1,241 research outputs found
Quantum gravity simulation by non-paraxial nonlinear optics
We show that an analog of the physics at the Planck scale can be found in the
propagation of tightly focused laser beams. Various equations that occur in
generalized quantum mechanics are formally identical to those describing the
nonlinear nonlocal propagation of nonparaxial laser beams. The analysis
includes a generalized uncertainty principle and shows that the nonlinear
focusing of a light beam with dimensions comparable to the wavelength
corresponds to the spontaneous excitation of the so-called maximally localized
states. The approach, driven by the ideas of the quantum gravity physics,
allows one to predict the existence of self-trapped subwavelength solitary
waves for both focusing and defocusing nonlinearities, and opens the way to
laboratory simulations of phenomena that have been considered to be
inaccessible
Solitonization of the Anderson Localization
We study the affinities between the shape of the bright soliton of the
one-dimensional nonlinear Schroedinger equation and that of the disorder
induced localization in the presence of a Gaussian random potential. With
emphasis on the focusing nonlinearity, we consider the bound states of the
nonlinear Schroedinger equation with a random potential; for the state
exhibiting the highest degree of localization, we derive explicit expressions
for the nonlinear eigenvalue and for the localization length by using
perturbation theory and a variational approach following the methods of
statistical mechanics of disordered systems. We numerically investigate the
linear stability and "superlocalizations". The profile of the disorder averaged
Anderson localization is found to obey a nonlocal nonlinear Schroedinger
equationComment: 5 pages, 3 figure
The Enlightened Game of Life
We investigate a special class of cellular automata (CA) evolving in a
environment filled by an electromagnetic wave. The rules of the Conway's Game
of Life are modified to account for the ability to retrieve life-sustenance
from the field energy. Light-induced self-structuring and self-healing
abilities and various dynamic phases are displayed by the CA. Photo-driven
genetic selection and the nonlinear feedback of the CA on the electromagnetic
field are included in the model, and there are evidences of self-organized
light-localization processes. The evolution of the electromagnetic field is
based on the Finite Difference Time Domain (FDTD) approach. Applications are
envisaged in evolutionary biology, artificial life, DNA replication, swarming,
optical tweezing and field-driven soft-matter.Comment: Revised and enlarged version. Added genetic selection and nonlinear
feedback of the CA on the electromagnetic field. 12 pages, 13 figures. To
appear in the book Game of Life Cellular Automata (Springer 2010, Andy
Adamtzky ed.)
Topological lasing and self-induced transparency in two level systems
The use of virtually lossless topologically isolated edge states may lead to
a novel class of thresholdless lasers operating without inversion. One needs
however to understand if topological states may be coupled to external
radiation and act as active cavities. We study a two-level topological
insulator and show that self-induced transparency pulses can directly excite
edge states. We simulate laser emission by a suitable designed topological
cavity, and show that it can emit tunable radiation. For a configuration of
sites following the off-diagonal Aubry-Andre-Harper model we solve the
Maxwell-Bloch equations in the time domain and provide a first principle
confirmation of topological lasers. Our results open the road to a new class of
light emitters with topological protection for applications ranging from
low-cost energetically-effective integrated lasers sources, also including
silicon photonics, to strong coupling devices for studying ultrafast quantum
processes with engineered vacuum
Complexity of waves in nonlinear disordered media
The statistical properties of the phases of several modes nonlinearly coupled
in a random system are investigated by means of a Hamiltonian model with
disordered couplings. The regime in which the modes have a stationary
distribution of their energies and the phases are coupled is studied for
arbitrary degrees of randomness and energy. The complexity versus temperature
and strength of nonlinearity is calculated. A phase diagram is derived in terms
of the stored energy and amount of disorder. Implications in random lasing,
nonlinear wave propagation and finite temperature Bose-Einstein condensation
are discussed.Comment: 20 pages, 11 Figure
Nonlinear optomechanical pressure
A transparent material exhibits ultra-fast optical nonlinearity and is
subject to optical pressure if irradiated by a laser beam. However, the effect
of nonlinearity on optical pressure is often overlooked, even if a nonlinear
optical pressure may be potentially employed in many applications, as optical
manipulation, biophysics, cavity optomechanics, quantum optics, optical
tractors, and is relevant in fundamental problems as the Abraham-Minkoswky
dilemma, or the Casimir effect. Here we show that an ultra-fast nonlinear
polarization gives indeed a contribution to the optical pressure that also is
negative in certain spectral ranges; the theoretical analysis is confirmed by
first-principles simulations. An order of magnitude estimate shows that the
effect can be observable by measuring the deflection of a membrane made by
graphene.Comment: 10 pages, 6 figures, minor corrections to text and references,
Physical Review A, to be publishe
Bifurcation of gap solitons through catastrophe theory
In the theory of optical gap solitons, slowly-moving finite-amplitude
Lorentzian solutions are found to mediate the transition from bright to
coexistent dark-antidark solitary wave pairs when the laser frequency is
detuned out of the proper edge of a dynamical photonic bandgap. Catastrophe
theory is applied to give a geometrical description of this strongly
asymmetrical 'morphing' process.Comment: 6 pages, 3 figures, submitted to Phys. Rev.
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