光子晶体光纤中非线性传输的数值分析

Numerical Analysis of Nonlinear Propagation in Photonic Crystal Fiber

利用数值方法求解了广义非线性薛定谔方程,模拟了飞秒激光脉冲在具有不同色散特性的光子晶体光纤(PCF)中非线性传输和超连续光谱的产生过程,分析了在反常色散区和正常色散区飞秒激光脉冲的非线性展宽机制,详细讨论了脉冲内拉曼散射(ISRS)、自陡峭(SS)效应以及高阶色散对超连续光谱产生的影响。分析结果表明,无论在光子晶体光纤的反常色散区、正常色散区还是在光纤的零色散点,脉冲内拉曼散射效应对长波波段的光谱展宽都具有重要的作用。讨论了高阶色散尤其是三阶色散对超连续光谱中反斯托克斯波的显著影响,合理地选择色散曲线,能够得到更宽更平坦的超连续光谱,表明了光子晶体光纤的可控色散特性的重要应用价值。

The nonlinear generalized Schrodinger equation has been applied to describe the propagation of femtosecond laser pulses and supercontinuum generation in photonic crystal fibers （PCFs）. Numerical simulations show that the supercontinuum bandwidth varies as the femtosecond laser pulses propagate in different dispersion ranges, and the role of self-steepening （SS）, intrapulse stimulated Raman scattering （ISRS） and higher order dispersion is highlighted. The numerical results show that the red-shifted wavelength is strongly dependent on the ISRS whether in the abnormal, normal or zero dispersion wavelength ranges of the PCFs. The higher-order dispersion especially third-order dispersion influence on the anti-Stokes part in the supercontinuum process is also discussed. A smoother and broader supercontinuum can be obtained through suitable chose of the dispersion curve of the photonic crystal fibers, indicating the application value of the tunable dispersion property of the photonic crystal fibers.