色散管理光纤中超短光脉冲压压缩效应研究

本文研究了色散管理光纤中超短光脉冲的压缩效应。对于两种不同的色散管理光纤，分析了脉冲压缩机制和效果。发现总色散为零和总色散不为零的色散管理光纤对超短光脉冲压缩都有较大的压缩比，而后者比前者所需最佳纤长缩短一半。当考虑高阶色散和高阶非线性项效应时，发现脉冲压缩质量有所下降，其中总色散不为零的色散管理光纤中脉冲压缩质量劣化更快。     

色散、偏振模色散和非线性

本介绍了光纤的色散和偏振模色散，及其对系统的影响，介绍了两种主要的色散补偿的方法；分析了在密集波分复用(DWDM)系统中，光纤的各种非线性效应及对系统性能的影响。     

新的色散补偿光纤的设计

利用改进的矩阵微扰理论，设计了一种既可用于已有线路，又可用于新铺设线路的负色散光纤。它能克服光纤线路的色散问题和非线性效应，以满足高速系统的需要。     

色散补偿WDM系统中剩余色散对系统性能的影响

研究了采用周期色散补偿的光波分复用系统中入纤功率对系统的影响,并从理论上分析了色散补偿后剩余色散对系统性能的作用。仿真结果表明：当入纤功率增大到一定的数值时,光纤中存在的自相位调制(SPM)等非线性效应使得系统的误码率随入纤功率的增大而增大,而系统中色散补偿后的剩余反常色散可在一定程度上抑制随人纤功率增大而增强的非线性效应,对系统的性能有一定的改善。仿真结果和理论分析是一致的。     

色散管理光纤中超短光脉冲压缩效应研究

本文研究了色散管理光纤中超短光脉冲的压缩效应 .对于两种不同的色散管理光纤 ,分析了脉冲压缩机制和效果 .发现总色散为零和总色散不为零的色散管理光纤对超短光脉冲压缩都有较大的压缩比 ,而后者比前者所需最佳纤长缩短一半 .当考虑高阶色散和高阶非线性项效应时 ,发现脉冲压缩质量有所下降 ,其中总色散不为零的色散管理光纤中脉冲压缩质量劣化更快     

喇曼放大对色散控制孤子系统非线性效应的影响

研究了色散控制高速光孤子通信系统中的非线性效应，对比分析了分别采用集总放大和分布放大两种放大模式对系统非线性效应的影响，并通过数值模拟分析了在这两种情况下非线性效应导致的定时抖动和振幅抖动随传输距离而变化的规律，证明了分布放大对抑制系统非线性效应的优越性能。     

单模光纤中的色散和非线性效应

介绍了单模光纤的色散和非线性效应若干主要特性，概念。     

偏振模色散对200 Gbit/s零路径色散控制光纤链系统的影响

基于一种二阶和三阶色散都作了完全补偿 (路径平均色散为零 )的光纤级联系统模型 ,用数值法研究了偏振模色散对皮秒光脉冲传输的影响。在零路径色散补偿系统中 ,线性色散得以完全补偿 ,为了减小非线性效应引起的脉冲窄化 ,系统必须保持较小的功率 ,但这样会影响系统的信噪比。计算结果表明 ,偏振模色散与非线性效应相互平衡 ,可使系统在较高的功率下保持脉冲宽度基本不变 ,从而获得较好的传输性能     

在非零色散位移光纤链路中应用相敏光放大器的研究

研究了应用级联相敏光放大器（ＰＳＡ）的非零色散位移光纤（ＮＺＤＳＦ）光传输系统。通过计算机仿真得到了高速信号眼图劣化度随光纤色散变化的曲线，以及系统码间干扰（ＩＳＩ）限制无中继距离在不同色散条件下随放大器间距变化的曲线。通过分析可知，ＰＳＡ对光纤的正色散和负色散都具有一定的补偿效果。但是，由于非线性自相位调制效应的影响，在其它参数相同条件一，正色散时的ＩＳＩ限制距离比负色散时要长得多。     

光纤GVD和SPM效应所致频率啁啾的匹配

在分析单模光纤群速度色散(GVD)效应和自相位调制(SPM)效应相互作用的基础上，推导出GVD和SPM共同作用引起的啁啾表达式；全面分析了色散长度LD、非线性长度LNL与啁啾变化的关系。结果表明，随着LD／LNI的不同，啁啾特性有着显著变化；当N=LD／LNL=1，即实现了单模光线纤中群速度色散效应与非线性效应相互作用所致啁啾的最佳匹配；通过控制脉冲输入功率，可望实现光脉冲无啁啾的稳定传输。     

光纤中的色散和非线性效应对混沌同步的影响

基于描述光反馈半导体激光器的动力学以及信号在光纤信道中传输的理论,研究了光纤中色散和非线性效应对混沌信号传输以及发射和接收激光器的混沌同步特性的影响,目的是为远程光纤混沌保密通信提供理论指导。数值模拟结果表明:光纤非线性效应只影响信号的位相,不会影响混沌信号的强度;光纤色散将使混沌信号发生严重变形,影响混沌系统的同步性能:通过在接收器的前端放置放大器以补偿光纤的损耗,信号经过200km的色散位移光纤传输后,发射和接收激光器输出混沌信号的关联系数仍可达到0.99,即系统可达到很好的同步性能。     

Chromatic dispersion induced distortion of modulated monochromatic light employing direct detection

The spectrum of an intensity modulated (IM) and a combined intensity-frequency modulated (IM-FM) monochromatic light source has been generated. The amplitudes of the modulated carrier and the first three pairs of sidebands are plotted showing the influence of IM on an FM signal. The effects of first order chromatic dispersion on the baseband amplitude response and harmonic distortion are determined. The manner in which modulation type and depth, modulating frequency, wavelength, and fiber length alter harmonic distortion is presented. Numerical examples giving the amplitude response of a single-mode fiber system as well as the magnitude of the second- and third-harmonic distortion caused by chromatic dispersion are presented. Based on this material, the limits placed on analog transmission due to chromatic dispersion may be assessed.     

