Interaction between inter-modal four-wave mixing and stimulated Raman scattering in high-power fiber lasers

Abstract

A theoretical model of the interaction between inter-modal four-wave mixing (IMFWM) and stimulated Raman scattering (SRS) in continuous high-power fiber lasers is proposed. The investigation shows that the combined gain of IMFWM and SRS is affected by mode combinations and fiber parameters. The dynamic evolution of the enhanced IMFWM suppressing the SRS is observed in the output spectra, accompanied by the intensity asymmetry of the IMFWM-induced Stokes and anti-Stokes lights. Furthermore, the substantial suppression of the combined gain was realized by increasing the coiling diameter of the gain fiber from 130 mm to 150 mm under mode combination (21,01 → 21,01)-dominated IMFWM.