A scheme of improving pulse replication performance of active fiber loops is analyzed theoretically and is proven experimentally.Firstly,the pulse replication performance confined by the dynamic features of optical amplifiers′ gain is deduced through theoretical analysis.Secondly,the working state is set by ASE noise through adjusting the loop attenuation in order to decrease the dynamic range of the gain.At last,it is proven by experiments that the deep saturation state of the optical amplifiers can improve the pulse replication performance.Further study indicates that the saturation state of the optical amplifiers means the saturation in the corresponding frequency band.So,it is prerequisite for the loop to use an optical filter with proper frequency features.