共查询到20条相似文献,搜索用时 31 毫秒
1.
Bingzhi Zhang 《Physics letters. A》2011,375(7):1110-1115
We investigate the formation of polarization vortex spatial optical solitons in optical lattice induced by a non-diffracting Bessel beam. The properties of these solitons in zeroth-order and first-order Bessel lattices with focusing and defocusing Kerr nonlinearity are discussed. It is found that these solitons have some analogies with phase vortex solitons carrying single positive or negative topological charge in these lattices. Besides, these polarization vortex solitons have complicated dynamical characteristic and can be stabilized in some parameter region. 相似文献
2.
Feshbach resonance management of vector solitons in two-component Bose—Einstein condensates 下载免费PDF全文
We consider two coupled Gross-Pitaevskii equations describing a two-component Bose-Einstein condensate with time-dependent atomic interactions loaded in an external harmonic potential,and investigate the dynamics of vector solitons.By using a direct method,we construct a novel family of vector soliton solutions,which are the linear combination between dark and bright solitons in each component.Our results show that due to the superposition between dark and bright solitons,such vector solitons possess many novel and interesting properties.The dynamics of vector solitons can be controlled by the Feshbach resonance technique,and the vector solitons can keep the dynamic stability against the variation of the scattering length. 相似文献
3.
We review recent theoretical results concerning the existence, stability and unique features of families of bright vortex
solitons (doughnuts, or ‘spinning’ solitons) in both conservative and dissipative cubic-quintic nonlinear media. 相似文献
4.
The fractional quadric-cubic coupled nonlinear Schrödinger equation is concerned, and vector symmetric and antisymmetric soliton solutions are obtained by the square operator method. The relationship between the Lévy index and the amplitudes of vector symmetric and antisymmetric solitons is investigated. Two components of vector symmetric and antisymmetric solitons show a positive and negative trend with the Lévy index, respectively. The stability intervals of these solitons and the propagation constants corresponding to the maximum and minimum instability growth rates are studied. Results indicate that vector symmetric solitons are more stable and have better interference resistance than vector antisymmetric solitons. 相似文献
5.
利用强非局域非线性介质中傍轴光束传输的修正Snyder-Mitchell模型讨论了两束共线(即光束中心和传输方向都相同)拉盖尔-高斯型光孤子(CLGS)构成的涡旋光孤子传输过程。在一定条件下,涡旋光束在传输过程中,光束截面光斑发生旋转现象,但光束的束宽保持不变,称之为旋转涡旋光孤子。涡旋光孤子旋转的现象可以通过叠加光场中的古依相位来解释。结果展现了几个旋转涡旋光孤子在传输过程中的旋转现象和强非局域介质中多环形旋转涡旋光孤子的传输。 相似文献
6.
7.
The Hirota equation can be used to describe the wave propagation of an ultrashort optical field. In this paper, the multi-component Hirota (alias n-Hirota, i.e. n-component third-order nonlinear Schrödinger) equations with mixed non-zero and zero boundary conditions are explored. We employ the multiple roots of the characteristic polynomial related to the Lax pair and modified Darboux transform to find vector semi-rational rogon-soliton solutions (i.e. nonlinear combinations of rogon and soliton solutions). The semi-rational rogon-soliton features can be modulated by the polynomial degree. For the larger solution parameters, the first m (m < n) components with non-zero backgrounds can be decomposed into rational rogons and grey-like solitons, and the last n − m components with zero backgrounds can approach bright-like solitons. Moreover, we analyze the accelerations and curvatures of the quasi-characteristic curves, as well as the variations of accelerations with the distances to judge the interaction intensities between rogons and grey-like solitons. We also find the semi-rational rogon-soliton solutions with ultra-high amplitudes. In particular, we can also deduce vector semi-rational solitons of the n-component complex mKdV equation. These results will be useful to further study the related nonlinear wave phenomena of multi-component physical models with mixed background, and even design the related physical experiments. 相似文献
8.
