Theoretical and experimental study of the pump pulse width optimization of the Yb-doped fiber amplifier

In order to suppress the amplified spontaneous emission (ASE) in the low repetition rate high energy fiber master oscillator power amplifier (MOPA) system and achieve the best amplification results, it is necessary to optimize the pump pulse width. Based on solving a set of time-dependent rate and power transfer equations, the optimum pump pulse width is obtained by studying the transient response of the upper level population distribution, stored energy and ASE of the Yb-doped fiber amplifier under pulsed pump. The ASE built-up time is measured and the optimum value is found by tuning the width of pump pulse in the experiment, and the results show the validity of the numerical simulation.