倏逝波抽运条件下的回音壁模式光纤激光器增益计算，涉及抽运光束在光纤内的角度分布函数及其数值计算。基于射线光学理论，推导出了高斯分布光束及均匀分布光束经透镜耦合后在光纤内表面的角度分布函数；采用复合辛普生数值积分公式对分布函数进行了数值计算，并用分布函数计算的结果研究了抽运光沿光纤轴向以受抑全反射方式传播时产生的回音壁模式激光的增益特性。所得结果对这类光纤激光器的研究具有理论和实验参考价值。

The gain calculation of a whispering-gallery-mode fiber laser pumped by an evanescent wave involves in the distribution function of incident angle on the inner surface of the fiber, and the numerical calculation. Based on the ray-optic theory, the distribution function of incident angle on the inner surface of the fiber is derived as the beams of Gaussian distribution and beams of homogeneous distribution are tightly focused via a concave lens and coupled into an optical fiber. Distribution function is caculated by using the method of composite Simpson integral formula, and the gain property of a whispering-gallery-mode fiber laser has been successfully investigated as the pump light propagates along the inner surface of the fiber via frustrated total internal reflection. The calculated results have reference values for the theoretical and experimental studies for this kind of fiber lasers.