We address the existence,stability and propagation dynamics of solitons supported by large-scale defects surrounded by the harmonic photonic lattices imprinted in the defocusing saturable nonlinear medium.Several families of soliton solutions,including flat-topped,dipole-like,and multipole-like solitons,can be supported by the defected lattices with different heights of defects.The width of existence domain of solitons is determined solely by the saturable parameter.The existence domains of various types of solitons can be shifted by the variations of defect size,lattice depth and soliton order.Solitons in the model are stable in a wide parameter window,provided that the propagation constant exceeds a critical value,which is in sharp contrast to the case where the soliton trains is supported by periodic lattices imprinted in defocusing saturable nonlinear medium.We also find stable solitons in the semi-infinite gap which rarely occur in the defocusing media. 相似文献
9.
In this paper we have presented a theoretical investigation on the propagation properties of incoherent solitons in photorefractive media which is characterized by noninstantaneous saturating nonlinearity. Using mutual coherence function approach, we have obtained the equation of existence curve for such solitons. We have discussed the coherence characteristics of these solitons. We have found that solitons with a particular radius can possess two different critical powers. The dynamical evolution of these solitons has been discussed in detail by both analytical and numerical simulation. 相似文献
10.
We show that bright-dark vector solitons are possible in biased two-photon photorefractive crystals under steady-state conditions. The analytical solutions of these vector solitons can be obtained if the intensities of the two vector components are approximately equal. When the intensities of the two vector components differ, the vector soliton pair solutions can be determined using simple numerical integration procedures. The stability of the bright-dark vector solitons has been investigated numerically. 相似文献
11.
We elucidate the existence, stability and propagation
dynamics of multi-spot soliton packets in focusing saturable media.
Such solitons are supported by an interface beside which two
harmonically photonic lattices with different modulation depths are
imprinted. We show that the surface model can support stable
higher-order structures in the form of asymmetrical surface soliton
trains, which is in sharp contrast to homogeneous media or uniform
harmonic lattice modulations where stable asymmetrical multi-peaked
solitons do not exist. Surface trains can be viewed as higher-order
soliton states bound together by several different lowest order
solitons with appropriate relative phases. Their existence as stable
objects enriches the concept of compact manipulation of several
different solitons as a single entity and offers additional
freedom to control the shape of solitons by adjusting the modulation
depths beside the interface. 相似文献
12.
一维光伏空间灰孤子及其稳定性研究 总被引:4,自引:2,他引:2
从考虑背景光的光伏作用后的光束在光伏媒质中传播的方程出发,证明了在折射率改变为正的光伏媒质中也可以形成灰孤子。光束以灰孤子状态在光伏晶体中传播时,其横向相位必须具有一个与光强分布有关的形式分布,表达式为φ(s)=v[η-∫y^-2(η)dη],其中v是灰孤子的横向运动速度,η是无量纲化坐标,y(η)是归一化的光场振幅。分别讨论了光束灰度、光强振幅、信号光与背景光的有效Glass系数之比R对一维的光伏空间灰孤子宽度、横向总相移和横向运动速度的影响,并分析了光伏灰孤子的稳定性。当光束的灰度m为0时,这一理论可直接退化为光伏暗孤子的理论。 相似文献
13.
Hongcheng Wang 《Frontiers of Physics》2016,11(5):114204
This paper presents a theoretical analysis of the existence and stability of multi-peak solitons in parity–time-symmetric Bessel optical lattices with defects in nonlinear media. The results demonstrate that there always exists a critical propagation constant μ c for the existence of multi-peak solitons regardless of whether the nonlinearity is self-focusing or self-defocusing. In self-focusing media, multi-peak solitons exist when the propagation constant μ > μ c . In the self-defocusing case, solitons exist only when μ < μ c . Only low-power solitons can propagate stably when random noise perturbations are present. Positive defects help stabilize the propagation of multi-peak solitons when the nonlinearity is self-focusing. When the nonlinearity is self-defocusing, however, multi-peak solitons in negative defects have wider stable regions than those in positive defects. 相似文献
14.
《Photonics and Nanostructures》2014,12(4):340-349
We investigate the formation and propagation of bright and dark three-dimensional unstaggered spatial solitons with cylindrical symmetry in a nonlinear nanowire metamaterial. The metamaterial is formed by metallic nanowires embedded in a Kerr-type dielectric host and is modeled using an effective medium approach. Unlike conventional Kerr media, the metamaterial supports bright solitons when the host is a self-defocusing material and dark solitons when the host is a self-focusing material. Our numerical calculations show that the confinement of the spatial-solitons results from the interplay of the host nonlinear response strength and the hyperbolic dispersion of the photonic states in the nanowire array. Subwavelength solitary beams may be observed for sufficiently strong nonlinearities. 相似文献
15.
