应用等效折射率模型对折射率导模光子晶体光纤的群速度色散特性进行了详细的讨论。由于光子晶体光纤由单一材料(SiO2)制成,光纤的波导色散决定了总色散,因此讨论中将群速度色散分解为波导色散和材料色散,研究了波导色散与光子晶体光纤的结构参量孔距Λ、相对孔径f的关系。分析表明,在f一定的情况下,光子晶体光纤的波导色散与孔距Λ的关系符合麦克斯韦方程的比例性质;而在孔距Λ确定的情况下,光子晶体光纤的波导色散的零点、极小值点位置与f在所讨论的波长范围内存在线性关系。最后举例说明了通过调整光子晶体光纤的结构参量,可以灵活地设计其色散特性。

The group-velocity-dispersion properties of photonic crystal fiber (PCF) were investigated in detail by equivalent-index model. The PCF discussed here is made of single material (SiO2), the total dispersion is determined by waveguide dispersion, so the total dispersion has been divided into waveguide dispersion and material dispersion. The dependence of waveguide dispersion on structure parameters is investigated. It shows that when the relative hole size f is fixed, the relationship between waveguide dispersion and the pitch Λ accords with the scaling properties of Maxwell equations; when the pitch Λ is fixed, the zero and the extremum positions of the waveguide dispersion are linear with f in prefer wavelength range. As examples, how to design the structure parameters for engineering the chromatic dispersion of PCF is demonstrated.