Effective Inhibition of Stimulated Raman Scattering in Fiber Oscillator by Wide Bandwidth Long‐Period Fiber Gratings

ABSTRACT Stimulated Raman scattering is an important factor limiting the further improvement of the output performance of high‐power fiber lasers. Long‐period fiber bragg grating (LPFG) has been demonstrated as an effective component for suppressing Stimulated Raman Scattering (SRS) in high‐power fiber lasers. The LPFG with a wide rejection bandwidth is expected to provide more an efficient suppression of SRS. In this study, we experimentally validate a simple cascaded inscription method for achieving wideband LPFGs. A fiber laser oscillator with a low SRS threshold and several comparative experiments are conducted to evaluate the performance of LPFGs. Unlike the general fiber filter that can only suppress SRS intensity, a novel shift in the output spectra indicate the effectiveness of cascaded LPFGs (CLPFGs) in SRS suppression.