开展了光纤波导中的电磁场传输理论分析，得到了光纤折射率变化对波导中电磁场分布的影响规律，建立了块状融石英材料及光纤光栅在60Co γ辐射作用下折射率变化的测量系统，开展了折射率随辐射剂量变化及光纤模场测量实验。结果表明: 光纤的折射率随γ辐射剂量的增加而增大，折射率的变化会引起波导中传输模式的场强分布变化，从而导致光纤的辐射感生波导损耗; 在一定的辐射剂量范围(0～2000 Gy)内，光纤仍满足弱导边界条件，能够维持对传输模式的约束能力。

The electric field of the transmission mode in an optical fiber waveguide is analyzed theoretically. The discipline describing the influence of optical fiber refractive index changes on waveguide electromagnetic field distribution is obtained. A real time experimental measurement system of refractive index changes has been built by using bulk fused silica material and fiber Bragg grating under 60Co γ-ray radiation. The refractive index changes of two candidates with given radiation doses and mode field of fiber are measured in the experiments respectively. The results show that the refractive index of the optical fiber increases with the γ radiation dose; the refractive index changes cause the variations of the field intensity distribution in the transmission mode, which results in radiation-induced waveguide losses; within a certain dose range of 0-2000 Gy, the optical fiber meets the weakly guiding boundary conditions and maintains the confining ability on the transmission mode.