掺钛蓝宝石激光器自锁模机制分析

掺钛蓝宝石自锁模激光器中产生自锁模的主要因素是自振幅调制（ＳＡＭ）、自相位调制（ＳＰＭ）和群速度色散（ＧＶＤ）。本文详细地分析了三要素在锁模脉冲形式的不同阶段所起的作用,指出在整个过程中自振幅调制对脉宽压缩起主要作用,而引入的适量负群速度色散在后期对ＳＰＭ效应与正ＧＶＤ起补偿作用,可获得最窄脉冲。最后,讨论了形成不稳定锁模脉冲的可能性。     

色散管理孤子群传输特性研究

从描述色散管理光孤子传输的非线性薛定谔（NLS）方程出发,利用对称分步傅里叶方法对方程进行数值 求解,模拟研究了色散管理孤子(DMS)在光纤中的传输演化特性。结果表明,孤子在通过周期性搭配具有相反色 散系数的光纤中传输,极大地降低了孤子间的相互作用,使得孤子的传输演化特性得到很大改善。指出了色散管 理孤子的优点以及在实际通信系统中的意义。     

Mixed breather-type and pure soliton solution of DNLS equation

A newly revised inverse scattering transform (IST) is used to solve the derivative nonlinear Schrödinger (DNLS⁺) equation with non-vanishing boundary condition (NVBC) and normal group-velocity dispersion, and a mixed type of soliton solution is found, which is composed of both pure and breather-type solitons. The mixed-soliton solution can degenerate into breathers and pure solitons when taking the limit of some special parameters, proving the validity of the mixed-type solution.     

飞秒孤子的传输与色散管理研究

从描述飞秒光孤子传输的高阶非线性薛定谔方程出发,采用对称分步傅里叶变换对方程进行数值求解,模拟了飞秒孤子在光纤通信系统中的传输演化特性。结果表明,合理地配置光纤系统,可以极大地改善孤子的传输演化特性,降低飞秒孤子间的相互作用,从而飞秒孤子在密集色散管理光纤系统中能够很好地传输。     

色散管理中的双孤子传输研究

本文采用分布傅立叶变换方法和数值方法研究了在周期扰动准理想色散管理系统中双孤子的传输,发现双孤子的传输和演化与扰动强度、扰动周期长度、三阶色散、孤子初始间隔等因素有关.     

含三阶色散的非线性薛定谔方程一个新的行波解

运用解析法求解含三阶色散光纤暗孤子的传输方程,得到孤子行波解,讨论含三阶色散光纤中暗孤子形成的条件以及三阶色散对暗孤子的中心位置、相位、振幅、频率的影响.     

Broadband SESAM for mode locked Yb:fiber lasers

We report a semiconductor saturable absorber mirror (SESAM) with phase shift compensation. The SESAM shows a uniform low-intensity reflectivity and a modulation depth up to 12% for the wavelength from 1000 to 1100 nm. A linear cavity all-normal dispersion Yb-doped fiber laser has proved its mode locking performance for the wavelength of both 1030 nm and 1064 nm.     

色散管理对初始啁啾孤子传输的影响

在色散管理孤子系统中引进初始啁啾这种扰动,根据非线性薛定谔（NLS）方程,利用对称分步傅立叶法对带初始啁啾光孤子在光纤中的传输情况进行了研究。结果表明,初始啁啾加强了光孤子间的相互作用,当啁啾达到一定程度时,孤子之间的作用变的相当剧烈,使得孤子发生严重形变,甚至导致孤子崩塌,这将对光孤子通信系统造成严重影响,而色散管理光纤系统可以有效地降低这些影响。     

色散和Kerr系数扰动影响下光孤子传输演化的研究

从描述色散位移光纤中Kerr系数随机扰动爱响下皮秒）光孤的修正非线性薛定锷（NLS）方程出发，利用对称分步Fourier方法，对光孤子在Kerr系数和群速度色散随机扰动情况下的传输演化特性进行了数值研究。结果表明，Kerr系数的随机扰动使单孤子幅值随传输距离产生了微小波动，对两孤子传输的影响主要表现在孤子间相互作用被加强，同时还表明，群速度色散的随机变化没有加强Kerr系数随机扰动对孤子间相互作用的影响，而是部分地互相抵消。     

利用密集色散缓变管理孤子消除全内反射光子晶体光纤中孤子的分裂与变形

提出了密集色散缓变管理孤子概念,给出了Compton散射下全内反射光子晶体光纤中孤子传输的非线性薛定谔方程,发现一定条件下,孤子对演变为准孤子对,幅值和宽度发生缓慢的周期性变化,未出现周期性离合现象.提出了用CSDMS消除孤子分裂和变形的新方法.     

用协同学的观点研究锁模激光脉冲的建立过程

该文用协同学的观点研究锁模激光脉冲的建立过程,认为锁模激光脉冲的建立过程是非线性的合作效应或者是自组织现象.从模式表象的激光方程出发,导出了锁模激光方程以及相应的福克-普朗克方程,得到了锁模激光的第一阈值和第二阈值.最后讨论了锁模激光光束质量的最佳条件,即在Dm≈1.5 Dthr.1时为获得高光束质量的锁模激光的最佳参数选择,计算结果与实验基本一致.     

