首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 93 毫秒
1.
李书贤  徐文成  冯杰  刘颂豪 《光子学报》2008,37(10):1937-1941
研究了高阶色散和增益色散影响下,自相似脉冲在掺镱光纤放大器中的传输特性.从解析求解和数值模拟两方面分别阐述了初始脉冲能量、三阶色散和偶极子驰豫时间对脉冲传输质量的影响.结果表明,当传输考虑三阶色散效应时,伴随着脉冲啁啾非线性区域的扩大,啁啾中心随着色散系数取值的大小和正负前、后移动,脉冲峰向一侧延迟,中心位置发生漂移.增益色散对脉冲放大起到滤波作用,对自相似脉冲具有压窄效应.证实了具有一定驰豫时间的增益介质能够维持自相似孤子波的稳定传输.  相似文献   

2.
色散渐减光纤中自相似脉冲传输特性研究   总被引:7,自引:4,他引:3  
研究了在高阶色散影响下,自相似脉冲在具有正常色散的色散渐减光纤中的演化情况.结果表明:当考虑高阶色散的影响时,脉冲的啁啾仍然具有很强的线性特性,只是中心变得不对称,产生中心漂移.这种啁啾特性使得自相似脉冲在时域中的抛物线形状产生畸形,导致了脉冲峰向一边延迟,并使脉冲的中心位置漂移,同时伴随着脉冲边沿的振荡.但是通过采用色散补偿技术,自相似脉冲强的线性啁啾仍然可以得到高质量的飞秒量级压缩脉冲,与忽略三阶色散影响时得到的压缩脉冲的脉宽近似相等.  相似文献   

3.
以变系数耦合高阶非线性薛定谔方程为理论模型,采用分步傅里叶方法,讨论了孤子和艾里脉冲在光纤中的传输特性。研究表明三阶色散、自频移和自陡峭效应导致孤子和艾里脉冲所分离出的俘获孤子的中心位置发生偏移,且三阶色散会影响俘获孤子的强度,并讨论了两脉冲的中心位置及强度对艾里脉冲截断系数的依赖关系。  相似文献   

4.
本文利用激光脉冲在硅基光波导(SOI)中传播时满足的非线性薛定谔方程,采用分步傅里叶变换,数值模拟了硅基光波导中啁啾高斯脉冲在反常色散区的传播特性.通过模拟发现,三阶色散正负主要决定了脉冲的振荡波形性质,克尔效应与双光子吸收对脉冲波形起调制作用,自由载流子效应则可以忽略.初始啁啾参数的正负存在影响了脉冲的振荡强弱变化和脉冲中心的漂移的趋势,并且无论是正啁啾还是负啁啾,脉冲振荡与漂移都随着啁啾的增大而更加剧烈,同时啁啾正向增大与负向增大,都将导致脉冲展宽越严重致主峰峰值越低.  相似文献   

5.
负折射介质中三阶非线性色散项对超短脉冲传输的影响   总被引:1,自引:1,他引:0  
采用分步傅里叶法研究了三阶非线性色散项对超短脉冲传输的影响.通过模拟数值计算得出,在德鲁德模型频率选取的一定范围内,三阶非线性色散项对超短脉冲传输所造成的影响是不可忽略的.结果表明:三阶非线性色散项系数取负值时,在正常色散区超短脉冲不对称展宽,脉冲中心向前沿偏移;在零色散点超短脉冲不对称展宽程度加剧并在脉冲前沿形成振荡,脉冲中心向前沿偏移;在反常色散区超短脉冲不对称变窄,脉冲中心仍向前沿偏移.  相似文献   

6.
基于标准的非线性薛定谔方程,在增加高阶项的基础上(包括三阶色散、自频移、自陡峭和喇曼增益),采用分步傅里叶变换方法,分别讨论了各高阶效应对二阶怪波的传输特性的影响。结果表明,高阶效应的增加会使二阶怪波在传输过程中分裂得更快,其中三阶色散、自频移和喇曼增益对中心位置的二阶怪波几乎没有影响,但自陡峭效应会使中心位置的二阶怪波的幅度降低且中心发生偏移。  相似文献   

7.
单模光纤中三阶色散对超短光脉冲传输的影响   总被引:4,自引:0,他引:4  
刘群  励强华  牟艳秋 《光学技术》2006,32(1):148-150
基于超短光脉冲在单模光纤中传输时高阶非线性效应的影响。应用非线性薛定谔方程(HONLS)理论,考虑光纤色散三阶效应,推导出无啁啾的高斯脉冲沿光纤传输时脉冲变化的表达式,并对理论结果进行了数值模拟与分析。结果表明,三阶色散会引起光脉冲形状发生畸变,会在其前沿或后沿附近形成非对称的振荡结构。  相似文献   

