303 research outputs found
Plasmonic angular momentum on metal-dielectric nano-wedges in a sectorial indefinite metamaterial
We present an analytical study to the structure-modulated plasmonic angular
momentum trapped on periodic metal-dielectric nano-wedges in the core region of
a sectorial indefinite metamaterial. Employing a transfer-matrix calculation
and a conformal-mapping technique, our theory is capable of dealing with
realistic configurations of arbitrary sector numbers and rounded wedge tips. We
demonstrate that in the deep-subwavelength regime strong electric field
carrying high azimuthal variation can exist within only ten-nanometer length
scale close to the structural center, and is naturally bounded by a
characteristic radius of the order of hundred-nanometer away from the center.
These extreme confining properties suggest that the structure under
investigation may be superior to the conventional metal-dielectric waveguides
or cavities in terms of nanoscale photonic manipulation.Comment: 16 pages, 9 figure
Nonlocal description of sound propagation through an array of Helmholtz resonators
A generalized macroscopic nonlocal theory of sound propagation in
rigid-framed porous media saturated with a viscothermal fluid has been recently
proposed, which takes into account both temporal and spatial dispersion. Here,
we consider applying this theory capable to describe resonance effects, to the
case of sound propagation through an array of Helmholtz resonators whose
unusual metamaterial properties such as negative bulk moduli, have been
experimentally demonstrated. Three different calculations are performed,
validating the results of the nonlocal theory, relating to the
frequency-dependent Bloch wavenumber and bulk modulus of the first normal mode,
for 1D propagation in 2D or 3D periodic structures.Comment: 19 page
Electron-photon scattering mediated by localized plasmons: A quantitative analysis by eigen-response theory
We show that the scattering interaction between a high energy electron and a
photon can be strongly enhanced by different types of localized plasmons in a
non-trivial way. The scattering interaction is predicted by an eigen-response
theory, numerically verified by finite-difference-time-domain simulation, and
experimentally verified by cathodoluminescence spectroscopy. We find that the
scattering interaction associated with dark plasmons can be as strong as that
of bright plasmons. Such a strong interaction may offer new opportunities to
improve single-plasmon detection and high-resolution characterization
techniques for high quality plasmonic materials.Comment: 4 pages, 4 figures (excluding Supporting Information
Photon Emission Rate Engineering using Graphene Nanodisc Cavities
In this work, we present a systematic study of the plasmon modes in a system
of vertically stacked pair of graphene discs. Quasistatic approximation is used
to model the eigenmodes of the system. Eigen-response theory is employed to
explain the spatial dependence of the coupling between the plasmon modes and a
quantum emitter. These results show a good match between the semi-analytical
calculation and full-wave simulations. Secondly, we have shown that it is
possible to engineer the decay rates of a quantum emitter placed inside and
near this cavity, using Fermi level tuning, via gate voltages and variation of
emitter location and polarization. We highlighted that by coupling to the
bright plasmon mode, the radiative efficiency of the emitter can be enhanced
compared to the single graphene disc case, whereas the dark plasmon mode
suppresses the radiative efficiency
Tunable light-matter interaction and the role of hyperbolicity in graphene-hBN system
Hexagonal boron nitride (hBN) is a natural hyperbolic material which can also
accommodate highly dispersive surface phonon-polariton modes. In this paper, we
examine theoretically the mid-infrared optical properties of graphene-hBN
heterostructures derived from their coupled plasmon-phonon modes. We found that
the graphene plasmon couples differently with the phonons of the two
Reststrahlen bands, owing to their different hyperbolicity. This also leads to
distinctively different interaction between an external quantum emitter and the
plasmon-phonon modes in the two bands, leading to substantial modification of
its spectrum. The coupling to graphene plasmons allows for additional gate
tunability in the Purcell factor, and narrow dips in its emission spectra
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