56 research outputs found
A Potential of Incoherent Attraction Between Multidimensional Solitons
We obtain analytical expressions for an effective potential of interaction
between two- and three-dimensional (2D and 3D) solitons (including the case of
2D vortex solitons) belonging to two different modes which are incoherently
coupled by cross-phase modulation. The derivation is based on calculation of
the interaction term in the full Hamiltonian of the system. An essential
peculiarity is that, in the 3D case, as well as in the case of 2D solitons with
unequal masses, the main contribution to the interaction potential originates
from a vicinity of one or both solitons, similarly to what was recently found
in the 2D and 3D single-mode systems, while in the case of identical 2D
solitons, the dominating area covers all the space between the solitons. Unlike
the single-mode systems,_stable_ bound states of mutually orbiting solitons are
shown to be possible in the bimodal system.Comment: latex, no figures, submitted to Physics Letters
A fractal-based fibre for ultra-high throughput optical probes
A core component of all scanning near-field optical microscopy
(SNOM) systems is the optical probe, which has evolved greatly but still
represents the limiting component for the system. Here, we introduce a
new type of optical probe, based on a Fractal Fibre which is a special class
of photonic crystal fibre (PCF), to directly address the issue of increasing
the optical throughput in SNOM probes. Optical measurements through
the Fractal Fibre probes have shown superior power levels to that of
conventional SNOM probes. The results presented in this paper suggest
that a novel fibre design is critical in order to maximize the potential of the
SNOM
Rotating optical soliton clusters
We introduce the concept of soliton clusters -- multi-soliton bound states in
a homogeneous bulk optical medium, and reveal a key physical mechanism for
their stabilization associated with a staircase-like phase distribution that
induces a net angular momentum and leads to cluster rotation. The ringlike
soliton clusters provide a nontrivial generalization of the concepts of
two-soliton spiraling, optical vortex solitons, and necklace-type optical
beams.Comment: 4 pages, 5 figure
Induced Coherence and Stable Soliton Spiraling
We develop a theory of soliton spiraling in a bulk nonlinear medium and
reveal a new physical mechanism: periodic power exchange via induced coherence,
which can lead to stable spiraling and the formation of dynamical two-soliton
states. Our theory not only explains earlier observations, but provides a
number of predictions which are also verified experimentally. Finally, we show
theoretically and experimentally that soliton spiraling can be controled by the
degree of mutual initial coherence.Comment: 4 pages, 5 figure
A Potential of Interaction between Two- and Three-Dimensional Solitons
A general method to find an effective potential of interaction between far
separated 2D and 3D solitons is elaborated, including the case of 2D vortex
solitons. The method is based on explicit calculation of the overlapping term
in the full Hamiltonian of the system (_without_ assuming that the ``tail'' of
each soliton is not affected by its interaction with the other soliton, and, in
fact,_without_ knowing the exact form of the solution for an isolated soliton -
the latter problem is circumvented by reducing a bulk integral to a surface
one). The result is obtained in an explicit form that does not contain an
artificially introduced radius of the overlapping region. The potential applies
to spatial and spatiotemporal solitons in nonlinear optics, where it may help
to solve various dynamical problems: collisions, formation of bound states
(BS's), etc. In particular, an orbiting BS of two solitons is always unstable.
In the presence of weak dissipation and gain, the effective potential can also
be derived, giving rise to bound states similar to those recently studied in 1D
models.Comment: 29 double-spaced pages in the latex format and 1 figure in the ps
format. The paper will appear in Phys. Rev.
Instabilities of Higher-Order Parametric Solitons. Filamentation versus Coalescence
We investigate stability and dynamics of higher-order solitary waves in
quadratic media, which have a central peak and one or more surrounding rings.
We show existence of two qualitatively different behaviours. For positive phase
mismatch the rings break up into filaments which move radially to initial ring.
For sufficient negative mismatches rings are found to coalesce with central
peak, forming a single oscillating filament.Comment: 5 pages, 7 figure
Multi-component optical solitary waves
We discuss several novel types of multi-component (temporal and spatial)
envelope solitary waves that appear in fiber and waveguide nonlinear optics. In
particular, we describe multi-channel solitary waves in bit-parallel-wavelength
fiber transmission systems for high performance computer networks, multi-colour
parametric spatial solitary waves due to cascaded nonlinearities of quadratic
materials, and quasiperiodic envelope solitons due to quasi-phase-matching in
Fibonacci optical superlattices.Comment: 12 pages, 11 figures; To be published in: Proceedings of the Dynamics
Days Asia-Pacific: First International Conference on Nonlinear Science
(Hong-Kong, 13-16 July, 1999), Editor: Bambi Hu (Elsevier Publishers, 2000
Polychromatic solitons in a quadratic medium
We introduce the simplest model to describe parametric interactions in a
quadratically nonlinear optical medium with the fundamental harmonic containing
two components with (slightly) different carrier frequencies [which is a direct
analog of wavelength-division multiplexed (WDM) models, well known in media
with cubic nonlinearity]. The model takes a closed form with three different
second-harmonic components, and it is formulated in the spatial domain. We
demonstrate that the model supports both polychromatic solitons (PCSs), with
all the components present in them, and two types of mutually orthogonal simple
solitons, both types being stable in a broad parametric region. An essential
peculiarity of PCS is that its power is much smaller than that of a simple
(usual) soliton (taken at the same values of control parameters), which may be
an advantage for experimental generation of PCSs. Collisions between the
orthogonal simple solitons are simulated in detail, leading to the conclusion
that the collisions are strongly inelastic, converting the simple solitons into
polychromatic ones, and generating one or two additional PCSs. A collision
velocity at which the inelastic effects are strongest is identified, and it is
demonstrated that the collision may be used as a basis to design a simple
all-optical XOR logic gate.Comment: 9 pages, 8 figures, accepted to Phys. Rev.
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