三阶色散影响下二阶孤子间互作用及抑制

在色散位移光纤中，研究了三阶色散影响下同相和反相二阶孤子之间的互作用，分析了同相和反相二阶孤子对衰变后时域波形和频域频移的变化，发现三阶色散使二阶孤子分裂出一大一小两个不同振幅的基阶孤子，并彼此分离，但孤子对中心频率频移量却减小。通过采用非线性增益控制的方法可以有效抑制二阶孤子间的互作用，使孤子保型传输而不发生衰变。同时通过周期性改变三阶色散系数，可以减小三阶色散的不利影响，抑制孤子中心频率的频移，使孤子对不偏离原来时间槽，稳定孤子传输。     

高阶孤子在光纤中传输的数值研究

通过数值求解非线性薛定谔方程,得到了二阶和三阶孤子的传输特性,并和一阶孤子做了比较.对于二阶孤子和三阶孤子间的相互作用做了分析,讨论了三阶色散对高阶孤子相互作用的影响,得出随着三阶色散的增大,会使孤子的衰变具有新的特性,将会导致光孤子通信的误码率加大.     

拉曼增益对双折射光纤中孤子传输特性的影响

本文采用考虑拉曼增益的耦合非线性薛定谔方程,利用分步傅里叶方法求解并仿真模拟了光孤子脉冲在不同性质的双折射光纤中传输时的演化过程.结果表明,拉曼增益可以有效抑制非线性耦合导致的孤子漂移,同时会导致光孤子脉冲峰值在传输时不断增大,产生拉曼放大效应.拉曼增益也可以有效抑制双折射光纤中传输的相邻光孤子之间的相互作用.     

光纤通信中光孤子的传输特性分析

计算机模拟技术已经广泛应用在教学和科研中,在光纤通信课程教学中引入MATLAB语言,形象的给出光波在光纤中传输的模拟结果,既形象又深刻.以光孤子为例,给出基态孤子,二阶孤子和三阶孤子传输特性以及两个基态孤子的相互作用.     

超短激光脉冲在等离子体中的分裂以及类孤子结构的形成

用一维粒子模拟研究了超短脉冲在等离子体中传播时产生的光孤子结构以及由此形成的脉冲分裂现象，比较了不同峰值强度和脉冲宽度对形成光孤子以及脉冲传播方式的影响.研究表明: 脉冲宽度在若干个到十几个振荡周期的超短脉冲在等离子体中可能形成高速传播的光孤子；脉冲宽度增加和强度增大两种方式都可以使得孤子结构的传播速度减慢,且由于高阶孤子的衰变使得初始激光脉冲在等离子体中发生分裂，形成两个以不同速度向前传播的孤子结构.由孤子阶数的理论计算可较好地预言激光脉冲在等离子体中分裂的子脉冲数. 关键词： 光孤子 超短激光脉冲 等离子体 粒子模拟     

空间光孤子脉冲在平面光波导中的传输

分析研究了空间光孤子脉冲化后在反常群速色散的克尔非线性平面光波导中的传输特性和稳 定性.当空间光孤子脉冲的时间宽度等于某一临界值时，脉冲发生自陷，小于该值时，脉冲 发生扩散，大于该值时，脉冲发生塌陷.空间光孤子的阶数越高，这个临界值越小.当空间光 孤子脉冲的时间宽度等于某一特定值时，脉冲塌陷最快，与这个特定值相差越大，塌陷越慢 .空间光孤子的阶数越高，这个特定值越小.脉冲自陷后的峰值光强、时间和空间宽度与输入 时的值有明显的不同. 关键词： 脉冲自陷 脉冲塌陷 光孤子     

随机双折射对光孤子传输影响的研究

利用对称分步傅里叶法,数值模拟了光孤子在双折射光纤中的传输特性,分析了孤子脉冲两正交偏振分量的群速度失配对孤子传输产生的影响.结果表明,当光纤的双折射较小时,两偏振分量的脉冲强度变化不大,孤子基本能够保形传输;当光纤的双折射较大时,两偏振分量脉冲很快展宽,强度迅速减小,孤子不能够保形传输;如果光纤的双折射具有随机性,孤子传输的两偏振分量脉冲强度会随着传输距离有强弱不规则的变化,但是两偏振分量的强度变化互相补充,合成强度没有太大的变化,孤子能够稳定的传输;孤子间没有相互作用影响的传输距离随着光纤随机双折射偏振分量群速失配的增大而变小;通过选择恰当的振幅比,传统的不等振幅法仍然能够有效地抑制孤子间的相互作用.     

