have advantages of both subwavelength light confinement of surface plasmons and long-range propagation of guided modes in dielectric waveguides. Herein, we explore a new type of HPWMs based on hybrid systems of Al nanodisk arrays covered by PMMA thin films that are doped with photo chromic molecules and demonstrate the photoswitchable Rabi splitting with a maximum splitting energy of 572 meV in the HPWMs by controlling the photoisomerization of the molecules. Through our experimental measurements combined with finite difference time-domain (FDTD) simulations, we reveal that the photoswitchable Rabi splitting arises from the switchable coupling between the HPWMs and molecular excitons. By harnessing the photoswitchable Rabi splitting, we develop all-optical light modulators and rewritable waveguides. The demonstration of Rabi splitting in the HPWMs will further advance scientific research and device applications of hybrid plasmon-molecule systems.