1,254,168 research outputs found
Far-field optical microscope with nanometer-scale resolution based on in-plane surface plasmon imaging
A new far-field optical microscopy technique capable of reaching
nanometer-scale resolution has been developed recently using the in-plane image
magnification by surface plasmon polaritons. This microscopy is based on the
optical properties of a metal-dielectric interface that may, in principle,
provide extremely large values of the effective refractive index n up to
100-1000 as seen by the surface plasmons. Thus, the theoretical diffraction
limit on resolution becomes lambda/2n, and falls into the nanometer-scale
range. The experimental realization of the microscope has demonstrated the
optical resolution better than 50 nm for 502 nm illumination wavelength.
However, the theory of such surface plasmon-based far-field microscope
presented so far gives an oversimplified picture of its operation. For example,
the imaginary part of the metal dielectric constant severely limits the
surface-plasmon propagation and the shortest attainable wavelength in most
cases, which in turn limits the microscope magnification. Here I describe how
this limitation has been overcome in the experiment, and analyze the practical
limits on the surface plasmon microscope resolution. In addition, I present
more experimental results, which strongly support the conclusion of extremely
high spatial resolution of the surface plasmon microscope.Comment: 23 pages, 9 figures, will be published in the topical issue on
Nanostructured Optical Metamaterials of the Journal of Optics A: Pure and
Applied Optics, Manuscript revised in response to referees comment
Reduction formalism for Dirac fermions on de Sitter spacetime
The reduction formulas for Dirac fermions are derived, using the exact
solutions of free Dirac equation on de Sitter spacetime. In the framework of
the perturbation theory one studies the Green functions and derive the
scatering amplitude in the first orders of perturbation theory.Comment: 12 pages, no figure
Increasing transmission efficiency with advanced signal processing
Optical CDMA is an advanced and flexible communication technology with a potential to offer very energy efficient and highly scalable networking. In addition it can also deliver increased physical layer privacy and on-demand bandwidth sharing management. We have developed, extensively investigated, and experimentally demonstrated highly scalable approach to incoherent OCDMA which can very efficiently increase the number of simultaneous users. In addition, the introduction of an advanced photonic signal processing results in an overall system power budget improvement by nearly 3dB. Error-free operation with the BER less than 10-12 was achieved. We have also shown that with demonstrated approach we can dramatically improve number of simultaneous network users (up to ten times) while keeping the related hardware count unchanged. By comparing this results to DWDM concept, this substantial increase in number of simultaneous users did not require to add any additional wavelength laser sources and was achieved by employing just three communication wavelengths
D-brane categories
This is an exposition of recent progress in the categorical approach to
D-brane physics. I discuss the physical underpinnings of the appearance of
homotopy categories and triangulated categories of D-branes from a string field
theoretic perspective, and with a focus on applications to homological mirror
symmetry.Comment: 37 pages, IJMPA styl
Solar-Terrestrial Simulations of CMEs with a Realistic Initiation Mechanism: Case Study for Active Region 10069
Most simulations of coronal mass ejections (CMEs) to date either focus on the
interplanetary propagation of a giant plasma "blob" without paying too much
attention to its origin and to the formation process or they focus on the
complex evolution of the coronal magnetic field due to (sub-)photospheric
motions which result in an eruption. Here, we present global simulations of
CMEs where coronal motions are used to produce a realistic evolution of the
coronal magnetic field and cause an eruption. We focus on active region 10069,
which produced a number of eruptions in late August 2002, including the August
24, 2002 CME - a fast (~2000 km/s) eruption originating from W81-, as well as a
slower eruption on August 22, 2002 (originating from W62). Using a
three-dimensional magneto-hydrodynamic (MHD) simulation of these ejections with
the Space Weather Modeling Framework (SWMF), we show how a realistic initiation
mechanism enables us to study the deflection of the CME in the corona and in
the heliosphere. Reconnection of the erupting magnetic field with that of
neighboring streamers and active regions modify the solar connectivity of the
field lines connecting to Earth and change the expected solar energetic
particle fluxes. Comparing the results at 1 AU of our simulations with in situ
observations by the ACE spacecraft, we propose an alternate solar origin for
the shock wave observed at L1 on August 26.Comment: 4 pages, 2 figures, refereed proceedings for Solar Wind 1
Light controlled photon tunneling
Recent measurements of photon tunneling through individual subwavelength
pinholes in a gold film covered with a layer of polydiacetylene (Phys. Rev.
Letters 88, 187402 (2002)) provided strong indication of "photon blockade"
effect similar to Coulomb blockade phenomenon observed in single-electron
tunneling experiments. Here we report first observation of photon tunneling
been blocked (gated) by light at a different wavelength. This observation
suggests possibility of building new class of photon tunneling gating devices
for all-optical signal processing.Comment: 11 pages, 3 figure
Magnifying superlens in the visible frequency range
In this communication we introduce a new design of the magnifying superlens
and demonstrate it in the experiment.Comment: 3pages, 1 figur
- …