17,625 research outputs found
Electrical Control of Plasmon Resonance with Graphene
Surface plasmon, with its unique capability to concentrate light into
sub-wavelength volume, has enabled great advances in photon science, ranging
from nano-antenna and single-molecule Raman scattering to plasmonic waveguide
and metamaterials. In many applications it is desirable to control the surface
plasmon resonance in situ with electric field. Graphene, with its unique
tunable optical properties, provides an ideal material to integrate with
nanometallic structures for realizing such control. Here we demonstrate
effective modulation of the plasmon resonance in a model system composed of
hybrid graphene-gold nanorod structure. Upon electrical gating the strong
optical transitions in graphene can be switched on and off, which leads to
significant modulation of both the resonance frequency and quality factor of
plasmon resonance in gold nanorods. Hybrid graphene-nanometallic structures, as
exemplified by this combination of graphene and gold nanorod, provide a general
and powerful way for electrical control of plasmon resonances. It holds promise
for novel active optical devices and plasmonic circuits at the deep
subwavelength scale
Strong exciton-plasmon coupling in semiconducting carbon nanotubes
We study theoretically the interactions of excitonic states with surface
electromagnetic modes of small-diameter (~1 nm) semiconducting single-walled
carbon nanotubes. We show that these interactions can result in strong
exciton-surface-plasmon coupling. The exciton absorption line shape exhibits
Rabi splitting ~0.1 eV as the exciton energy is tuned to the nearest interband
surface plasmon resonance of the nanotube. We also show that the quantum
confined Stark effect may be used as a tool to control the exciton binding
energy and the nanotube band gap in carbon nanotubes in order, e.g., to bring
the exciton total energy in resonance with the nearest interband plasmon mode.
The exciton-plasmon Rabi splitting we predict here for an individual carbon
nanotube is close in its magnitude to that previously reported for hybrid
plasmonic nanostructures artificially fabricated of organic semiconductors on
metallic films. We expect this effect to open up paths to new tunable
optoelectronic device applications of semiconducting carbon nanotubes.Comment: 22 pages, 8 figures, accepted for PR
A tunable plasmonic refractive index sensor with nanoring-strip graphene arrays
In this paper, a tunable plasmonic refractive index sensor with
nanoring-strip graphene arrays is numerically investigated by the finite
difference time domain (FDTD) method. The simulation results exhibit that by
changing the sensing medium refractive index nmed of the structure, the sensing
range of the system is large. By changing the doping level ng, we noticed that
the transmission characteristics can be adjusted flexibly. The resonance
wavelength remains entirely the same and the transmission dip enhancement over
a big range of incidence angles [0,45] for both TM and TE polarizations, which
indicates that the resonance of the graphene nanoring-strip arrays is
insensitive to angle polarization. The above results are undoubtedly a new way
to realize various tunable plasmon devices, and may have a great application
prospect in biosensing, detection and imaging
Plasmon Resonance in Multilayer Graphene Nanoribbons
Plasmon resonance in nanopatterned single layer graphene nanoribbon (SL-GNR),
double layer graphene nanoribbon (DL-GNR) and triple layer graphene nanoribbon
(TL-GNR) structures is studied both experimentally and by numerical
simulations. We use 'realistic' graphene samples in our experiments to identify
the key bottle necks in both experiments and theoretical models. The existence
of electrical tunable plasmons in such stacked multilayer GNRs was first
experimentally verified by infrared microscopy. We find that the strength of
the plasmonic resonance increases in DL-GNR when compared to SL-GNRs. However,
we do not find a further such increase in TL-GNRs compared to DL-GNRs. We
carried out systematic full wave simulations using finite element technique to
validate and fit experimental results, and extract the carrier scattering rate
as a fitting parameter. The numerical simulations show remarkable agreement
with experiments for unpatterned SLG sheet, and a qualitative agreement for
patterned graphene sheet. We believe that further improvements such as
introducing a bandgap into the numerical model could lead to a better
quantitative agreement of numerical simulations with experiments. We also note
that such advanced modeling would first require better quality graphene samples
and accurate measurements
Tunable grating-assisted surface plasmon resonance by use of nano-polymer dispersed liquid crystal electro-optical material
This paper reports on the experimental observation of the displacement of a surface plasmon resonance (SPR) excited by a metallic diffraction grating. This effect is achieved by the use of an electro-optical material composed of nano-sized droplets of liquid crystals dispersed in a host polymer. The average refractive index of this material in the form of a thin film on the undulated metal surface can be modified with the application of an external electric field and to tune the wavelength at which the SPR excitation leads to a reflection minimum. The theoretical design and experimental demonstration of the principle of this component are described
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