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31.
Previous work have shown that the combined effects of negative third-order dispersion (TOD) and Raman self-scattering (RSS) can significantly enhance soliton compression in dispersion decreasing fibers (DDFs). In this paper, the effects of the negative TOD coefficient and the effective amplification of DDF′s on the performance of soliton compression are investigated. It is shown that for a given initial soliton width and a given effective amplification, there exists an optimum value of the negative TOD coefficient of the DDF at which the enhancement in soliton compression is maximum. It is also shown that the compression enhancement saturates when the effective amplification exceeds a certain value, which has been explained as a compromise between the higher-order effects induced increase of the ratio of input to output group-velocity dispersion coefficients of the DDF and the TOD induced non-adiabatic compression characteristics. The dependence of the compression enhancement on the initial soliton width have also be studied and the scheme is found works well for solitons with initial widths less than 3 ps. 相似文献
32.
33.
It is useful to state propagation laws for a self-focusing laser beam or a soliton in group-theoretical form to be called
Lie-optical form for being able to predict self-focusing dynamics conveniently and amongst other things, the geometrical phase.
It is shown that the propagation of the gaussian laser beam is governed by a rotation group in a non-absorbing medium and
by the Lorentz group in an absorbing medium if the additional symmetry of paraxial propagation is imposed on the laser beam.
This latter symmetry, however, needs care in its implementation because the electromagnetic wave of the laser sees a different
refractive index profile than the laboratory observer in this approximation. It is explained how to estimate this non-Taylor
paraxial power series approximation. The group theoretical laws so-stated are used to predict the geometrical or Berry phase
of the laser beam by a technique developed by one of us elsewhere. The group-theoretical Lie-optic (or ABCD) laws are also
useful in predicting the laser behavior in a more complex optical arrangement like in a laser cavity etc. The nonlinear dynamical
consequences of these laws for long distance (or time) predictions are also dealt with. Ergodic dynamics of an ensemble of
laser beams on the torus during absorptionless self-focusing is discussed in this context. From the point of view of new physics
concepts, we introduce a stroboscopic invariant torus and a stroboscopic generating function in classical mechanics that is
useful for long-distance predictions of absorptionless self-focusing. 相似文献
34.
E. Lundh 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(3):517-520
Two effects are identified that affect the visibility of the
Mott transition in an atomic gas in an optical lattice confined
in a power-law potential. The transition can be made more
pronounced by increasing the power law, but at the same time,
experimental uncertainty in the number of particles will
induce corresponding fluctuations in the measured condensate
fraction. Calculations in two dimensions
indicate that a potential slightly more flat-bottomed than a
quadratic one is to be preferred for a wide range of
particle number fluctuation size. 相似文献
35.
36.
Novel effects resulting from joint action of chirality and non-linearity are discussed using a basic equation describing the
temporal evolution of fields in a chiral medium with Kerr non-linearity. The spatial chirality effect is characterized through
the Born-Fedorov formalism. Our simulations are based on the split-step Fourier method and the solution of the Stokes parameters.
The numerical results show the chiral effect on solitons with circular polarization and mixed polarization spatial solitons. 相似文献
37.
The coupling effect and stability property of symmetric bright holographic soliton pairs have been investigated numerically. Results show that when any one of the two solitary beams from a pair is perturbed in amplitude or width, both beams will be affected by such a perturbation via the coupling effect between the beams, thus resulting in both beams propagating in the medium without a constant shape; however, these two solitary beams are still stable against small perturbations. When both solitary beams from a pair are perturbed simultaneously in amplitude, for some given absolute values of the perturbations, the two beams are stable against these perturbations if both beams are perturbed with the same sign, whereas are unstable with the different signs. When the two beams are simultaneously perturbed in width, both beams exhibit their stability property similar to that when only one beam is perturbed no matter whether both perturbations have the same or different signs. 相似文献
38.
Control of soliton characteristics of the condensate by an arbitrary x-dependent external potential 下载免费PDF全文
This paper presents a family of soliton solutions of the one-dimensional nonlinear Schrdinger equation which describes the dynamics of the dark solitons in Bose-Einstein condensates with an arbitrary x-dependent external potential.The obtained results show that the external potential has an important effect on the dark soliton dynamical characteristics of the condensates.The amplitude,width,and velocity of the output soliton are relative to the source position of the external potential.The smaller the amplitude of the soliton is,the narrower its width is,and the slower the soliton propagates.The collision of two dark solitons is nearly elastic. 相似文献
39.
C. F. Liu Y. Tang 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,70(2):193-199
We provide a mixing model to explore the metastable state
and the macroscopic quantum tunneling (MQT) of binary mixtures. For , we first observe the two condensates form the
symmetry-breaking state (SBS) and then suddenly transfer to the
symmetry-preserving state (SPS) through the MQT. The SBS is shown to be the
metastable state in our system. We find the MQT does not spontaneously
arise. The inducement mechanism is the damping but not the excitations. The
damping mechanism can also control the lifetime and the tunneling decay rate
of the SBS. Finally, we further present the origin of these phenomena by
examining the energy of the system. 相似文献
40.
By developing multiple-scale method combined with
Wentzel--Kramer--Brillouin expansion, this paper analytically
studies the modulating effect of weakly periodic potential on the
dynamical properties of the Bose--Einstein condensates (BEC) trapped
in harmonic magnetic traps. A black--grey soliton transition is
observed in the BEC trapped in harmonic magnetic potential, due to
the weakly periodic potential modulating effect. Meanwhile, it finds
that with the slight increase of the weakly periodic potential
strength, the velocity of the soliton decreases, while its width
firstly decreases then increases, a minimum exists there. These
results show that the amplitude, velocity, and width of matter
solitons can be effectively managed by means of a weakly periodic
potential. 相似文献