For powers exceeding a threshold the spectral broadening in fiber amplifiers becomes a significant challenge for the development of high power narrow bandwidth fiber lasers. In this letter, we show that the spectral broadening can be partly caused by four-wave mixing(FWM) process in which the power of the central wavelength would transfer to the side ones. A practical FWM induced spectral broadening theory has been derived from the early works. A numerical model of fiber amplifier has been established and FWM process has been added to the model. During the simulation process, we find that when a 10 GHz, several watts narrow bandwidth laser is seeded into a few modes fiber laser amplifier, the FWM induced spectral broadening effect might continually increase the FWHM of the spectra of the continuum laser to 100 GHz within the amplification process to several hundred watts which has been convinced by our experiments. Some other results have also been analyzed in this paper to complete the four-wave mixing induced spectral broadening theory in fiber amplifiers.

Date Published: 3 February 2015
PDF: 8 pages
Proc. SPIE 9255, XX International Symposium on High-Power Laser Systems and Applications 2014, 92550Q (3 February 2015); doi: 10.1117/12.2065493

Published in SPIE Proceedings Vol. 9255:
XX International Symposium on High-Power Laser Systems and Applications 2014
Chun Tang; Shu Chen; Xiaolin Tang, Editor(s)