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在本文中,我们对二维(2D)复数Swift-Hohenberg方程(CSHE)的耗散孤子进行了研究。 显示二维CSHE的平稳至脉动孤子分叉分析。 该方法基于集合坐标法的半分析方法。 该方法是基于从无穷维动力耗散系统到无维模型的简化而构建的。 简化模型有助于大致获得固定解和脉动解之间的边界。 我们分析了脉冲孤子的动力学和特性。 然后,我们获得了Kerr非线性值的饱和度的确定范围的分叉图。 该图揭示了Kerr非线性的饱和度对周期脉动的影响。 结果表明,当Kerr非线性饱和度参数增大时,一周期脉动孤子解会分叉成双周期脉动。
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Journal of Applied Mathematics and Physics, 2018, 6, 2127-2141
http://www.scirp.org/journal/jamp
ISSN Online: 2327-4379
ISSN Print: 2327-4352
DOI:
10.4236/jamp.2018.610179 Oct. 29, 2018 2127 Journal of Applied Mathematics and Physics
Pulsating Solitons in the Two-Dimensional
Complex Swift-Hohenberg Equation
Aladji Kamagaté
1,2
, Alain-Brice Moubissi
3
1
Ecole Supérieure Africaine des Technologies d’Information et de Communication (ESATIC), Abidjan, Côte d’Ivoire
2
Agence Nationale de la Recherche, Paris, France
3
Université des Sciences et Techniques de Masuku, Franceville, Gabon
Abstract
In this paper,
we performed an investigation of the dissipative solitons of
the two-dimensional (2D) Complex Swift-
Hohenberg equation (CSHE).
Stationary to pulsating soliton bifurcation analysis of the 2D CSHE is dis-
played. The approach is based on the semi-
analytical method of collective
coordinate approach. This method is constructed on a reduction from an infi-
nite-dimensional dynamical dissipative system to a finite-dimensi
onal model.
The reduced model helps to obtain approximately the boundaries between
the stationary and pulsating solutions. We analyzed the dynamics and cha-
racteristics of the pulsating solitons. Then we obtained the bifurcation dia-
gram for a definite range
of the saturation of the Kerr nonlinearity values.
This diagram reveals the effect of the saturation of the Kerr nonlinearity on
the period pulsations. The results show that when the parameter of the satu-
ration of the Kerr nonlinearity increases, one period pulsating soliton solu-
tion bifurcates to double period pulsations.
Keywords
Pulsating Solution, Dissipative Soliton, Spatio-Temporal, Collective Coordinate
Approach, Ginzburg-Landau Equation, Complex Swift-Hohenberg Equation,
Spectral Filtering, Bifurcation
1. Introduction
The complex Swift-Hohenberg equation (CSHE) was first suggested by Swift and
Hohenberg [1] as a simple model for the Rayleigh-Bénard instability of roll
waves. This equation models pattern formation arising from an oscillatory insta-
bility [2] [3] with a finite wave number at onset and, as such, it admits solutions
How to cite this paper:
Kamagaté,
A. and
Moubissi
, A.-B. (2018) Pulsating Solitons
in
the Two
-Dimensional Complex Swift-Ho-
henberg Equation
.
Journal of Applied M
a-
thematics and Physics
,
6
, 2127-2141.
https://doi.org/10.4236/jamp.2018.610179
Received:
September 11, 2018
Accepted:
October 26, 2018
Published:
October 29, 2018
Copyright © 201
8 by authors and
Scientific
Research Publishing Inc.
This work is licensed under the Creative
Commons Attribution International
License (CC BY
4.0).
http://creativecommons.org/licenses/by/4.0/
Open Access
A. Kamagaté, A.-B. Moubissi
DOI:
10.4236/jamp.2018.610179 2128 Journal of Applied Mathematics and Physics
in the form of traveling waves. The CSHE has been widely studied both analyti-
cally and numerically [4] [5]. It describes the dynamics of wide-aperture lasers of
class A and C close to the peak gain [6]. Besides lasers, the CSHE has been used
as a model for other nonlinear optical systems. For instance, photorefractive os-
cillator, Ker medium, semiconductor laser, and passively mode-locked lasers
that allow the generation of self-shaped ultra-short pulses in laser systems [7] are
well described by the Complex Swift-Hohenberg order parameter equation. The
CSHE is useful to describe solitons propagation in optical systems with linear
and nonlinear gain, and spectral filtering such as nonlinear polarization rotation
in fiber lasers or communication links including lumped fast absorbers [5]. It
seems clear that the generation of more complex impulse can be extremely de-
scribed by the higher order of the spectral filter.
