Zero-n gap soliton

Periodic structures consisting of alternating layers of positive-index and negative-index materials have a novel bandgap at the frequency at which the average refractive index is zero. We show that, in the presence of a Kerr nonlinearity, this zero-n gap can switch from low transmission to a perfectly transmitting state, forming a nonlinear resonance or gap soliton in the process. This zero-n gap soliton is omnidirectional, in contrast to the usual Bragg gap soliton of positive-index periodic structures.     

一类两维光学格子中稳定的复合孤子

对两维光学格子中非线性薛定谔方程一类新的稳态解做了数值分析，发现其在传播过程中逐渐衰变为一种稳定的复合孤子，孤子的两分量在传播过程中不断交换能量，总能量守恒. 关键词： 稳态解 两维格子 孤子     

Enhanced soliton transport in quasiperiodic lattices with introduced aperiodicity

We study linear transmission and nonlinear soliton transport through quasiperiodic structures, where the lattice profiles are described by multiple modulation frequencies. We show that resonant scattering at mixed-frequency resonances limits transmission efficiency of localized wave packets, leading to radiation and possible trapping of solitons. We obtain an explicit analytical expression for optimal quasiperiodic lattice profiles, where additional aperiodic modulations suppress mixed-frequency resonances, resulting in dramatic enhancement of soliton mobility. Our results can be applied to the design of photonic waveguide structures, and arrays of magnetic micro-traps for atomic Bose-Einstein condensates.     

(2+1)维非线性KdV方程的新孤子结构

通过选取另一类种子解，给出了(2+1)维非线性KdV方程的一类变量分离新解.适当地选择变量分离新解中的任意函数和条件函数，揭示了一类新型孤子结构，如周期性孤波结构、环状孤子结构、曲线型孤子结构等.可以发现(2+1)维非线性KdV方程存在的这类新型孤子结构，是无法通过以往文献中给出的通用变量分离表达式得到的，而且这类新型孤子结构对于实际自然现象的解释有积极的意义. 关键词： 变量分离法 (2+1)维非线性KdV方程 新孤子结构     

Ratchet-induced matter-wave transport and soliton collisions in Bose-Einstein condensates

We study the dynamics of bright matter-wave solitons in a Bose-Einstein condensate with negative scattering length under the influence of a time-periodic ratchet potential. The potential is formed by a one-dimensional bichromatic optical lattice which flashes on and off so that the time average of its amplitude vanishes. Due to the broken space and time-reversal symmetries of the potential, the soliton is transported with a nonzero average velocity. By employing the non-dissipative mean-field model for the matter waves, we study the dependence of the transport velocity on the initial state of the soliton and show how the properties of the individual localized states affect the outcome of their collisions. A useful insight into the transport properties is provided by Hamiltonian theory for the mean field, which treats the extended matter-wave excitation as an effective classical particle.     

Controllable soliton emission from a Bose-Einstein condensate

We demonstrate, through numerical simulations, the controllable emission of matter-wave bursts from a Bose-Einstein condensate in a shallow optical dipole trap. The process is triggered by spatial variations of the scattering length along the trapping axis. In our approach, the outcoupling mechanisms are atom-atom interactions and thus, the trap remains unaltered. Once emitted, the matter wave forms a robust soliton. We calculate analytically the parameters for the experimental implementation of these matter-wave bursts of solitons.     

Packing, unpacking, and steering of multicolor solitons in optical lattices

We discuss potential applications of multicolor solitons supported by periodic lattices imprinted in quadratic nonlinear media. Such lattice solitons can be packed together with appropriate relative phases to form stable soliton trains that can be treated as bit sequences. We describe controllable splitting of the trains into their soliton constituents and the angle- and power-controlled steering and trapping of solitons moving across the lattice into the desired guiding channel.     