光纤通信系统中非相干暗孤子间的相互作用

利用变分法，通过非线性Schroedinger方程，导出光通信系统中非相干暗孤子间的相互作用，即通过非线性强度叠加产生的相互作用。结果表明：在两个非相干暗孤子之间存在排斥力，并且高阶色散效应减弱了非相干暗孤子的相互作用。这与相干暗孤子之间的相互作用结果一致。     

Formation and propagation of matter-wave soliton trains

Attraction between the atoms of a Bose-Einstein condensate renders it unstable to collapse, although a condensate with a limited number of atoms can be stabilized by confinement in an atom trap. However, beyond this number the condensate collapses. Condensates constrained to one-dimensional motion with attractive interactions are predicted to form stable solitons, in which the attractive forces exactly compensate for wave-packet dispersion. Here we report the formation of bright solitons of (7)Li atoms in a quasi-one-dimensional optical trap, by magnetically tuning the interactions in a stable Bose-Einstein condensate from repulsive to attractive. The solitons are set in motion by offsetting the optical potential, and are observed to propagate in the potential for many oscillatory cycles without spreading. We observe a soliton train, containing many solitons; repulsive interactions between neighbouring solitons are inferred from their motion.     

平脉动孤波传输特性的研究

基于五次复系数Ginzburg-Landau方程,对平脉动孤波的传输特性进行了详细的研究,研究表明:平脉动孤波的传输特性对高阶非线性效应非常敏感,即使某参数改变很小的值,也会改变其周期特性;此外,一定值的三阶色散可以消除平脉动孤波的周期特性,使它变为形状保持不变的孤子继续传输;最后,当两相邻平脉动孤渡的间距小到一定程度时,它们之间就会产生强烈的相互作用,且采用不等相位输入法可以很好抑制这种相互作用,使两脉冲保持稳定的传输.     

含高阶色散的双折射光纤孤子传输特性研究

研究含高阶色散的双折射光纤中孤子的传输特性,导出高阶色散双折射光纤中光脉冲形成束缚态的振幅阈值条件和双分量孤子的有效相互作用能,讨论了高阶色散对双折射光纤中光脉冲形成束缚态的振幅阈值和双分量孤子有效相互作用能的影响.     

半导体激光器中产生的光脉冲红移啁啾的消除

对啁啾脉冲在单模线性色散光纤中的非线性传输演化过程进行了解析分析和定量的数值计算．结果表明,在单模线性色散光纤正群速色散区,用输入光脉冲产生的兰移啁啾可以消除半导体激光器中产生的光脉冲红移啁啾     

非线性非局域光格子中的高阶光学模式及其稳定性

讨论了非线性非局域光格子中奇、偶及其各类高阶光孤子的能流随传输常数的变化,特别讨论存在于非线性非局域光格子中的第三、第四扭转孤子的高阶光学模式,并从中分析了孤子振幅随格子调制深度p和线性非局域响应参数d的变化趋势.同时利用线性稳定性方法讨论它们的稳定性,结果表明,它们的不稳定范围有所扩大.由于光格子对全光控制技术有着潜在的应用价值,所以这些结果可以为未来全光控制技术提供最新的理论依据.     

Numerical analysis of mode locking in multi-core photonic crystal fiber

With linearly coupled nonlinear Schrodinger equations, numerical analysis has been performed on the mode locking forming pro-cedure of a fiber laser in the linear cavity configuration. The fiber is Yb-doped multi-core photonic crystal fiber and semiconductor saturable absorber mirror (SESAM) is adopted as the nonlinear transmission element to start mode locking. Because of the noise randomness, initial pulse would be picked out by SESAM in one or more cores which makes the multi-core mode locking quite different from single-core one. The two situations are compared and fully discussed. Mode locking in multi-core photonic crystal fiber laser can be realized only if the couple coefficient between the cores and the temporal overlap between the pulses in different cores are large enough.     

大动脉血管壁应力孤立波

在人体正常生理条件下,血管内的扰动将以应力波的形式传播.讨论了大动脉血管壁应力波的传播问题,得到了描述血管壁运动的非线性方程,分析了其线性近似下的色散关系.该非线性方程在低阶近似下演化为KdV方程,这说明在大动脉血管中存在孤立波,最后给出了该孤立波解并讨论了其实际意义.     

Observation of random-phase lattice solitons

The coherence of waves in periodic systems (lattices) is crucial to their dynamics, as interference effects, such as Bragg reflections, largely determine their propagation. Whereas linear systems allow superposition, nonlinearity introduces a non-trivial interplay between localization effects, coupling between lattice sites, and incoherence. Until recently, all research on solitary waves (solitons) in nonlinear lattices has involved only coherent waves. In such cases, linear dispersion or diffraction of wave packets can be balanced by nonlinear effects, resulting in coherent lattice (or 'discrete') solitons; these have been studied in many branches of science. However, in most natural systems, waves with only partial coherence are more common, because fluctuations (thermal, quantum or some other) can reduce the correlation length to a distance comparable to the lattice spacing. Such systems should support random-phase lattice solitons displaying distinct features. Here we report the experimental observation of random-phase lattice solitons, demonstrating their self-trapping and local periodicity in real space, in addition to their multi-peaked power spectrum in momentum space. We discuss the relevance of such solitons to other nonlinear periodic systems in which fluctuating waves propagate, such as atomic systems, plasmas and molecular chains.