Initially, one of the generic equations to analyze the dynamics of the dissipa-
tive soliton formation in laser systems with a fast saturable absorber is the com-
plex Cubic-quintic Ginzburg-Landau equation (CGLE) model [8] [9]. Neverthe-
less, the spectral filter of this model is restricted to the second-order term and
can only describe a spectral response with a single maximum, which is not the
case in many experiments. Indeed, the gain spectrum is usually wide and can
have multiple peaks. Thus, in order to make the model more realistic, we need to
add other terms of higher-order spectral filtering to the CGLE, leading to the
complex Swift-Hohenberg equation [9]. The formation of dissipative soliton in
these models has been widely studied in nonlinear dissipative optics. Their
properties and conditions of existence have been investigated extensively, from
fundamental point of view and due to the clear physical meaning in particular
applications [8] [10] [11].
Nonetheless, these studies use purely numerical approaches. Despite the fact
that some families of exact solution of the CSHE [12] can be obtained analyti-
cally, it is apparent that the CSHE can mainly be analyzed only using computer
simulations. Numerical analysis of the CSHE [6] reveals a great variety of pat-
terns and structures such as traveling waves, spiral waves, segregation and com-
petition between stable solutions. In [13] the authors check numerically the va-
lidity of the complex Swift-Hohenberg equation for the lasers. However, solving
numerically the complex Swift-Hohenberg equation for the two-dimensional so-
litons, for a given set of parameters and a given initial condition, is an extremely
lengthy procedure. To overcome this difficulty, semi-analytical methods based
on various physical backgrounds were developed [14]. For instance, in [15] the
authors applied the semi-analytical method to investigate soliton propagation
and generation of stable moving pulses in one dimension and stable vortex soli-
tons in two dimensions. These alternative theoretical semi-analytical tools can
perceive soliton solutions more efficiently in specific domains of the system pa-
rameters [9] [14] [16] [17].
Using the collective variable approach, we have expanded the regions of coex-
istence of 3D dissipative stationary and pulsating solitons in the complex Ginz-
A. Kamagaté, A.-B. Moubissi
DOI:
10.4236/jamp.2018.610179 2129 Journal of Applied Mathematics and Physics
burg-Landau equation with the cubic-quintic nonlinearity [18]. Recently, with
the same approach, we have demonstrated the stationary dissipative solutions of
the 2D complex Swift-Hohenberg equation. Particularly, we mapped the regions
of existence of stationary dissipative soliton in the
( )
,
νε
and
( )
2
,
βγ
planes
[5].
Here, our main purpose is to investigate the pulsating solution of the 2D
CSHE using a variational formulation. On the fact that the dynamics of the dis-
sipative solutions are much more complex, and the numerical simulations are
extremely tedious tasks, the variational approach is useful to study the ground
state since it depends on a trial function and a good set of parameters.
The rest of the paper is organized as follows. We remind in section 2 the col-
lective variable approach and our procedure of determination of the stability
domains of the pulsating solutions. Section 3 is devoted to the findings of the 2D
pulsating CSHE solutions. We illustrate the bifurcation behavior and show that
they can be stable over a wide range of parameter values. Finally, we summarize
with our conclusions in section 4.
2. Stability Studies by Collective Coordinates Theory
In this study, we address the complex Swift-Hohenberg equation in two dimen-
sions. It is helpful to describe soliton propagation in optical systems with linear
and nonlinear gain and spectral filtering. As well, the CSHE relates quantitative-
ly as qualitatively many nonlinear effects, which occur during the propagation.
This equation is also useful for communication links with lumped fast saturable
absorbers or fiber lasers with additive-pulse mode-locking or nonlinear polariza-
tion rotation. The CSHE higher order of the spectral filter is extremely essential
to analyze the generation of more complex impulse, which makes it preferable in
certain situations to the CGLE. The CSHE can be read in this normalized form
[8] [19]:
24
24
2
22
z tt rr
tt ttt
iD i i i
ψ ψ ψ γψψ νψψ
δψ εψψ βψ µψψ γψ
− −− −
=+ ++ +
(1)
Without the additive term
2 ttt
γψ
this equation is the same as the CGLE one,
and here the coefficients
2
,, , ,,,D
µδ β νγγ
and
ε
are real constants. The
right-hand-side of Equation (1) contains the dissipative terms:
2
γ
represents
the higher-order spectral filter term.
,,
δεβ
and
µ
are the coefficients for
linear loss (if negative), nonlinear gain (if positive), spectral filtering (if positive)
and saturation of the nonlinear gain (if negative), respectively. The left-hand
side holds the conservative terms: namely,
( )
11D =+−
which is for the ano-
malous (normal) dispersion propagation regime and
ν
which represents, if
negative, the saturation coefficient of the Kerr nonlinearity.
γ
stands for Kerr
nonlinearity coefficient. In this present study, the dispersion is anomalous, and
ν
is kept relatively small.
It is clear that the physical meaning of each term of the Equation (1) depends
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