利用有限元法和局域耦合模理论对空芯光子带隙光纤成栅机理进行了分析。建立了空芯光子带隙光纤包层空气孔塌缩模型，分析计算了纤芯基模(LP01)和一阶包层模(LP11)在塌缩区域内有效折射率分布和耦合系数分布，得到了LP01和LP11耦合的传输谱。在此基础上研究了光纤结构参数(空气孔直径和孔间距)、光栅参数(光栅周期和周期个数)、塌缩程度和塌缩方式对谐振波长的影响。研究结果表明，随着空气孔直径的增大、孔间距的减小、光栅周期的增大和塌缩程度的减小，其谐振波长向短波方向发生漂移；随着周期个数的增大，其谐振波长未发生明显漂移；此外，与圆对称塌缩相比，非对称塌缩谐振波长向短波方向移动。

The transmission mechanism of hollow-core photonic bandgap fiber gratings is studied based on finite element method and coupled local-mode theory. The model of holes collapse is built, the distributions of effective refractive indexes and mode coupling coefficients are calculated in the structural change region, and the transmission spectrum is obtained by the coupling between fiber core fudmental mode (LP01) and cladding mode (LP11). Furthmore, the impacts of the fiber and gratings structure parameters involving in the air hole diameter, air hole spacing, grating period, the number of periods, the depth of cladding collapse and the collapse way on resonant peaks are studied. The results indicate that the resonant wavelength shifts to short wavelength direction varying with the increase of air hole diameters and the gratings period, the decrease of air hole spacing and collapse depth. The resonant wavelength shows no obvious shift with the increase of the number of periods. Otherwise, the resonant wavelength shifts towards short wavelength direction where the fiber is heated by single-side collapse comparing with symmetric collapse.