在高功率脉冲光纤放大器中,由于增益介质长,抽运功率高,脉冲间隔产生的放大自发辐射(ASE)严重限制了光纤储能能力和可提取能量的提高。针对低重复频率、强抽运的条件,以稳态速率方程为理论基础建立了脉冲放大器模型,利用理论模型对脉冲放大器性能进行了分析,着重讨论了不同的数值孔径、激光功率填充因子、端面反射率、纤芯直径、光纤长度、抽运功率等参数对放大自发辐射的影响。讨论了光纤的储能、增益和可提取能量等的变化规律,给出了掺镱光纤中最大可提取的单脉冲能量以及放大器增益。

In the high energy pulsed fiber amplifiers, due to the long gain region of fiber, amplified spontaneous emission (ASE) builted during the space of successive pulses is the most important limitation of the increase of storage energy and extraction capabilities. An analytic model is developed to evaluate the ASE, storage energy, gain and extractable energy from low frequency, high pumped fiber amplifiers for various numerical apertures, overlap integrals, reflection index, core radius, fiber length and pump power. This model could reflect the physics essence compared to numerical model. The model provides a good assessment for the maximum extractable energy and gain from high energy pulsed amplifiers.