在入射脉冲为啁啾高斯脉冲条件下，考虑到各信道内比特序列初始相位和比特模式的随机性，建立了啁啾高斯脉冲色散管理波分复用系统中的简并四波混频噪声的半解析理论计算模型。并详细推导了啁啾高斯脉冲在色散管理光纤链路中的脉冲振幅表达式。色散图由两段群速度色散绝对值大小相等、符号相反且长度可变的光纤构成。通过对此模型仿真计算得到：脉冲特征宽度对FWM噪声标准差的影响比较明显，FWM噪声标准差值随脉冲特征宽度的增加而增加；当脉冲特征宽度较小时，啁啾参数值对FWM效应产生较大的影响，优化啁啾参数值可进一步降低FWM噪声标准差值；优化的色散管理方案可以使得噪声标准差有较小的值；对局部群速度色散系数绝对值进行优化，可得到较小噪声标准差值。

Under the condition that the launched pulses are chirped Gaussian pulses and in considering the randomness of bit pattern and initial phase of bit sequence in each channel, a semi-analytic calculation model applied to evaluate the variance of degenerated four-wave mixing noise in dispersion-management wavelength-division-multiplexing (WDM) system is estabilished. The pulse amplitude expressions for the chirped Gaussian pulse in dispersion-management fiber link are deduced in detail. The dispersion map is composed of two variable fiber segments with same absolute value and opposite sign of dispersion. The simulation indicates that the pulse characteristic widths have obvious impacts on standard variance of FWM noise, while the standard variance of FWM noise increases with the increase of pulse characteristic widths. When the pulse characteristic width is smaller, the chirp parameter value has fairly great influence on the FWM effect. The optimized dispersion management scheme could make

为了研究半导体光放大器(SOA)中自相位调制(SPM)效应对光信号传输性能的影响，从SOA中光脉冲的传输方程出发，采用数学推导的方法，分析了SPM效应的产生机理，得到了光脉冲经SOA放大后的时域和频域变化特性，并针对无啁啾和带啁啾光脉冲两种情况进行了仿真研究。结果表明：SPM导致了光脉冲时域波形的“倾斜”和频谱的红移，并且随增益的变大“倾斜”和红移的程度增强；啁啾系数的符号决定了频谱是红移还是蓝移。

In order to study the transmission properties of optical signal influenced by self- phase modulation (SPM) in semiconductor optical amplifier (SOA), based on the transmission equation, the generation principle of SPM was analyzed, the temporal and spectral characteristics of pulse transmitting through the SOA were obtained, the simulations are made separately to the pulse with no chirp and pulse with chirp. The result shows that SPM makes the shape of pulse decline and makes the spectrum broaden to lower frequency, and the degree of declination and broadening increases with growth of the gain of SOA, the sign of chirp coefficient determines whether the spectrum will be broadened to the high frequency or to the lower frequency.

在啁啾脉冲放大(CPA)系统中,脉冲的展宽是实现安全有效放大的重要保证.本文介绍了一种新型的由色散棱镜与光栅组合而成的反射式棱栅对展宽器.并利用光线追迹法对色散进行了数值模拟,测量实验结果验证了理论计算的正确性.在此基础上,分析了以棱栅对为展宽器和ZF7玻璃材料为压缩器的下啁啾(down-chirped)脉冲放大系统中的色散比较传统的上啁啾脉冲放大系统,结果表明棱栅对可以同时提供负的二阶色散和三阶色散,这样能更好地补偿放大器中材料的高阶色散,从而获得近傅里叶变换极限的压缩脉冲.此外以块材料作为压缩器不仅提高了传输效率,而且简化了实验装置,增强了系统的稳定性.这样的展宽压缩组合在高重复频率的飞秒啁啾脉冲放大系统中具有明显优势.

A new reflective grism, which combines together the grating and prism, is introduced in this paper. The numerical simulation, based on the ray tracing, shows that the grism pair can introduce minus GVD and GDD;therefore it can well compensate for the material dispersions in the chirped pulse amplifier (CPA). Compared to the conventional CPA with up-chirp, the new scheme with down-chirp can support a near Fourier Transform-limited compressed pulse due to much better compensation for high-order dispersion of materials in amplifier, in which the grism acts as the stretcher and the ZF7 bulk material as the compressor. In addition, the improved transmission efficiency and simplified configuration makes it a promising way to amplify femtosecond laser pulses to sub-mJ at a high repetition rate.

采用数值模拟方法研究了负色散腔被动锁模掺铒光纤激光器中滤波效应对脉冲输出特性的影响。结果表明：随着超高斯型光谱滤波器带宽的减小，滤波作用逐渐显著，激光器输出光谱宽度增加，同时脉冲宽度减小、峰值功率增加，并且附加至脉冲上的非线性啁啾将增加；进一步减小滤波带宽，光谱边带减弱，同时脉冲边缘出现基座。此外，将超高斯型滤波器换成高斯型滤波器，附加至脉冲上的非线性啁啾减小，因而对脉冲输出特性影响减弱。

With numerical simulation technique, the filter effect on the performance of the output pulses is investigated in passively mode-locked erbium-doped fiber laser with negative dispersion cavity. Numerical results show that, as the bandwidth of the super-Gaussian spectral filter decreases, the filter effect becomes more and more obvious. The pulse duration decreases and the peak power increases, and the pulse spectrum broadens accordingly, meanwhile the nonlinear chirp appended to the pulse increases. Further decreasing the bandwidth, the spectrum sidebands become weak, and the edges of the pulse emerge pedestals. In addition, by using a Gaussian spectral filter in the laser cavity instead, the influences of the filter effect would be weak with the decrease of the nonlinear chirp.

非局域非线性是目前非线性光学乃至非线性科学研究领域的热点。本文研究了时间非局域系统中的脉冲啁啾特性，发现了一个非常有趣的现象：当系统的时间非局域程度很强时，由自相位调制引起的非线性啁啾可以近似成为脉冲强度的“镜像”，并且，这种特性与脉冲包络的具体形式无关。利用这种特性，分析了脉冲在强时间非局域系统中传输的时间演化过程。

Nonlocal nonlinearity is one of the hottest topics in the nonlinear optics and even the nonlinear science. In this paper, the frequency chirp induced by the self-phase modulation (SPM) in a high noninstantaneous medium is investigated. It is found that the temporal distribution of the SPM-induced chirp can be approximated by the “inverted image” of the pulse intensity in the highly noninstantaneous limit. Moreover, this property does not depend on the envelope of the pulse. By using these properties, the temporal characteristics of the pulse propagation in a highly noninstantaneous medium is analyzed.