257 research outputs found
Vector mixed-gap surface solitons
We elucidate the properties of mixed-gap vector surface solitons supported by
the interface between a uniform medium and an optical lattice imprinted in a
Kerr-type nonlinear media. The components of such mixed-gap solitons emerge
from different gaps of lattice spectrum and their mutual trapping results in
the formation of stable vector states. The unstable soliton component is
stabilized by the cross-coupling with the stable component. We show that vector
mixed-gap surface solitons exhibit a new combination of properties of vectorial
surface waves and gap solitons.Comment: 7 pages, 4 figures, to appear in Optics Expres
Highly-asymmetric soliton complexes in parabolic optical lattices
We introduce multipole soliton complexes in optical lattices induced by
nondiffracting parabolic beams. Despite the symmetry-breaking dictated by the
curvature of the lattice channels, we find that complex, asymmetric
higher-order states can be stable. The unique topology of parabolic lattices
affords new types of soliton motion: single solitons launched into the lattice
with nonzero transverse momentum perform periodic oscillations along parabolic
paths.Comment: 12 pages, 4 figures, to appear in Optics Letter
Quasi-compactons and bistability in exciton-polariton condensates
We address stationary patterns in exciton-polariton condensates supported by
a narrow external pump beam, and we discover that even in the absence of
trapping potentials, such condensates may support stable localized stationary
dissipative solutions (quasi-compactons), whose field decays faster than
exponentially or even vanishes everywhere outside the pump spot. More general
conditions lead to dissipative solitons which may display bistability. The
bistability in exciton-polariton condensates, which manifests itself in
simultaneous existence of two stable and one unstable localized solitons with
different amplitudes, widths, and exciton-photon fractions under the same
physical conditions, strongly depends on the width of pump beam and is found to
disappear for sufficiently narrow pump beams
Light beam dynamics in materials with radially-inhomogeneous thermal conductivity
We study the properties of bright and vortex solitons in thermal media with
nonuniform thermal conductivity and homogeneous refractive index, whereby the
local modulation of the thermal conductivity strongly affects the entire
refractive index distribution. While regions where the thermal conductivity is
increased effectively expel light, self-trapping may occur in the regions with
reduced thermal conductivity, even if such regions are located close to the
material boundary. As a result, strongly asymmetric self-trapped beams may form
inside a ring with reduced thermal conductivity and perform persistent rotary
motion. Also, such rings are shown to support stable vortex solitons, which may
feature strongly non-canonical shapes.Comment: 4 pages, 5 figures, to appear in Optics Letter
Soliton percolation in random optical lattices
We introduce soliton percolation phenomena in the nonlinear transport of
light packets in suitable optical lattices with random properties.
Specifically, we address lattices with a gradient of the refractive index in
the transverse plane, featuring stochastic phase or amplitude fluctuations, and
we discover the existence of a disorder-induced transition between
soliton-insu-lator and soliton-conductor regimes. The soliton current is found
to reach its maximal value at intermediate disorder levels and to drastically
decrease in both, almost regular and strongly disordered lattices.Comment: 9 pages, 4 figures, to appear in Optics Expres
Solitons in spiraling Vogel lattices
We address light propagation in Vogel optical lattices and show that such
lattices support a variety of stable soliton solutions in both self-focusing
and self-defocusing media, whose propagation constants belong to domains
resembling gaps in the spectrum of a truly periodic lattice. The
azimuthally-rich structure of Vogel lattices allows generation of spiraling
soliton motion.Comment: 3 pages, 4 figures, to appear in Optics Letter
Bragg-type soliton mirror
We study soliton reflection/transmission at the interface between uniform
medium and the optical lattice with focusing Kerr nonlinearity. We reveal that
such interfaces afford rich new opportunities for controlling the reflection
and transmission coefficients and nonlinear Snell law, the key control
parameters being the spatial frequency and depth of the lattice.Comment: 6 pages, 2 figures, to appear in Optics Expres
Unbreakable PT-symmetry of solitons supported by inhomogeneous defocusing nonlinearity
We consider bright solitons supported by a symmetric inhomogeneous defocusing
nonlinearity growing rapidly enough toward the periphery of the medium,
combined with an antisymmetric gain-loss profile. Despite the absence of any
symmetric modulation of the linear refractive index, which is usually required
to establish a PT-symmetry in the form of a purely real spectrum of modes, we
show that the PT-symmetry is never broken in the present system, and that the
system always supports stable bright solitons, fundamental and multi-pole ones.
Such phenomenon is connected to non-linearizability of the underlying evolution
equation. The increase of the gain-losses strength results, in lieu of the
PT-symmetry breaking, in merger of pairs of different soliton branches, such as
fundamental and dipole, or tripole and quadrupole ones. The fundamental and
dipole solitons remain stable for all values of the gain-loss coefficient.Comment: 4 pages, 4 figures, to appear in Optics Letter
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