Power scaling of Raman fiber amplifiers based on spectral modulation of higher-order Stokes

Raman fiber amplifiers (RFAs), as a new type of laser capable of achieving both high power and special wavelength output, have been widely adopted in energy, environment, and industry. However, the generation of high-order Stokes reduces the conversion efficiency of this laser and limits its further power scaling. In this work, we utilized two seed lights operating different wavelengths for Raman amplification and investigated the impact of the power ratio of the two seed lights on the evolution of the higher-order Stokes spectra. The modulation of the higher-order Stokes spectra is achieved for the first time. Based on this experimental scheme, we successfully achieved effective suppression of the higher-order Stokes and obtained 1100W Raman laser output. The findings presented in this study may provide a new approach for further power scaling of RFAs operating special wavelength.