Non-autonomous matter-wave solitons in hybrid atomic–molecular Bose–Einstein condensates with tunable interactions and harmonic potential

In this paper, we investigate matter-wave solitons in hybrid atomic–molecular Bose–Einstein condensates with tunable interactions and external potentials. Three types of time-modulated harmonic potentials are considered and, for each of them, two groups of exact non-autonomous matter-wave soliton solutions of the coupled Gross–Pitaevskii equation are presented. Novel nonlinear structures of these non-autonomous matter-wave solitons are analyzed by displaying their density distributions. It is shown that the time-modulated nonlinearities and external potentials can support exact non-autonomous atomic–molecular matter-wave solitons.     

A novel system for optically localized soliton pulse in a nano-waveguide

We propose a novel optical system that can be used to trap (store) light coherently. The system consists of two micro and a nano-ring resonators that can be integrated into a single system, which can be employed to generate the large bandwidth by a soliton pulse within a Kerr type nonlinear medium. The balance between dispersion and nonlinear lengths of the soliton pulse exhibits the soliton behavior known as self-phase modulation, which introduces the optical output (i.e. gain) constant, which means that light pulse can be trapped, i.e. localized coherently within the nano-waveguide. The time independent soliton pulse is adiabatically localized within the nano-ring device. Results obtained have shown that the trapping of the localized temporal and spatial soliton pulses is achieved.     

Parametric amplification of soliton steering in optical lattices

We report on the effect of parametric amplification of spatial soliton swinging in Kerr-type nonlinear media with longitudinal and transverse periodic modulation of the linear refractive index. The parameter areas are found where the soliton center motion is analogous to the motion of a parametrically driven pendulum. This effect has potential applications for controllable soliton steering.     

外势场作用下的玻色-爱因斯坦凝聚啁啾孤子的演化与操控

提出了一种处理玻色-爱因斯坦凝聚啁啾孤子动力学的拓展变分方法,深入研究了玻色-爱因斯坦凝聚孤子在周期势与抛物势联合作用下的动力学演化,利用拓展变分法给出了解析处理,并和基于分步傅里叶变换的直接数值法进行比较,发现这种拓展变分方法能够充分揭示上述外势场中的玻色-爱因斯坦凝聚啁啾孤子的动力学行为和特征．同时给出了能支持多稳定晶格囚禁玻色-爱因斯坦凝聚啁啾孤子的周期势与抛物势强度比值的临界值和一种通过控制外势场可有选择地移动玻色-爱因斯坦凝聚啁啾孤子的操控方法,这为玻色-爱因斯坦凝聚的实验和应用研究提供了理论参 关键词： 玻色-爱因斯坦凝聚 Gross-Pitaevskii方程 啁啾孤子 操控     

Evolutions of matter-wave bright soliton with spatially modulated nonlinearity

The evolution characteristics of a matter-wave bright soliton are investigated by means of the variational approach in the presence of spatially varying nonlinearity. It is found that the atom density envelope of the soliton is changed as a result of the spatial variation of the s-wave scattering length. The stable soliton can exist in appropriate initial conditions. The movement of the soliton depends on the sign and value of the coefficient of spatially modulated nonlinearity. These theoretical predictions are confirmed by the full numerical simulations of the one-dimensional Gross-Pitaevskii equation.     

A new soliton communication band for optical networking redundancy using a Gaussian soliton generation

We present a novel communication band of the tunable multi-Gaussian soliton system, whereas the large bandwidth signals of the spatial soliton pulses can be generated after propagating within the nonlinear ring resonator system. A Gaussian pulse input with 20 ns pulse width, 2 W peak power, the center wavelength at 1300 nm is propagated into the nonlinear ring resonator system. Using the appropriate parameters relating to the practical device such as micro-ring radii, coupling coefficients, linear and nonlinear refractive index, we found that the multi-soliton pulse obtained have shown the potential of application for a new dense wavelength division multiplexing (DWDM) band. The soliton pulse width and free spectrum range of 400 and 7 fm are obtained, respectively, which can be used to increase the channel capacity in soliton communication. Furthermore, the soliton power obtained is available for system and link redundancy, where the output soliton power of 12 W is achieved.     

