Strong Enhancement of Light-Matter Interaction in Graphene Coupled to a Photonic Crystal Nanocavity

We demonstrate a large enhancement in the interaction of light with graphene through coupling with localized modes in a photonic crystal nanocavity. Spectroscopic studies show that a single atomic layer of graphene reduces the cavity reflection by more than a factor of one hundred, while also sharply reducing the cavity quality factor. The strong interaction allows for cavity-enhanced Raman spectroscopy on subwavelength regions of a graphene sample. A coupled mode theory model matches experimental observations and indicates significantly increased light absorption in the graphene layer. The coupled graphene cavity system also enables precise measurements of graphene's complex refractive index.