599 research outputs found
Resonant photon tunneling enhancement of the van der Waals friction
We study the van der Waals friction between two flat metal surfaces in
relative motion. For good conductors we find that normal relative motion gives
a much larger friction than for parallel relative motion. The friction may
increase by many order of magnitude when the surfaces are covered by
adsorbates, or can support low-frequency surface plasmons. In this case the
friction is determined by resonant photon tunneling between adsorbate
vibrational modes, or surface plasmon modes.Comment: Published in PR
Field Localization and Enhancement of Phase Locked Second and Third Harmonic Generation in Absorbing Semiconductor Cavities
We predict and experimentally observe the enhancement by three orders of
magnitude of phase mismatched second and third harmonic generation in a GaAs
cavity at 650nm and 433nm, respectively, well above the absorption edge. Phase
locking between the pump and the harmonics changes the effective dispersion of
the medium and inhibits absorption. Despite hostile conditions the harmonics
become localized inside the cavity leading to relatively large conversion
efficiencies. Field localization plays a pivotal role and ushers in a new class
of semiconductor-based devices in the visible and UV ranges
Dependences of the Casimir-Polder interaction between an atom and a cavity wall on atomic and material properties
The Casimir-Polder and van der Waals interactions between an atom and a flat
cavity wall are investigated under the influence of real conditions including
the dynamic polarizability of the atom, actual conductivity of the wall
material and nonzero temperature of the wall. The cases of different atoms near
metal and dielectric walls are considered. It is shown that to obtain accurate
results for the atom-wall interaction at short separations, one should use the
complete tabulated optical data for the complex refractive index of the wall
material and the accurate dynamic polarizability of an atom. At relatively
large separations in the case of a metal wall, one may use the plasma model
dielectric function to describe the dielectric properties of wall material. The
obtained results are important for the theoretical interpretation of
experiments on quantum reflection and Bose-Einstein condensation.Comment: 5 pages, 1 figure, iopart.cls is used, to appear in J. Phys. A
(special issue: Proceedings of QFEXT05, Barcelona, Sept. 5-9, 2005
Comparison between experiment and theory for the thermal Casimir force
We analyze recent experiments on measuring the thermal Casimir force with
account of possible background effects. Special attention is paid to the
validity of the proximity force approximation (PFA) used in the comparison
between the experimental data and computational results in experiments
employing a sphere-plate geometry. The PFA results are compared with the exact
results where they are available. The possibility to use fitting procedures in
theory-experiment comparison is discussed. On this basis we reconsider
experiments exploiting spherical lenses of centimeter-size radii.Comment: Plenary talk at the 10th International Conference "Quantum Field
Theory Under the Influence of External Conditions" (Benasque, Spain, 2011);
16 pages, 5 figure
Extraordinary magnetooptical effects and transmission through the metal-dielectric plasmonic systems
We report on significant enhancement of the magnetooptical effects in
gyrotropic systems of a metallic film perforated by subwavelength hole arrays
and a uniform dielectric film magnetized perpendicular to its plane.
Calculations, based on a rigorous coupled-wave analysis, demonstrate the
Faraday and Kerr effect spectra having several resonance peaks in the near
infrared range, some of them coinciding with transmittance peaks. Qualitative
analysis revealed that magnetic polaritons being coupled magnetic-film
waveguiding modes with surface plasmons play a crucial role in the observed
effect.Comment: 10 pages, 3 figure
Phase-change chalcogenide glass metamaterial
Combining metamaterials with functional media brings a new dimension to their
performance. Here we demonstrate substantial resonance frequency tuning in a
photonic metamaterial hybridized with an electrically/optically switchable
chalcogenide glass. The transition between amorphous and crystalline forms
brings about a 10% shift in the near-infrared resonance wavelength of an
asymmetric split-ring array, providing transmission modulation functionality
with a contrast ratio of 4:1 in a device of sub-wavelength thickness.Comment: 3 pages, 3 figure
Experimental observation of the spin Hall effect of light on a nano-metal film via weak measurements
We theorize the spin Hall effect of light (SHEL) on a nano-metal film and
demonstrate it experimentally via weak measurements. A general propagation
model to describe the relationship between the spin-orbit coupling and the
thickness of the metal film is established. It is revealed that the spin-orbit
coupling in the SHEL can be effectively modulated by adjusting the thickness of
the metal film, and the transverse displacement is sensitive to the thickness
of metal film in certain range for horizontal polarization light. Importantly,
a large negative transverse shift can be observed as a consequence of the
combined contribution of the ratio and the phase difference of Fresnel
coefficients.Comment: 5 pages, 4 figure
Surface plasmon resonance under conditions of electromagnetically induced transparency
A scheme for a surface plasmon resonance system under conditions of
electromagnetically induced transparency (EIT) is proposed. The system is
composed of three layers: a prism, a thin metal film, and a hybrid dielectric
consisting of EIT atoms and a background substance. A probe and a coupling
laser beam are input. Corresponding analytical formulas are derived for the
cases when one or both of the laser beams excite surface plasmon polaritons at
the metal/dielectric interface. Under resonance conditions, an extremely sharp
dip appears in the reflectivity-frequency spectrum of the probe field,
revealing new properties of two-dimensional EIT. The reflectivity is extremely
sensitive to shifts in the laser frequencies and atomic levels, and to
variations of permittivity of the substrate. This EIT-SPR system may to be used
for novel magnetometers and biosensors
New approach to the thermal Casimir force between real metals
The new approach to the theoretical description of the thermal Casimir force
between real metals is presented. It uses the plasma-like dielectric
permittivity that takes into account the interband transitions of core
electrons. This permittivity precisely satisfies the Kramers-Kronig relations.
The respective Casimir entropy is positive and vanishes at zero temperature in
accordance with the Nernst heat theorem. The physical reasons why the Drude
dielectric function, when substituted in the Lifshitz formula, is inconsistent
with electrodynamics are elucidated. The proposed approach is the single one
consistent with all measurements of the Casimir force performed up to date. The
application of this approach to metal-type semiconductors is considered.Comment: 14 pages, 6 figures. Proceedings of QFEXT07, to appear in J. Phys.
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