Surface plasmon enhancement of spontaneous emission in graphene waveguides

MAURO CUEVAS

JOURNAL OF OPTICS. A, PURE AND APPLIED OPTICS (PRINT)

IOP PUBLISHING LTD

Lugar: Londres; Año: 2016 vol. 18 p. 105003 - 105016

1464-4258

This work analyzes the spontaneous emission of a single emitter placed near the graphenewaveguide formed by two parallel graphene monolayers, with an insulator spacer layer. In thiscase, the eigenmodes supported by the structure, such as surface plasmon and wave guidedmodes, provide decay channels for the electric dipole placed close to the waveguide. Wecalculated the contribution to the decay rate of symmetric and antisymmetric eigenmodes as afunction of frequency and the orientation of the emitter. Our results show that the modification ofthe spontaneous emission due to excitation of guided modes is much lower than thecorresponding decays through the excitation of symmetric and antisymmetric surface plasmons,for which, the spontaneous emission is dramatically enhanced. As a consequence of the highconfinement of surface plasmons in the graphene waveguide, we found that the decay rate of theemitter with vertical orientation (with respect to graphene sheets) is twice the correspondingdecay of the same emitter with parallel orientation in the whole frequency range where surfaceplasmon modes exist. Differently from metallo-dielectric structures, where structural parametersdetermine the range and magnitude of this emission, our work shows that, by dynamically tuningthe chemical potential of graphene, the spectral region where the decay rate is enhanced can bechosen over a wide range.