Multitweezers generation using dark soliton pulses and applications

Multi-dark soliton pulses have been successfully generated by using forward and backward pumping of the S-band erbium doped fiber in the fiber optic loop, where the Stimulated Brillouin Scattering (SBS) is a nonlinear interaction between pump fields with Stokes field through acoustic wave. Results obtained have shown that the dark soliton trains can be generated and configured as the multi-optical tweezers. The advantage is that the generated tweezers are in the form of dynamic tweezers, where they can transmit/transport via the soliton communication link. The single dark soliton is also experimentally generated by using the different fiber optic scheme. We have also theoretically shown that the dynamic tweezers can be controlled and tuned, which is available for trapping and transportation in the communication link via a wavelength router. The quantum states of the transported atoms/molecules by the dynamic tweezers can be performed by using the quantum processing unit incorporating in the system.     

Exact periodic wave and soliton solutions in two-component Bose--Einstein condensates

We present several families of exact solutions to a system of coupled nonlinear Schr\"{o}dinger equations. The model describes a binary mixture of two Bose--Einstein condensates in a magnetic trap potential. Using a mapping deformation method, we find exact periodic wave and soliton solutions, including bright and dark soliton pairs.     

Vibrating and shaking soliton pairs in dissipative systems

We show that two-soliton solutions in nonlinear dissipative systems can exist in various forms. As with single solitons, they can be stationary, periodic or chaotic. In particular, we find new types of vibrating and shaking soliton pairs. Each type of pair is stable in the sense that the bound state exists in the same form indefinitely.     

准光孤子特性及其通信技术研究

对准光孤子理论进行了研究，用一个合适的、持续的色散管理方法，从一个修正的非线性薛定谔方程得到一个精确解，用这个解构造一个非线性稳定的准光孤子脉冲。用数值模拟的方法得出了准光孤子和光孤子的波形。结果表明：准光孤子几乎具有光孤子的全部优点，其脉冲宽度比光孤子要小很多，并且准光孤子的脉冲宽度可以通过调节光纤的结构参数来进行调整，准孤子能够在光纤中稳定地实现长距离传输，而且能够很好地克服由孤子的固有特性造成的对通信容量的限制，所以准光孤子有望成为下一代通信系统的最佳信号载体。     

Experimental observation of oscillating and interacting matter wave dark solitons

We report on the generation, subsequent oscillation and interaction of a pair of matter-wave dark solitons. These are created by releasing a Bose-Einstein condensate from a double well potential into a harmonic trap in the crossover regime between one dimension and three dimensions. Multiple oscillations and collisions of the solitons are observed, in quantitative agreement with simulations of the Gross-Pitaevskii equation. An effective particle picture is developed and confirms that the deviation of the observed oscillation frequencies from the asymptotic prediction nu(z)/sqrt 2, where nu(z) is the longitudinal trapping frequency, results from the dimensionality of the system and the soliton interactions.     

拉曼增益对高双折射光纤中暗孤子俘获的影响

从高双折射光纤中含有拉曼增益的耦合非线性薛定谔方程出发, 利用拉格朗日方法, 推导出了暗孤子俘获的阈值, 并利用快速分步傅里叶变换, 模拟了孤子的两个正交偏振分量的演化, 对比了两种方法得到的阈值, 探究了暗孤子俘获受拉曼增益的影响. 研究发现解析解所得阈值比数值解偏小, 且群速度失配越小时, 二者符合得越好; 并且拉曼增益减小了暗孤子的俘获阈值, 当平行拉曼增益增大时, 俘获阈值减小加快.     

Spontaneous soliton formation and modulational instability in Bose-Einstein condensates

The dynamics of an elongated attractive Bose-Einstein condensate in an axisymmetric harmonic trap is studied. It is shown that density fringes caused by self-interference of the condensate order parameter seed modulational instability. The latter has novel features in contradistinction to the usual homogeneous case known from nonlinear fiber optics. Several open questions in the interpretation of the recent creation of the first matter-wave bright soliton train [Nature (London) 417, 150 (2002)]] are addressed. It is shown that primary transverse collapse, followed by secondary collapse induced by soliton-soliton interactions, produces bursts of hot atoms at different time scales.