建立了放大自发辐射(ASE)和相干激光能流耦合的模型, 使用迭代算法, 计算了长方体形状放大级中的ASE能流和相干激光能流的分布以及放大级出口0.5 m处的ASE分布,并讨论了入射光强、饱和光强对输出功率及能量提取效率的影响。对于增益区呈长方体、增益系数沿流场方向呈抛物线分布的放大级的计算结果表明：输入光的存在不仅会降低放大级中ASE光强的大小, 而且将改变ASE的分布, 使放大级中ASE能流的极大值向入口处移动；在饱和光强一定的情况下, 输出功率和能量提取效率将随着入射功率的增大而增大；在入射光强一定的情况下, 输出功率将随着饱和光强的增大而增大, 而能量提取效率将随着饱和光强的增大而减小。

The interaction of amplified spontaneous emission(ASE) flux and coherent laser flux as well as the effect of ASE in cuboid DF amplifiers are studied, by using a finite difference method and an iterative algorithm. The influence of input laser intensity and saturation light intensity on output power and energy extraction efficiency is discussed. The simulation of the amplifier whose gain zone is cuboid and gain coefficient is distributed as parabola indicate that the ASE intensity will decrease with the increase of input laser and the presence of input laser will make the maximum of ASE flux in the amplifier shift from the center to the entrance of the amplifier. The output power and the energy extraction efficiency will increase with the increase of input laser power when the saturation light intensity is fixed. The output power will increase and the energy extraction efficiency will decrease with the increase of input laser power when the input light intensity is fixed.