中文摘要：

采用光束传播法研究了实心掺锗光子晶体光纤布拉格光栅（PCFBG）的模式截止特性。结果表明掺锗光子晶体光纤的归一化频率V与归一化间距∧/λ和归一化孔径d／∧有关。而且相对于纯硅的光子晶体光纤，其单模多模边界面向归一化孔径值较小的方向位移。并给出了在光子晶体光纤光栅中激发高阶谐振的条件：相位匹配条件、光栅区的电场交迭和关系不等式VPCF〉π。

英文摘要：

The modal cutoff properties and exciting conditions of higher order resonant modes for Ge-doped photonic crystal fiber Bragg grating （PCFBG） are investigated using beam propagation method （ BPM ）. The results show that the normalized frequency V of PCFBG depends on both the normalized pitch A/λ and the normalized hole-size d/∧. And the single-mode-multi-mode boundary profile of the Ge-doped PCF shifts to the low normalized hole-size side contrasting to the pure-silica solid core photonic crystal fiber （pure -solid PCF）. The results also indicated that, besides phase matching condition and the electric field overlapping with grating region,the inequation, VPCF〉π, also should be fulfilled for the higher order resonant modes being excited in Ge-doped PCF.