137 research outputs found
Broadband diffraction management and self-collimation of white light in photonic lattices
We suggest a novel type of photonic structures where the strength of
diffraction can be managed in a very broad frequency range. We introduce
optimized arrays of curved waveguides where light beams experience
wavelength-independent normal, anomalous, or zero diffraction. Our results
suggest novel opportunities for efficient self-collimation, focusing, and
reshaping of beams produced by white-light and super-continuum sources. We also
show how to manipulate light patterns through multicolor Talbot effect, which
is possible neither in free space nor in conventional photonic lattices.Comment: 5 pages, 4 figures; available at
http://link.aps.org/abstract/PRE/v74/e06660
Discrete surface solitons in semi-infinite binary waveguide arrays
We analyze discrete surface modes in semi-infinite binary waveguide arrays,
which can support simultaneously two types of discrete solitons. We demonstrate
that the analysis of linear surface states in such arrays provides important
information about the existence of nonlinear surface modes and their
properties. We find numerically the families of both discrete surface solitons
and nonlinear Tamm (gap) states and study their stability properties.Comment: 3 pages, 4 figures, submitted to Opt. Let
Soliton control in modulated optically-induced photonic lattices
We discuss soliton control in reconfigurable optically-induced photonic
lattices created by three interfering beams. We reveal novel dynamical regimes
for strongly localized solitons, including binary switching and soliton
revivals through resonant wave mixing.Comment: 7 pages, 5 figures. Content modifie
Surface multi-gap vector solitons
We analyze nonlinear collective effects near surfaces of semi-infinite
periodic systems with multi-gap transmission spectra and introduce a novel
concept of multi-gap surface solitons as mutually trapped surface states with
the components associated with different spectral gaps. We find numerically
discrete surface modes in semi-infinite binary waveguide arrays which can
support simultaneously two types of discrete solitons, and analyze different
multi-gap states including the soliton-induced waveguides with the guided modes
from different gaps and composite vector solitons.Comment: 6 pages, 5 figure
Light Bullets in Nonlinear Periodically Curved Waveguide Arrays
We predict that stable mobile spatio-temporal solitons can exist in arrays of
periodically curved optical waveguides. We find two-dimensional light bullets
in one-dimensional arrays with harmonic waveguide bending and three-dimensional
bullets in square lattices with helical waveguide bending using variational
formalism. Stability of the light bullet solutions is confirmed by the direct
numerical simulations which show that the light bullets can freely move across
the curved arrays. This mobility property is a distinguishing characteristic
compared to previously considered discrete light bullets which were trapped to
a specific lattice site. These results suggest new possibilities for flexible
spatio-temporal manipulation of optical pulses in photonic lattices.Comment: 7 pages, 4 figure
Light propagation and localization in modulated photonic lattices and waveguides
We review both theoretical and experimental advances in the recently emerged
physics of modulated photonic lattices. Artificial periodic dielectric media,
such as photonic crystals and photonic lattices, provide a powerful tool for
the control of the fundamental properties of light propagation in photonic
structures. Photonic lattices are arrays of coupled optical waveguides, where
the light propagation becomes effectively discretized. Such photonic structures
allow one to study many useful optical analogies with other fields, such as the
physics of solid state and electron theory. In particular, the light
propagation in periodic photonic structures resembles the motion of electrons
in a crystalline lattice of semiconductor materials. The discretized nature of
light propagation gives rise to many new phenomena which are not possible in
homogeneous bulk media, such as discrete diffraction and diffraction
management, discrete and gap solitons, and discrete surface waves. Recently, it
was discovered that applying periodic modulation to a photonic lattice by
varying its geometry or refractive index is very much similar to applying a
bias to control the motion of electrons in a crystalline lattice. An interplay
between periodicity and modulation in photonic lattices opens up unique
opportunities for tailoring diffraction and dispersion properties of light as
well as controlling nonlinear interactions.Comment: 98 pages, 55 figures, preprint submitted to Physics Report
Shot noise thermometry of the quantum Hall edge states
We use the non-equilibrium bosonization technique to investigate effects of
the Coulomb interaction on quantum Hall edge states at filing factor nu=2,
partitioned by a quantum point contact (QPC). We find, that due to the
integrability of charge dynamics, edge states evolve to a non-equilibrium
stationary state with a number of specific features. In particular, the noise
temperature of a weak backscattering current between edge channels is linear in
voltage bias applied at the QPC, independently of the interaction strength. In
addition, it is a non-analytical function of the QPC transparency T and scales
as Tln(1/T) at T<< 1. Our predictions are confirmed by exact numerical
calculations.Comment: 5 pages, 3 figure
Energy relaxation at quantum Hall edge
In this work we address the recent experiment of Altimiras and collaborators,
where an electron distribution function at the quantum Hall (QH) edge at
filling factor 2 has been measured with high precision. It has been reported
that the energy of electrons injected into one of the two chiral edge channels
with the help of a quantum point contact (QPC) is equally distributed between
them, in agreement with earlier predictions, one being based on the Fermi gas
approach, and the other utilizing the Luttinger liquid theory. We argue that
the physics of the energy relaxation process at the QH edge may in fact be more
rich, providing the possibility for discriminating between two physical
pictures in experiment. Namely, using the recently proposed non-equilibrium
bosonization technique we evaluate the electron distribution function and find
that the initial "double-step" distribution created at a QPC evolves through
several intermediate asymptotics, before reaching eventual equilibrium state.
At short distances the distribution function is found to be asymmetric due to
non-Gaussian current noise effects. At larger distances, where noise becomes
Gaussian, the distribution function acquires symmetric Lorentzian shape.
Importantly, in the regime of low QPC transparencies T the width of the
Lorentzian scales linearly with T, in contrast to the case of equilibrium Fermi
distribution, whose width scales as square root of T. Therefore, we propose to
do measurements at low QPC transparencies. We suggest that the missing energy
paradox may be explained by the nonlinear dispersion of the spectrum of edge
states.Comment: 14 pages, 6 figure
Nonlinear directional coupler for polychromatic light
We demonstrate that nonlinear directional coupler with special bending of
waveguide axes can be used for all-optical switching of polychromatic light
with very broad spectrum covering all visible region. The bandwidth of
suggested device is enhanced five times compared to conventional couplers. Our
results suggest novel opportunities for creation of all-optical logical gates
and switches for polychromatic light with white-light and super-continuum
spectrum.Comment: 3 pages, 3 figure
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