超短光脉冲在双折射光子晶体光纤中产生超连续谱的偏振特性数值分析

采用矢量耦合非线性薛定谔方程描述了超短光脉冲在双折射光子晶体光纤中的传输过程,并利用分步傅里叶方法求解该方程。数值模拟了中心波长为1550nm的超短光脉冲在不同色散参量的双折射光子晶体光纤中超连续谱的产生及其偏振特性。分析了光纤在不同色散区时,高阶色散和非线性效应对超连续谱及其偏振态的影响。结果表明,当超短光脉冲波长位于近光纤零色散点的反常色散区时,比其在光纤正常色散区和远离光纤零色散点的反常色散区更容易产生宽且平坦的超连续谱,所得到的光谱显示出了复杂的偏振态特性。

Numerical analysis of polarization properties of supercontinuum generated by ultra-short laser pulses propagating in birefringent photonic crystal fibers

The coupled nonlinear Schrǒdinger equations are adopted to describe the evolution of ultra-short laser pulses propagating in birefringent photonic crystal fibers,which are numerically solved with the split-step Fourier method. The characteristics of the supercontinuum generated by ultra-short pulses in birefringent photonic crystal fibers are numerically studied with different dispersion profiles near 1550nm wavelength. In the different dispersion regions of photonic crystal fibers,the influence of high-order dispersion and nonlinear effects on super continuum and polarization properties is analyzed. The results show that the wide and flat supercontinuum can be generated more easily in photonic crystal fiber with near-zero anomalous dispersion than ones with normal dispersion or anomalous dispersion,which has complex polarization states.