Tunable omnidirectional strong light-matter interactions mediated by graphene surface plasmons

In this theoretical work, we report on voltage-controllable hybridization of electromagnetic modes arising from strong interaction between graphene surface plasmons and molecular vibrations. The interaction strength depends strongly on the volume density of molecular dipoles, the molecular relaxation time, and the molecular layer thickness. Graphene offers much tighter plasmonic field confinement and longer carrier relaxation time compared to noble metals, leading to Rabi splitting and hybridized polaritonic modes at three-orders-of-magnitude lower molecular densities. Electrostatically tunable carrier density in graphene allows for dynamic control over the interaction strength. In addition, the flat dispersion band above the light line arising from the deep confinement of the polaritonic modes gives rise to the omnidirectional excitation. Our approach is promising for practical implementations in infrared sensing and detection.