Generation of Flat Supercontinuum in a Single-mode Optical Fiber with a Convex Chromatic Dispersion Profile

A single-mode optical fiber with a convex chromatic dispersion profile is proposed for generating a flat supercontinuum(SC).The fiber has normal dispersion and the dispersion parameter D(λ,z) is a convex function of wavelengths.It is shown from the numerical results that the chromatic dispersion,the flatness of the dispersion curve and the pump conditions have significant effect on SC generation.A flat and broad SC without strong residual pump component can be obtained when the pump wavelength is set in the...     

Waveform degradation due to dispersion effects in an optical CPFSKsystem

Waveform degradation due to polarization and chromatic dispersions in a single-mode fiber is calculated for a coherent CPFSK signal. For a single-mode fiber with polarization dispersion of ⩽1 ps, chromatic dispersion almost dominates the system. However, if a fiber has polarization dispersion of more than a few picoseconds and a chromatic dispersion of less than 0.1 ps/km/nm, which can be attained by using a dispersion-shifted fiber and/or by electric dispersion compensation, polarization dispersion will restrict transmission capacity. For instance, polarization dispersion of 5 ps will restrict a bit rate by ~60 Gb/s when chromatic dispersion is fully reduced using a dispersion-shifted fiber or applying electrical equalization     

Experimental Study on the Role of Chromatic Dispersion in Continuous-Wave Supercontinuum Generation

The influence of chromatic dispersion on continuous-wave (CW)-pumped supercontinuum (SC) generation in kilometer-long standard fibers is experimentally investigated. We perform our study by means of a tunable, high-power fiber ring laser pumping a dispersion-shifted fiber in the wavelength range of small and medium anomalous dispersion. Our results show that, at low input powers, chromatic dispersion plays a dominant role on nonlinear pump spectral broadening, giving rise to a broader spectrum when pumping just above the zero-dispersion wavelength of the fiber. At higher input powers, however, the width of the generated SC spectrum is mostly due to the Raman effect, hence more independent of the value of the chromatic dispersion coefficient. We show that, in this case, the optimum pumping wavelengths for SC generation are not so close to the zero-dispersion wavelength of the fiber as in the previous case. In these conditions, as the chromatic dispersion grows, we can obtain square-shaped and high-power density spectra, which seem extremely promising for applications in optical coherence tomography.      

光纤OFDM系统中的色散补偿技术研究

为了减小光纤的色度色散对光纤正交频分复用（OFDM）系统性能的影响,提出了将无线通信中的信道估计器引入光纤OFDM系统进行信道估计的色散补偿方法。在理论上分析了光纤的色度色散对于传输OFDM信号的影响,并在实验中采用梳状导频的形式,在每个OFDM码元的特定的子载波上插入导频,在接收端通过基于最小平方（LS）原则的LS估计器进行信道估计,得到了OFDM光纤传输的信道幅度响应和相位响应,通过使用LS估计器,直接调制的光OFDM信号在单模光纤中传输200km,误比特率低于10-6 ,功率代价小于2dB。结果表明,高频子载波较低频子载波更容易受到色散的影响,在光纤OFDM系统中引入信道估计器进行信道估计能够有效补偿由色度色散带来的相位偏移和幅度衰减。     

888nm半导体抽运的60W皮秒激光振荡器模型

为了建立一个基于888nm半导体抽运的高平均功率和高效率皮秒激光振荡器的理论模型,采用模拟计算方法和谐振腔理论、ABCD定律、自洽条件以及连续被动锁模条件,利用激光晶体Nd:YVO4对波长888nm半导体抽运源的吸收特性和元件的相关参量、合适的腔模参量、实现稳定锁模的参量进行了理论分析和计算,并通过以上研究和模拟计算得到了皮秒振荡器模型的相关数据。结果表明,在120W的抽运功率下,激光器可以输出约61.5W的皮秒激光,光光转换效率51.3%。这一理论模型的建立对高平均功率和高效率皮秒激光振荡器的实验研究起着指导作用。     

Spectrally Resolved Approach for Modeling Short Pulse Amplification in Er$^{3+}$-Doped Fibers

We study pulse propagation in Er³⁺-doped fiber amplifiers (EDFA) within the framework of a spectrally resolved pulse rate-propagation equations model. Our model accounts for the effects of gain dispersion, gain saturation, waveguide and chromatic dispersion, and amplified spontaneous emission. This model allows us to approximate the effects of nonlinear resonant dispersion on short pulse amplification in doped fibers, without reverting to the generalized nonlinear Schroedinger equation. Numerical results of the time-dependent power spectrum of the amplified pulse demonstrate subpicosecond pulse propagation in EDFAs     

Technique for direct measurement of single-mode fiber chromatic dispersion

A technique for the direct measurement of single-mode fiber chromatic dispersion is presented. The technique uses wavelength modulation to provide a differential fiber chromatic delay signal from which chromatic dispersion is obtained directly. The system is described in detail and practical measurement results shown to illustrate the high accuracy of the technique and its versatility in use with all fiber types.