Mauro Cuevas

Tunable plasmonic enhancement of light scattering and absorption in graphene-coated subwavelength wires

The electromagnetic response of subwavelength wires coated with a graphene monolayer illuminated by a linearly polarized plane waves is investigated. The results show that the scattering and extintion cross-sections of the coated wire can be dramatically enhanced when the incident radiation resonantly excites localized surface plasmons. The enhancements occur for p--polarized incident waves and for excitation frequencies that correspond to complex poles in the coefficients of the multipole expansion for the scattered field. By dynamically tuning the chemical potential of graphene, the spectral position of the enhancements can be chosen over a wide range.

Surface plasmon enhancement of spontaneous emission in graphene waveguides

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

Critical coupling layer thickness for positive or negative Goos–Hänchen shifts near the excitation of backward surface polaritons in Otto-ATR systems

Fil: Zeller, Mariana Andrea. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisica. Grupo de Electromagnetismo Aplicado; Argentina

Surface polaritons at a negative index material grating

The differences between the resonant response of metallic and metamaterial gratings, both supporting surface polaritons, evidence the different kind of interference processes occurring between the fields radiated by the surface polariton and the fields reflected by the surface without corrugation. As in any resonance phenomenon, complementary information can be obtained by studying the associated homogeneous problem, i.e., by finding the characteristics of the electromagnetic eigenmodes supported by the corrugated interface. In this paper we solve this associated homogeneous problem, showing how a periodic corrugation affects the characteristics of surface polaritons propagating along the interface between a conventional dielectric medium and a metamaterial medium with a negative index of refraction.

Scattering of light from metamaterial gratings with finite length.

Using an integral equation approach based on the Rayleigh hypothesis, we investigate the scattering of a plane wave at the rough surface of a metamaterial with a finite number of sinusoidal grooves. To show the adequacy of the model, we present results that are in agreement with the predictions of physical optics and that quantitatively reproduce the polarization and angular dependences predicted by the C-formalism for metamaterial gratings with an infinite number of grooves.

The Goos-Hänchen effect at the non periodic surface of a negative index metamaterial

We investigate the lateral displacement (Goos-Hänchen lateral shift) of a linearly polarized Gaussian beam reflected from a corrugated surface between a conventional dielectric and a homogeneous isotropic metamaterial with a negative index of refraction. We pay particular attention to effects associated with the resonant excitation of surface plasmon polaritons. The dependence of the lateral displacement on the incident beam parameters is examined in detail and discussed in different situations among which is the total reflection case. We compare these characteristics with the limiting case of reflection of a beam from a surface with infinitely periodic corrugations.