采用全矢量有限元法和分步傅里叶法模拟计算了高非线性光子晶体光纤在近红外光谱区(特别是在850 nm)的飞秒脉冲孤子效应压缩, 提出了一种新的反常群速度色散(β2=-50.698 ps2/km)、小高阶色散和高非线性(γ=268.419 1 W-1/km)二氧化硅芯光子晶体光纤结构, 建立了包含高阶色散和拉曼散射的非线性薛定谔方程, 研究了高斯脉冲在此光纤中传输时, 光纤长度和孤子阶数对脉冲压缩的影响, 分析了光纤中2~5阶色散, 研究表明: 孤子阶数为8时, 品质因子和压缩因子均达到最大, 初始脉冲的峰值功率P0=3 357.8 W, 压缩效果最好; 优化光纤几何和光学参数, 可以得到了高品质因数、小底座的超短光脉冲。

The soliton-effect compression of femtosecond optical pulses in highly nonlinear silica-core photonic crystal fiber at near-infrared spectrum region(especially at 850 nm) was numerically investigated by full-vector finite element method and split-step Fourier method. A novel SiO2 core photonic crystal fiber with an anomalous group velocity dispersion(β2=-50.698 ps2/km), small higher-order dispersions and high nonlinearity(γ=268.419 1 W-1/km) for efficient soliton-effect compression of femtosecond optical pulses was proposed, the nonlinear Schrodinger equation including higher-order dispersions and Raman scattering was derived. The effect of the Gaussian pulses compression in HN-PCF was numerically investigated by taking account of the fiber length and the soliton order, and the second to fifth orders dispersion were analyzed. The research results show that Q factor and compression factor are maximum at the soliton order of 8. The effect of compression is best when the input pulse′s energy P0=3 357.8 W. By optimizing the geometric and optical parameters of the fiber, the high-quality ultrashort optical pulses with little pedestal energy are obtained.