摘要
In this work,we analyze the effects of the background spectral noise in phase-modulated single-frequency seed lasers on the spectral purity of high-power narrow-linewidth fiber amplifiers.Through demonstrating the spectral evolution of the phase-modulated single-frequency part and the background spectral noise in a narrow-linewidth fiber amplifier,the mechanism for the spectral wing broadening effect is clarified and design strategies to maintain high spectral purity are given.Specifically,the background spectral noise in phase-modulated single-frequency seed lasers could lead to obvious spectral wing broadening and degeneration of spectral purity in narrow-linewidth fiber amplifiers through the four-wave-mixing effect.Notably,the spectral wing broadening effect could be suppressed by filtering out the background spectral noise in the seed laser or applying a counter-pumped configuration in the fiber amplifier.We have also conducted contrast experiments,which have verified the validity of the theoretical model and the design strategies for high-spectral-purity operation.
基金
National Natural Science Foundation of China(62005313,61705264)
Innovative Research Team in Natural Science Foundation of Hunan Province(2019JJ10005)
Hunan Provincial Innovation Construct Project(2019RS3017)
Guangdong Key Research and Development Program(2018B090904001).