The main contents in this thesis are:(l)In weakly guiding fibers, microbend loss in periodic axial microdeformation is deduced by the coupled mode theory between guide mode and cladding mode.

• 通过传导模之间模式耦合的耦合波方程微扰解得到了光纤折射率分布周期畸变情况下的光纤光栅反射谱布喇格条件。