增益或损耗对光纤的传输特性影响很大。使用Davidenko方法对复折射率光纤的传输特性进行了分析。研究了复折射率纤芯或复折射率包层阶跃光纤,通过比较发现,使用Davidenko方法得到的解与精确解符合得很好。对于芯区为复折射介质的光纤,HE11模与LP01模增益值偏差约为0.6％;对于包层区为复折射率介质的光纤,HE11模与LP01模增益值偏差约为2％。实际研究工作中,为了得到更精确的结果,应该求解全矢量的复本征方程,尤其是包层具有增益或损耗的光纤。

Gain and loss characteristics play important roles for the fiber. Davidenko′s method is adopted to analyze characteristics of optical fibers with complex refractive index. The step-index fibers with complex refractive index in the core or cladding are discussed. Numerical results are in good agreement with those obtained by exact analysis. For the fibers with complex refractive index in the core, the gain deviation of HE11 and LP01 modes is about 0.6%. For the fibers with complex refractive index in the cladding, the above deviation is about 2%. In practical work, to get more accurate results, full-vector complex characteristic equation must be considered, especially for fiber with cladding of gain or loss.