Modulation of spontaneous emission near graphene/hBN multilayers

Abstract

The spontaneous emissions of a quantum emitter near three different samples, namely, graphene-covered hexagonal boron nitride (hBN) bulk (monocell), graphene/hBN/graphene sandwich (sandwich), and graphene/hBN/graphene/hBN (double-cell), are investigated in detail. The spontaneous emission decay rate near the graphene/hBN samples can be increased by several orders of magnitude because of the hyperbolic characteristics of hBN. For the monocell, two sharp peaks appear in the Purcell factor curve, corresponding to the hyperbolic frequency ranges of hBN. The Purcell factor can be actively controlled by the chemical potential of graphene via the coupling of surface plasmons (SPs) supported by graphene and hyperbolic phonon polaritons (HPPs) supported by hBN. As the chemical potential increases, the Purcell factor decreases when the distance between the quantum emitter and the sample is less than 1/1000 transition wavelength. Conversely, the Purcell factor increases when the distance ranges from 1/1000 to 1/100 transition wavelength. The interaction between two quantum emitters in the proximity of different samples in reflective configuration is investigated, and the interaction exhibits an oscillation between superradiant and subradiant states in accordance with the separation between the two emitters. The interaction between quantum emitters can also be controlled freely with the chemical potential of graphene. This work provides a meaningful basis for modulating the spontaneous emission, and could be valuable in expanding the application of new and emerging materials in the field of light–matter interaction.