Physics

Laser linewidth

CMOS

Laser

Doppler broadening

Phase noise

Noise (video)

Image (mathematics)

Optics

Astronomy

Artificial intelligence

Amplifier

Fiber laser

Materials science

Computer science

Spectral line

Optoelectronics

Photonics Research

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.

Effects of background spectral noise in the phase-modulated single-frequency seed laser on high-power narrow-linewidth fiber amplifiers