63 research outputs found
Nonlinear optical properties of interconnected gold nanoparticles on silicon
International audienceWe report second harmonic generation (SHG) measurements in reflectivity from chains of gold nanoparticles interconnected with metallic bridges. We measured more than 30 times a SHG enhancement when a surface plasmon resonance was excited in the chains of nanoparticles, which was influenced by coupling due to the electrical connectivity of the bridges. This enhancement was confirmed by rigorous coupled wave method calculations and came from high localization of the electric field at the bridge. The introduction of 10% random defects into the chains of nanoparticles dropped the SHG by a factor of 2 and was shown to be very sensitive to the fundamental wavelengt
Modulation of the extraordinary optical transmission by surface acoustic waves
International audienceThe numerical study of periodically nanostructured metallic films exhibiting extraordinary optical transmission (EOT) deposited onto the top of a piezoelectric material is reported. Surface acoustic waves are generated in the piezoelectric substrate and their influence in the transmission spectrum of the EOT structure is studied. It is shown that low frequency acoustic waves can significantly tune the resonance frequency of the EOT structure
All-Dielectric Rod-Type Metamaterials at Optical Frequencies
Light propagation in all-dielectric rod-type metamaterials is studied
theoretically. The electric and magnetic dipole moments of the rods are derived
analytically in the long-wavelength limit. The effective permittivity and
permeability of a square lattice of rods are calculated by homogenizing the
corresponding array of dipoles. The role of dipole resonances in the optical
properties of the rod array is interpreted. This structure is found to exhibit
a true left-handed behavior, confirming previous experiments [L. Peng
\textit{et al.}, Phys. Rev. Lett. \textbf{98}, 157403 (2007)]. A scaling
analysis shows that this effect holds at optical frequencies and can be
obtained by using rods made, for example, of silicon.Comment: 10 pages, 4 figures. The title has been shortened; Figs. 1, 2 and 3
have been modified; Eq. 4 has been corrected (sign error); A few sentences
have been added/rewritte
Surface Plasmon - Guided Mode strong coupling
It is shown that it is possible to realize strong coupling between a surface plasmon and a guided mode in a layered structure. The dispersion relation of such a structure is obtained through the S-matrix algorithm combined with the Cauchy integral technique that allows for rigorous computations of complex poles. The strong coupling is demonstrated by the presence of an anticrossing in the dispersion diagram and simultaneously by the presence of a crossing in the loss diagram. The temporal characteristics of the different modes and the decay of the losses in the propagation of the hybridized surface plasmons are studied
Casimir-Lifshitz force between graphene-based structures out of thermal equilibrium
We study the non equilibrium Casimir-Lifshitz force between graphene-based
parallel structures held at different temperatures and in presence of an
external thermal bath at a third temperature. The graphene conductivity, which
is itself a function of temperature, as well as of chemical potential, allows
us to tune in situ the Casimir-Lifshitz force. We explore different non
equilibrium configurations while considering different values of the graphene
chemical potential. Particularly interesting cases are investigated, where the
force can change sign going from attractive to repulsive or where the force
becomes non monotonic with respect to chemical potential variations, contrary
to the behaviour under thermal equilibrium.Comment: 10 pages, 18 figure
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