椭圆空芯正常色散保偏光纤的数值研究

Numerical Research on the Elliptical-Air-Hole Polarization-Maintaining Fiber with All Normal Dispersion

摘要: 在高掺锗纤芯中引入椭圆空气孔可以为两个正交的偏振基模提供高双折射，通过优化光纤结构参数，在1000 nm到3000 nm波长范围内得到了低且平坦的色散曲线，非线性系数高达0.01 ps/nm km，双折射高达10⁻³量级。数值结果表明，峰值功率为150 kW，中心波长为1920 nm，宽度0.1 ps的泵浦脉冲分别沿慢轴和快轴偏振方向耦合到长度为0.5 m的光纤中，输出光谱都可以在−20 dB处覆盖一个倍频(波长范围是900~2500 nm)，同时，输出脉冲在整个波长范围内具有极好的相干性。

Abstract: The heavily Ge-doped silica fiber with the elliptical air hole in the core can offer high birefringence for the two orthogonal polarized fundamental modes. The nonlinear parameter up to 0.01 W⁻¹/m can be obtained by optimizing the structure parameters, while the birefringence value can reach up to the order of 10⁻³. The numerical results indicate that when the 1920 nm 0.1 ps pump pulse with the 150 kW peak power is coupled into the 0.5 m fiber and polarized along the slow- and fast axes, the output spectra can cover over one octave in the wavelength range of around 900~2500 nm at −20 dB. At the same time, the output pulse has excellent coherence in the whole wavelength range.