31,384 research outputs found
Wave Energy Amplification in a Metamaterial based Traveling Wave Structure
We consider the interaction between a particle beam and a propagating
electromagnetic wave in the presence of a metamaterial. We show that the
introduction of a metamaterial gives rise to a novel dispersion curve which
determines a unique wave particle relationship, via the frequency dependence of
the metamaterial and the novel ability of metamaterials to exhibit simultaneous
negative permittivity and permeability. Using a modified form of Madey's
theorem we find that the novel dispersion of the metamaterial leads to a
amplification of the EM wave power
Plasmon induced transparency in graphene based terahertz metamaterials
Plasmon induced transparency (PIT) effect in a terahertz graphene
metamaterial is numerically and theoretically analyzed. The proposed
metamaterial comprises of a pair of graphene split ring resonators placed
alternately on both sides of a graphene strip of nanometer scale. The PIT
effect in the graphene metamaterial is studied for different vertical and
horizontal configurations. Our results reveal that there is no PIT effect in
the graphene metamaterial when the centers of both the split ring resonators
and the graphene strip are collinear to each other. This is a noteworthy
feature, as the PIT effect does not vanish for similar configuration in a
metal-based metamaterial structure. We have further shown that the PIT effect
can be tuned by varying the Fermi energy of graphene layer. A theoretical model
using the three level plasmonic system is established in order to validate the
numerical results. Our studies could be significant in designing graphene based
frequency agile ultra-thin devices for terahertz applications
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