光通信 光传输、通信理论

TN911 2005032178 二阶孤子间相互作用引起孤子衰变=Solicon decay in- duced by interaction between two neighboring second-order solitons[刊,中]／苗润才(陕西师范大学物理学与信息技术 学院．陕西,西安(710062)),王飞…∥光于学报．-2004, 33(8).-927-930 对于二阶孤子脉冲对,通过数值求解非线性 Schrodinger方程,得到了二阶孤子在光纤中传输时的衰变 规律。由于脉冲之间的相互作用,原来的二阶孤子衰变为     

随机双折射对光孤子传输影响的研究

利用对称分步傅里叶法,数值模拟了光孤子在双折射光纤中的传输特性,分析了孤子脉冲两正交偏振分量的群速度失配对孤子传输产生的影响.结果表明,当光纤的双折射较小时,两偏振分量的脉冲强度变化不大,孤子基本能够保形传输|当光纤的双折射较大时,两偏振分量脉冲很快展宽,强度迅速减小,孤子不能够保形传输|如果光纤的双折射具有随机性,孤子传输的两偏振分量脉冲强度会随着传输距离有强弱不规则的变化,但是两偏振分量的强度变化互相补充,合成强度没有太大的变化,孤子能够稳定的传输|孤子间没有相互作用影响的传输距离随着光纤随机双折射偏振分量群速失配的增大而变小|通过选择恰当的振幅比,传统的不等振幅法仍然能够有效地抑制孤子间的相互作用.     

脉冲内拉曼散射影响下的孤子之间的相互作用及其控制

研究了脉冲内拉曼散射效应影响下的同相和反相相邻孤子脉冲之间的相互作用,分析了孤子之间的相互作用对定时抖动的影响和脉冲内拉曼散射效应对孤子频移的影响。研究结果表明:在脉冲内,在拉曼散射效应的影响下,同相基态孤子脉冲的周期性离合被破坏了,两孤子脉冲一次碰撞后一直处于排斥状态,并且在碰撞后自频移现象十分明显;反相孤子脉冲的影响则较弱,两孤子脉冲都向下降沿发生偏移。引入非线性增益可以有效地控制孤子之间的相互作用,抑制自频移效应和稳定孤子传输。     

Soliton interaction in logarithmically saturable media

An analysis, based on the variational approach, is carried out of the interaction between two fully coherent solitons as well as two partially coherent soliton stripes in a medium with logarithmic nonlinearity. For the coherent case, it is found that the interaction can be both attractive and repulsive depending on the relative phase. The different interaction scenarios involve a bound system where the distance between the solitons oscillates with various magnitude of the oscillation amplitude, including total coalescence, and another where the solitons separate asymptotically. The effect of partial coherence on the soliton interaction is also studied by analyzing the interaction between two partially coherent soliton stripes. It is found that the strength as well as the character (attractive/repulsive) of the interaction changes for decreasing coherence. Thus, the general interaction properties of solitons in logarithmic nonlinear media are qualitatively similar to those of solitons in nonlinear Kerr media.     

含自频移啁啾超短脉冲间相互作用的数值研究

采用拟解法给出了Ginzberg—Landau方程类孤波解的参数表达式.通过数值模拟对啁啾超短脉冲间的相互作用进行了研究．结果表明, 随着相邻孤子间距离的减小,它们之间的相互作用变得越来越严重．传统的不等振幅法在一定程度上可以抑制孤子间的相互作用,通过选取合适的振幅比,找到了相邻孤子间相互作用平衡的最小距离,这对提高光纤传输的比特率具有十分重要的意义．讨论了多孤子间的相互作用,找到了抑制四孤子之间相互作用的合适振幅比．     

非对称光折变全息空间光孤子的存在曲线

证明了在加外电场的光折变晶体中存在非对称全息空间光孤子对，其特征是孤子对中的两个 孤子具有相同的宽度、不同的振幅.给出了这种孤子对的存在曲线，其中存在三个具有不同 特征的区域：对于给定的外加电场来说，当孤子对中两个孤子的入射峰值强度之和与背景光 强度之比足够大或者足够小时，孤子宽度强烈依赖于这个比值，而在此中间的一段区域，孤 子宽度几乎不随这个比值而变化.非对称情况下这个中间区域的范围比对称情况的窄. 关键词： 空间光孤子 光折变非线性光学 全息光栅     

Peregrine solitons and algebraic soliton pairs in Kerr media considering space–time correction

Exact unified rational solutions describing a family of Peregrine solitons as well as related algebraic soliton pairs in either self-focusing or self-defocusing Kerr media are presented, with distinct defining regimes and an explicit relationship for those of opposite nonlinearity. The active role of the space–time correction effect that plays in these soliton species is highlighted, leading to unique dynamics such as the persistence of Peregrine solitons in a defocusing Kerr medium, the availability of giant peak amplitude for the bright–bright soliton pair, and the existence of so-called bright–dark soliton pair. The evolution dynamics of the algebraic two-soliton state toward a spliced single soliton is also discussed.     