8.
基于描述超短脉冲在超常介质中传输的非线性薛定谔方程,本文数值研究了高阶效应影响下高阶亮、暗孤子在超常介质中的传输情况。数值模拟表明,三阶色散和自陡峭效应都会引起高阶孤子的分裂和辐射,破坏高阶亮孤子周期性演化特性,导致高阶暗孤子分裂出的灰孤子不对称;孤子的阶数越高,三阶色散和自陡峭的影响越大。利用超常介质可控的色散和非线性特性,通过调节三阶色散和自陡峭效应的系数,发现超常介质中可以基本支持二阶亮孤子、二阶暗孤子和三阶暗孤子的稳定演化。本文的研究结果为将来进一步研究超常介质中高阶亮、暗孤子的存在及传输特性提供了一定的参考价值。  相似文献   

9.
王红英  刘红军  李小莉  赵卫 《光学学报》2007,27(7):338-1343
在设计宽带光学参变啁啾脉冲放大系统时,对色散源进行了理论分析和讨论。对光学参变啁啾脉冲放大系统的色散量以及各个过程中的高阶色散对脉冲时域和频域特性的影响进行了计算。结果表明展宽器引入了非常大的色散,放大器中信号光相位变化产生的色散较大,参量晶体本身引入的色散相对较小可以忽略不计。输出脉冲宽度主要受二阶色散影响,而三阶和四阶色散主要影响脉冲的波形和信噪比,对频域影响很小。  相似文献   

10.
受激喇曼散射对自相似脉冲产生的影响   总被引:2,自引:0,他引:2  
研究了在受激喇曼散射与三阶色散共同作用下,自相似脉冲在具有正常色散的色散渐减光纤中的演化情况.结果表明:在同一个传输距离上,当考虑受激喇曼散射与三阶色散的共同影响时,脉冲中心的不对称特性相对好转;产生中心漂移与边缘振荡较只有三阶色散作用时要减弱,啁啾仍然具有很强的线性特性,但是线性范围减小,导致频谱的窄化以及对接下来自相似脉冲的压缩产生了不利影响;而且光纤长度的延长并没有起到展宽啁啾线性范围的效果,反而导致严重的啁啾非线性;因此对脉冲进行压缩后,压缩脉冲质量较不考虑受激喇曼散射时要差.  相似文献   

11.
甘桂蓉  罗开基 《光学学报》2008,28(6):1041-1046
从修正的非线性薛定谔方程出发,采用变分法,导出了在高阶色散和五阶非线性共同作用情况下高斯型脉冲参量随传输距离的演化方程组;求出了振幅与脉宽、频率与啁啾、脉宽与啁啾之间的三个重要约束关系;并进一步得出了脉宽随传输距离演化的解析解和脉冲中心位置随传输距离的演化规律;描绘了高阶色散和五阶非线性下,脉宽随传输距离演化的图形.结果表明:光纤中的高阶色散和五阶非线性都会影响高斯型脉冲各个参量的演化,但脉宽和振幅间的绝热关系并未改变.高阶色散使高斯型脉冲的脉宽展宽,五阶非线性使高斯型脉冲的脉宽压缩,它们对脉宽或初始啁啾的影响可以在一定程度上抵消,从而有可能使脉冲近似实现保形传输.  相似文献   

12.
采用有限元法对实验室自制的非线性微结构光纤进行理论分析, 表明该光纤具有良好的非线性和色散波产生的相位匹配特性. 为实现微结构光纤非线性的全光纤化, 本实验采用中心波长为1032 nm的光纤飞秒激光器作为抽运源, 获得了753–789 nm 的近红外色散波. 实验中发现色散波中心波长和带宽随着抽运功率的改变会产生明显变化, 并且在不同光纤长度时, 色散波的频移量不同, 脉冲展宽及频谱也会有明显的变化. 实验结果与理论分析一致. 这些结果对实现微结构光纤非线性的全光纤化具有良好的借鉴作用, 为生物医疗应用特别是非线性光学显微成像术的近红外光源研究打下基础.  相似文献   

13.
We present new type of Dark-in-the-Bright solution also called dipole soliton for the higher order nonlinear Schrödinger (HNLS) equation with non-Kerr nonlinearity under some parametric conditions and subject to constraint relation among the parameters in optical context. This equation could be a model equation of pulse propagation beyond ultrashort range in optical communication systems. The solitary wave solution is composed of the product of bright and dark solitary waves. This type of pulse shape to be formed both the group velocity dispersion and third-order dispersion must be compensated. We also investigated the stability of the solitary wave solution under some initial perturbation on the parametric conditions. We have shown that the shape of pulse remains unchanged up to 20 normalized lengths even under some very small violation in parametric conditions.  相似文献   

