230 research outputs found
Equilibrium and nonequilibrium solitons in a lossy split-step system with lumped amplification
We propose a more realistic version of the recently introduced split-step
model (SSM), which consists of periodically alternating dispersive and
nonlinear segments, by adding uniformly distributed loss and lumped gain to it.
In the case when the loss is exactly balanced by gain, a family of stable
equilibrium solitons (ESs) is found. Unless the system's period L is very
small, saturation is observed in the dependence of the amplitude of the
established ES vs. that of the initial pulse. Stable nonequilibrium solitons
(NESs) are found in the case when the gain slightly exceeds (by up to 3%) the
value necessary to balance the loss. The existence of NESs is possible as the
excessive energy pump is offset by permanent radiation loss, which is confirmed
by computation of the corresponding Poynting vector. Unlike ESs that form a
continuous family of solutions, NES is an isolated solution, which disappears
in the limit of small L, i.e., it cannot be found in the overpumped nonlinear
Schroedinger equation. Interactions between ESs turn out to be essentially the
same as in SSM without loss and gain, while interactions between NESs are
different: two NESs perturb each other by the radiation jets emanating from
them, even if they are separated by a large distance. Moving NESs survive
collisions, changing their velocities.Comment: a latex text file and seven jpg figure files. Physics Letter A, in
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Criteria for selecting children for speech therapy in the public schools
Thesis (Ed.M.)--Boston Universit
Accelerated rogue waves generated by soliton fusion at the advanced stage of supercontinuum formation in photonic crystal fibers
Soliton fusion is a fascinating and delicate phenomenon that manifests itself
in optical fibers in case of interaction between co-propagating solitons with
small temporal and wavelengths separation. We show that the mechanism of
acceleration of trailing soliton by dispersive waves radiated from the
preceding one provides necessary conditions for soliton fusion at the advanced
stage of supercontinuum generation in photonic crystal fibers. As a result of
fusion large intensity robust light structures arise and propagate over
significant distances. In presence of small random noise the delicate condition
for the effective fusion between solitons can easily be broken, making the
fusion induced giant waves a rare statistical event. Thus oblong-shaped giant
accelerated waves become excellent candidates for optical rogue waves.Comment: Optics Letters Journal. In pres
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