435 research outputs found
Discrete light localization in one dimensional nonlinear lattices with arbitrary non locality
We model discrete spatial solitons in a periodic nonlinear medium
encompassing any degree of transverse non locality. Making a convenient
reference to a widely used material -nematic liquid crystals-, we derive a new
form of the discrete nonlinear Schrodinger equation and find a novel family of
discrete solitons. Such self-localized solutions in optical lattices can exist
with an arbitrary degree of imprinted chirp and a have breathing character. We
verify numerically that both local and non local discrete light propagation and
solitons can be observed in liquid crystalline arrays.Comment: Extended version with 6 pages and 4 Figures, to appear in Phys. Rev.
Nonlinearly-enhanced energy transport in many dimensional quantum chaos
By employing a nonlinear quantum kicked rotor model, we investigate the
transport of energy in multidimensional quantum chaos. Parallel numerical
simulations and analytic theory demonstrate that the interplay between
nonlinearity and Anderson localization establishes a perfectly classical
correspondence in the system, neglecting any quantum time reversal. The
resulting dynamics exhibits a nonlinearly-induced, enhanced transport of energy
through soliton wave particles.Comment: 4 pages, 3 figures, submitte
Time-reversal focusing of an expanding soliton gas in disordered replicas
We investigate the properties of time reversibility of a soliton gas,
originating from a dispersive regularization of a shock wave, as it propagates
in a strongly disordered environment. An original approach combining
information measures and spin glass theory shows that time reversal focusing
occurs for different replicas of the disorder in forward and backward
propagation, provided the disorder varies on a length scale much shorter than
the width of the soliton constituents. The analysis is performed by starting
from a new class of reflectionless potentials, which describe the most general
form of an expanding soliton gas of the defocusing nonlinear Schroedinger
equation.Comment: 7 Pages, 6 Figure
Bistability and instability of dark-antidark solitons in the cubic-quintic nonlinear Schroedinger equation
We characterize the full family of soliton solutions sitting over a
background plane wave and ruled by the cubic-quintic nonlinear Schroedinger
equation in the regime where a quintic focusing term represents a saturation of
the cubic defocusing nonlinearity. We discuss existence and properties of
solitons in terms of catastrophe theory and fully characterize bistability and
instabilities of the dark-antidark pairs, revealing new mechanisms of decay of
antidark solitons.Comment: 8 pages, 10 figures, accepted in PR
Modelling of the dynamic interaction between a reacting spray and an acoustic field in a turbulent combustor
The work presented in this paper is a first attempt at tracing both the vaporization droplet his-tory and the momentum exchange between the liquid and gas phase, in a reacting flow field exposed to acoustic propagation waves. The liquid phase is tracked with a Lagrangian ap-proach, while the carrier gas phase is modelled in an Eulerian framework, based in a two-way coupling interaction, under the main assumptions of dilute regime and infinite thermal con-ductivity. Acoustic propagating waves will eventually affect the combustion dynamic due to oscillating heat released by the flame. Aim of this work is to assess a strategy to estimate the effect of an oscillating gas velocity field on: droplet displacement, redistribution of the char-acteristic droplet diameters, changes in the evaporation rate. Assuming the hypothesis of di-lute regime as valid, the study is carried out by means of a non-dimensional number charac-terization
Nonradiating Photonics with Resonant Dielectric Nanostructures
Nonradiating sources of energy have traditionally been studied in quantum
mechanics and astrophysics, while receiving a very little attention in the
photonics community. This situation has changed recently due to a number of
pioneering theoretical studies and remarkable experimental demonstrations of
the exotic states of light in dielectric resonant photonic structures and
metasurfaces, with the possibility to localize efficiently the electromagnetic
fields of high intensities within small volumes of matter. These recent
advances underpin novel concepts in nanophotonics, and provide a promising
pathway to overcome the problem of losses usually associated with metals and
plasmonic materials for the efficient control of the light-matter interaction
at the nanoscale. This review paper provides the general background and several
snapshots of the recent results in this young yet prominent research field,
focusing on two types of nonradiating states of light that both have been
recently at the center of many studies in all-dielectric resonant meta-optics
and metasurfaces: optical {\em anapoles} and photonic {\em bound states in the
continuum}. We discuss a brief history of these states in optics, their
underlying physics and manifestations, and also emphasize their differences and
similarities. We also review some applications of such novel photonic states in
both linear and nonlinear optics for the nanoscale field enhancement, a design
of novel dielectric structures with high- resonances, nonlinear wave mixing
and enhanced harmonic generation, as well as advanced concepts for lasing and
optical neural networks.Comment: 22 pages, 9 figures, review articl
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