37 research outputs found
Statistics of soliton-bearing systems with additive noise
We present a consistent method to calculate the probability distribution of
soliton parameters in systems with additive noise. Even though a weak noise is
considered, we are interested in probabilities of large fluctuations (generally
non-Gaussian) which are beyond perturbation theory. Our method is a further
development of the instanton formalism (method of optimal fluctuation) based on
a saddle-point approximation in the path integral. We first solve a fundamental
problem of soliton statistics governing by noisy Nonlinear Schr\"odinger
Equation (NSE). We then apply our method to optical soliton transmission
systems using signal control elements (filters, amplitude and phase
modulators).Comment: 4 pages. Submitted to PR
Trapping polarization of light in nonlinear optical fibers: An ideal Raman polarizer
The main subject of this contribution is the all-optical control over the
state of polarization (SOP) of light, understood as the control over the SOP of
a signal beam by the SOP of a pump beam. We will show how the possibility of
such control arises naturally from a vectorial study of pump-probe Raman
interactions in optical fibers. Most studies on the Raman effect in optical
fibers assume a scalar model, which is only valid for high-PMD fibers (here,
PMD stands for the polarization-mode dispersion). Modern technology enables
manufacturing of low-PMD fibers, the description of which requires a full
vectorial model. Within this model we gain full control over the SOP of the
signal beam. In particular we show how the signal SOP is pulled towards and
trapped by the pump SOP. The isotropic symmetry of the fiber is broken by the
presence of the polarized pump. This trapping effect is used in experiments for
the design of new nonlinear optical devices named Raman polarizers. Along with
the property of improved signal amplification, these devices transform an
arbitrary input SOP of the signal beam into one and the same SOP towards the
output end. This output SOP is fully controlled by the SOP of the pump beam. We
overview the sate-of-the-art of the subject and introduce the notion of an
"ideal Raman polarizer"
Quadratic solitons as nonlocal solitons
We show that quadratic solitons are equivalent to solitons of a nonlocal Kerr
medium. This provides new physical insight into the properties of quadratic
solitons, often believed to be equivalent to solitons of an effective saturable
Kerr medium. The nonlocal analogy also allows for novel analytical solutions
and the prediction of novel bound states of quadratic solitons.Comment: 4 pages, 3 figure