在低重复率、高能量脉冲的应用场合，光纤放大器中采用脉冲泵浦的方式具有重要意义.本文模拟了脉冲泵浦方式下掺镱双包层增益光纤中放大自发辐射功率的动态变化，为优化脉冲泵浦方式提供了参考.通过有限元分析方法求解光纤中镱离子的速率方程和各光场的功率传输方程，模拟了正向泵浦条件下，泵浦脉冲开始后0~740 μs时间内光纤内部正向、反向放大自发辐射功率分布情况的动态变化以及光纤两端放大自发辐射输出功率随泵浦时间的变化.模拟结果发现了光纤两端正向、反向放大自发辐射功率增长速度的差异之处，以及光纤内部两种放大自发辐射功率分布动态演变的一些特征.

Implementation of pulsed-pump technique to fiber amplifier is significantly useful in the situation of low repetition rate and high energy pulses operating. The Amplified Spontaneous Emision (ASE) dynamics simulation in a pulsed-pumped ytterbium-doped double-clad fiber amplifier was presented, which provides important references about optimizing the pulsed-pump mode. By solving the rate equations and light power propagation equations in fiber using the finite elements analysis method, the simulations of ASE dynamics were carried out, including evolution of forward, backward ASE power distribution in the fiber and variations of ASE output power at two ends of the fiber in the time span from 0~740 μs after injection of pump light. Through the analysis of simulation results, the difference between forward and backward ASE powers increasing speeds and characteristics of the two kinds of ASE powers distributions dynamic in fiber were indicated.