Separate spatial soliton pairs in a biased series centrosymmetric photorefractive crystal circuit

It is shown theoretically that three types of separate soliton pairs: bright-bright, bright-dark, and dark-dark, can be established in a biased series circuit consisting of two centrosymmetric photorefractive crystals and the two solitons in a separate soliton pair can affect each other by the light-induced current. The effects of the intensities of soliton beams and background lights on the normalized profiles of solitons are discussed.     

PARTICULAR SOLITONS IN NONLINEAR LATTICE

One soliton of particle velocity and its amplitude (maximum particle velocity of one soliton) in Toda lattice is given analytically. It has also been known numerically that the maximum particle velocity (when the collision of two solitons reaches their maximum, we define V_n at this time as its maximum particle velocity) during the collision of two solitons moving in the same direction is equal to the difference between the amplitudes of two solitons if the difference is large enough; however, the maximum particle velocity is equal to the adding up of the amplitudes of two solitons moving in the opposite directions. The relationship between the maximum value of e^-(r_n)-1 and their initial amplitude of e^-(r_n)-1 is also given analytically in Toda lattice if the amplitudes of the two solitons are the same and their moving directions are opposite. Compared with the Boussinesq equation, there are differences between the Toda lattice equation and the Boussinesq equation for solitons during the collision.     

Separate holographic screening soliton pairs in a biased series photorefractive crystal circuit

Holographic dark (bright) screening solitons are predicted in one dimension for a series circuit consisting of two photorefractive crystals connected electronically by electrode leads in a chain with a voltage source. Each crystal can support a holographic screening soliton. The two solitons are known collectively as a separate holographic screening soliton pair with three types: bright--bright, bright--dark and dark--dark. The numerical results show that the two solitons in a soliton pair can affect each other through a light-induced current and their coupling can affect their spatial profiles under the limit in which the optical wave has a spatial extent much less than the width of the crystal.     

光诱导平面波导阵列中离散空间光孤子的相干相互作用

采用Petviashvili迭代法对光诱导平面波导阵列中的一维离散空间光孤子进行求解,利用分步束传播法对离散空间光孤子间的相干相互作用进行了详细的数值模拟.探讨了离散孤子间的相位差、孤子光强、波导阵列写入光的强度和周期以及外加电场对相互作用过程的影响.结果表明：离散孤子间的相位差对相互作用的影响与连续介质中的情况类似,不同相位差情况下的相互作用也表现为吸引、排斥以及能量转移等现象.同时,离散孤子间的相干相互作用过程(如融合距离和排斥间距等)均会受到孤子光强、波导阵列写入光的强度和周期以及外加电场大小的影响 关键词： 光诱导平面波导阵列 离散空间光孤子 相干相互作用     

Anomalous interactions of spatial gap solitons in optically induced photonic lattices

We demonstrate coherent interactions between spatial gap solitons in optically induced photonic lattices. Because of the "staggered" phase structures, two in-phase (out-of-phase) bright gap solitons can repel (attract) each other at close proximity, in contrast to soliton interaction in homogeneous media. A reversal of energy transfer direction and a transition between attractive and repulsive interaction forces can be obtained solely by changing the initial soliton separation relative to the lattice spacing.     

Dark and anti-dark vector solitons of the coupled modified nonlinear Schrödinger equations from the birefringent optical fibers

Coupled modified nonlinear Schr?dinger (CMNLS) equations describe the pulse propagation in the picosecond or femtosecond regime of the birefringent optical fibers. A new type of the Lax pair and another hierarchy of the infinitely many conservation laws are derived based on the Wadati-Konno-Ichikawa system. By means of the Hirota method, soliton solutions in the normal dispersion regime are obtained. Parametric regions for the existence of dark and anti-dark vector soliton solutions are given. Asymptotic analysis shows that the collision between two solitons (two anti-dark solitons, two dark solitons, or dark and anti-dark solitons) in each polarization direction is elastic. Moreover, there is no energy transfer between two polarization components of each vector soliton, whether dark or anti-dark vector soliton. In addition, dark and anti-dark solitons can coexist on the same background seen from the collision between the dark and anti-dark solitons in one polarization direction. Our graphical analysis shows that the parameters in the CMNLS equations not only determine the regions for the existence of dark and anti-dark soliton solutions but also control the phase and direction of the propagation of the solitons. Finally, through the linear stability analysis, the modulational instability condition is given.