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)。