对于非均匀孔径光子晶体光纤(PCF)模式截止特性的分析，基于基空间填充模(FSM)的方法不再适用。使用全矢量超格子模型给出了光子晶体光纤模场半径的计算方法，并提出通过分析各模式模场半径的突变现象可以判断模式截止，使用该方法对双孔保偏光子晶体光纤和最内层为小孔的光子晶体光纤模式截止特性作了分析和讨论，结果表明，通过该方法能准确地判断非均匀孔径光子晶体光纤中的模式截止，只要波长扫描的精度足够高就能精确地求解出各个模式的截止波长。

The method based on fundamental space-filling mode to judge the mode cutoff is no longer applicable for analyzing the photonic crystal fiber (PCF) with non-uniform holes. In this paper, a full vector model based on supercell lattice method was applied for computing the mode field radius of PCF, and then a method for judging mode cutoff by analyzing the break phenomena of the mode field radius during the increasing of wavelength was brought forward. Two kinds of PCF, dual-hole polarization-maintaining PCF and PCFs with a circuit of small holes in their benmost layer, were analyzed and discussed using this new method. It is shown that the method can judge the mode cutoff of various PCF including the PCF with non-uniform holes exactly, moreover, it can work out the cutoff wavelength accurately so far as the precision of the scan of wavelength is enough.