14.
Pulse-width expansion and pulse-shape deformation of an ultrashort Gaussian pulse induced by both low and high order group velocity dispersion were theoretically analyzed in terms of energy conservation and coupled equations for three wave radiations. As an example, the optical parametric interaction processes in a negative uniaxial crystal of CsLiB6O10 with 50 fs of ultrashort Gaussian pulse were simulated. The results indicate that the degree of the pulse expansion induced by low and high order group velocity dispersion is determined by both the wavelength of the incident wave and the crystal length. A pulse could be expanded to 1.41 times its initial value as a crystal length equals the dispersion length and further heavily expanded with decreasing wave-length and increasing crystal length. The pulse expansion induced by high order group velocity dispersion using an incident wavelength of 213 nm is 1.6 times that when using 532 nm in a 50 fs pulse width without chirp modulation, and the symmetry deformation and the frequency pushing phenomena of the ultrashort pulse shape are also found. The text was submitted by the authors in English.  相似文献   

15.
光孤子传输中的高阶色散以及高次非线性效应是光纤通讯发展的重要制约因素。从光孤子在光纤中的一般传输方程出发, 在较大的入纤功率的前提下, 综合考虑了高阶色散、五次非线性和损耗因素, 得到其具体传输方程, 并据此从理论上分析了高阶色散和非线性对光孤子传输性能的影响。本文采用分步傅里叶方法, 以MATLAB为实现工具, 实现高阶色散和非线性对光孤子传输影响的模拟计算, 并深入分析了高阶色散和非线性导致的孤子脉冲频移现象。计算结果表明: 在入射功率较大的时候, 高阶色散效应不可忽略。当五次非线性γ2>0时,孤子脉冲主峰发生微小频移; 而当五次非线性γ2<0时, 孤子脉冲主峰基座产生微小频移; 当高阶色散β3>0时频率出现红移, 而当β3<0时, 频率出现蓝移。  相似文献   

16.
The passive nonlinear reshaping in normally dispersive optical fibers in the steady-state regime is studied numerically. It is found that normal dispersion and self-phase modulation are able to provide pulse reshaping towards a parabolic pulse profile at the distances exceeding the optical wave breaking length. However, as compared to the similariton formation in active fibers the resulted pulse shape in passive fibers is strongly depended on the initial pulse parameters and nonlinear and dispersive fiber properties as well. The influence of initial pulse shape, initial chirp, third-order dispersion and loss on the parabolic pulse formation is studied consistently, and estimation of practical conditions which are needed for parabolic pulses formation in a passive fiber is provided.  相似文献   

17.
The transmission equation of ultrashort optical pulse in the high-order dispersion media with the parabolic law (cubic–quintic) nonlinearity has been studied with the help of the subsidiary ordinary differential equation expansion method. As a result, the optical solitons and triangular periodic solutions are obtained, and the conditions for exact solutions to exist are also given.  相似文献   

18.
The effect of detuning from phase matching on the dynamics of a wave packet consisting of two unidirectional strongly interacting modes in a fiber with Kerr nonlinearity is considered. The effective parameters of dispersion and nonlinearity are analyzed for a wave packet that can be represented by a single partial pulse.  相似文献   

19.
五阶非线性下零色散附近的调制不稳定性   总被引:6,自引:2,他引:4  
胡涛平  罗青  颜森林  汪静 《光子学报》2008,37(7):1325-1328
在同时考虑光纤损耗、高阶色散以及高阶非线性情况下,从广义非线性薛定谔方程出发,研究了零色散附近的调制不稳定性,分析了四阶色散和五阶非线性对增益谱的影响.结果表明:当光脉冲工作在零色散附近时,四阶色散对调制不稳定性起决定作用,它使反常色散区的增益谱变宽.在光纤正常色散区,正(负)五阶非线性使增益谱的谱宽和峰值增大(减小);但在反常色散区,五阶非线性仅改变增益谱的峰值,几乎不影响谱宽.  相似文献   

20.
We numerically demonstrate the all-optical limiting features in a mismatched nonlinear directional coupler (NLDC) composed of a self-focusing and a self-defocusing waveguide for both continuous wave and pulse cases. The working conditions required are analyzed. To obtain the limiting feature, the propagation constant of the self-focusing waveguide should not be larger than that of the self-defocusing waveguide. Cascaded asymmetric NLDCs are investigated to improve the limiting characteristics. The limiting threshold and the limiting output power can be adjusted by varying the coupler length or the ratio of the nonlinearity coefficients of the self-defocusing and self-focusing waveguides. Analytical solutions are presented in the case of a continuous wave. For the pulse case, numerical solutions show that the top part of the output pulse, if it exceeds the limiting threshold, will be tailored, while the rising and falling edges of the output pulse are almost the same as the input pulse. There is almost no pulse breakup. The influence of the second order dispersion and the intermodal dispersion on the limiting characteristics are analyzed. PACS 42.79.Gn; 42.79.Ta  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号