Kilowatt Raman Fiber Laser Directly Pumped by Spectrally-Combined Diodes

Raman fiber lasers (RFLs), relying primarily on stimulated Raman scattering (SRS) and directly pumped by laser diodes (LDs), offer a valuable avenue for exploring nonlinear photonics, molecular vibrational imaging, and passive photonic devices. However, the obstacles of the poor pump brightness and higher-order Stokes generation limit the further power scaling of those lasers. Herein, to improve the pump brightness and suppress higher-order Stokes, fifteen wavelength-combined multimode LDs are used as pump sources for cladding-pumped triple-clad fiber. The output power reached 1082 W at the wavelength of 1020 nm. The overall slope efficiency is 81.9% and the optical-optical conversion efficiency is 49.4%. To the best of our knowledge, this is the highest power output for RFLs directly pumped by multimode LDs. The fusion of spectral combination multi-wavelength diodes pumping technology and the use of multi-cladding fiber may provide a promising way of achieving high-power special wavelengths fiber sources.