光子晶体光纤中双脉冲非线性传输的数值分析

采用分布傅立叶方法数值求解耦合的非线性薛定谔方程，模拟了双脉冲在光子晶体光纤中的非线性传输过程，计算和分析了离散效应和脉冲内拉曼散射对信号脉冲传输和压缩的影响。结果表明，当中心波长为800nm的泵浦脉冲在反常色散区进行泵浦，而中心波长为740nm的信号脉冲在正常色散区入射，在群速度色散，自相位调制及交叉相位调制联合作用下，信号脉冲在传输过程中不仅被压缩且存在最佳光纤长度。离散效应不仅导致脉冲压缩比的减小和压缩后峰值功率的降低，而且导致脉冲所需最佳光纤长度的增加以及压缩后的脉冲呈现不对称，还发现，脉冲内拉曼散射有利于改善脉冲压缩质量。

Numerical analysis of nonlinear co-propagation of two optical pulses in photonic crystal fibers

Using a standard split-step Fourier method, the coupled nonlinear Schrodinger equations were numerically solved. A theoretical investigation on the nonlinear propagation of two optical pulses in a photonic crystal fiber was presented. The role of pulse walk off and intra-pulse stimulated Raman scattering on the propagation and compression of the signal pulse was highlighted. It was found that the signal pulse can be compressed through the cooperation by group velocity dispersion, self-phase modulation and cross-phase modulation, when the pump pulse with a wavelength of 800nm is input in the anomalous dispersion region while the signal pulse with a wavelength of 740nm is input in the normal dispersion region. Pulse walk-off not only leads to the degradation of the compression ratio and compressed peak power of the signal pulse but also leads to a longer fiber length at which the width of the compressed signal pulse is minimum, and leads to the non-symmetry of the compressed signal pulse. It was also found that the quality factor of the signal pulse can be improved in the presence of intra-pulse stimulated Raman scattering.