Small Amplitude Solitons in the Higher-Order Nonlinear Schroedinger Equation in an Optical Fibre

By taking advantage of the approximate approach of small amplitude soliton, we study the higher-order nonlinear Schroeinger equation in an optical fibre. Our results show that the bright and dark solitons of small amplitude can appear on the background of a continuous wave in normal dispersion regime or in anomalous dispersion regime simultaneously due to the higher-order effects. Interesting connection between the higher-order nonlinear Schroedinger equation and the Korteweg-de Vries equation is also demonstrated.     

推导光栅衍射暗纹位置公式的简易方法

光栅衍射是普通物理等物理类教材中重要的必修内容．常用的普通物理教材对光栅衍射规律的描述通常忽略推导过程而只给出一些重要的结论,例如暗纹位置公式;或者仅作定性分析,例如明条纹宽度随缝数增多而变窄等．事实上,对于光栅衍射暗纹位置公式可以由振幅矢量法求解,     

Dynamical Stability of Gap Soliton of One-Dimensional Condensate in Optical Lattices with Strong Interatomic Interaction

By developing the multiple scales method, we analytically study the dynamics properties of gap soliton of Bose- Einstein condensate in optical lattices. It is shown that the gap soliton will appear at Brillouin zone edge of linear band spectrum of the condensates when the interatomic interaction strength is larger than the lattice depth. Moreover, the density of gap soliton starts to be relatively small, while it increases with time and becomes stable.     

Small Amplitude Solitons in Bose--Einstein Condensates with External Perturbation

By developing a small amplitude soliton approximation method, we study analytically weak nonlinear excitations in cigar-shaped condensates with repulsive interatomic interaction under consideration of external perturbation potential. It is shown that matter wave solitons may exist and travel over a long distance without attenuation and change in shape by properly adjusting the strength of interatomic interaction to compensate for the effect of external perturbation potential.     

Gain/loss effect on bright solitary wave in a cigar-shaped attractive condensate in the presence of expulsive parabolic potential

<正>Taking into account both gain/loss and time-dependent atomic scattering length,this paper analytically derives an exact bright solitary wave in a cigar-shaped attractive condensate in the presence of an expulsive parabolic potential. Due to the balance of the scattering length and gain/loss,the bright solitary wave is shown to have constant amplitude. Especially,it is found that the bright solitary wave is accelerated by expulsive force,whose velocity can be modulated by changing the axial and transverse angular frequencies.The results are in good agreement with the experimental observations by Khaykovich et al(2002 Science 296 1290).