This paper predicts that bright-dark self-coupled vector solitons are possible in biased two-photon photovoltaic photorefractive crystals under steady-state conditions. The solutions of these vector solitons can be determined by use of simple numerical integration procedures. When the photovoltaic effect is neglectable, these vector solitons are bright-dark vector screening solitons. When the external bias field is absent, these vector solitons degenerate the bright-dark vector photovoltaic solitons. 相似文献
16.
Dumitru Mihalache 《Central European Journal of Physics》2008,6(3):582-587
A brief overview of recent theoretical results in the area of three-dimensional dissipative optical solitons is given. A systematic
analysis demonstrates the existence and stability of both fundamental (spinless) and spinning three-dimensional dissipative
solitons in both normal and anomalous group-velocity regimes. Direct numerical simulations of the evolution of stationary
solitons of the three-dimensional cubic-quintic Ginzburg-Landau equation show full agreement with the predictions based on
computation of the instability eigenvalues from the linearized equations for small perturbations. It is shown that the diffusivity
in the transverse plane is necessary for the stability of vortex solitons against azimuthal perturbations, while fundamental
(zero-vorticity) solitons may be stable in the absence of diffusivity. It has also been found that, at values of the nonlinear
gain above the upper border of the soliton existence domain, the three-dimensional dissipative solitons either develop intrinsic
pulsations or start to expand in the temporal (longitudinal) direction keeping their structure in the transverse spatial plane.
Presented at 9-th International Workshop on Nonlinear Optics Applications, NOA 2007, May 17–20, 2007, Świnoujście, Poland 相似文献
17.
We analyse surface solitons at the interface between a
one-dimensional photonic superlattice and a uniform medium with weak
nonlocal nonlinearity. We demonstrate that in deep lattices there
exist three kinds of surface solitons when the propagation constant
exceeds a critical value, including two on-site solitons and one
off-site soliton. These three kinds of surface solitons have unique
dynamical properties. If the relative depth of the superlattice is low,
there is only one kind of off-site soliton; however, the solitons of
this kind can propagate stably, unlike their deep superlattice
counterparts. Dipole surface solitons are also investigated, and the
stable domain is given. 相似文献
18.
In this study we report the first observation of spontaneous Raman solitons in stimulated Raman scattering (SRS) by the gas NH3. The scattered radiation is called Stokes radiation. Raman solitons are of considerable interest, because their existence can be explained by quantum-mechanical fluctuations of the electromagnetic field in vacuum. We have observed spontaneous Raman solitons in a forward SRS configuration for two different molecular transitions of NH3, the laser emissions at 58 μm and 72.6 μm wavelength. These are optically pumped by 10 μm CO2-laser pulses with a duration of 100 ns and an energy of 150 mJ. Spontaneous Raman solitons are short spikes in the pump pulse which occur during its depletion. Their origin is the rapid π phase change of the Stokes seed. In contrast to other laboratories we have used single-pass cells. Thus, we have succeeded in observing multiple spontaneous Raman solitons during one pump pulse. Previous experiments with multi-pass cells never showed multiple solitons. Since multiple spontaneous Raman solitons have already been reported in an earlier experiment with a single-pass cell filled with hydrogen at high pressure, we conclude that such multiple Raman solitons can be observed mainly in this type of gas cell. Subsequently, we have performed statistical measurements on the delay time and the height of the spontaneous Raman solitons in the depleted pump pulse for the 58 μm-NH3 emission. We have compared these statistics with theory and equivalent experimental results of other laboratories. They are in good agreement with the assumption that quantum-mechanical fluctuations are the origin of spontaneous Raman solitons. The most recent theories postulate that the origin of the formation of spontaneous Raman solitons can be explained by the rapid π phase change of the Stokes seed as well as that of the laser or polarization wave. Therefore, we have determined the phase of the spontaneous Raman solitons relative to the depleted pump pulse. Although, such changes of sign of the relative phase have already been observed in an earlier SRS experiment with hydrogen at high pressure, we did not detect any in our experiment. Therefore, we conclude that in this experiment the π phase change occurs in the Stokes or polarization wave. 相似文献
19.