AUTHOR=Meng Xiangming , Li Fengchang , Yang Baolai , Ye Yun , Chai Junyu , Xi Xiaoming , Wang Peng , Wu Hanshuo , Shi Chen , Zhang Hanwei , Wang Xiaolin , Han Kai 

TITLE=A 4.8-kW high-efficiency 1050-nm monolithic fiber laser amplifier employing a pump-sharing structure

JOURNAL=Frontiers in Physics

VOLUME=Volume 11 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2023.1255125

DOI=10.3389/fphy.2023.1255125

ISSN=2296-424X

ABSTRACT=The power scaling of ytterbium-doped fiber (YDF) lasers emitting at the wavelength range of 1030 nm -1060 nm has been limited by amplified spontaneous emission (ASE), stimulated Raman scattering (SRS) effect and transverse mode instability (TMI). These effects pose challenges in achieving a highoutput power laser within the range of 1030 nm -1060 nm, while maintaining a high signal-to-noise ratio. Based on a counter-pumped fiber laser amplifier utilizing our self-developed ytterbium-doped fiber, we have successfully showcased a 4.8 kW laser output at 1050 nm, accompanied by an 85.3% slope efficiency and nearly diffraction-limited beam quality. By effectively ASE and TMI, and controlling the Raman Stokes ~17 dB below the primary signal wavelength, we have achieved optimal performance at the maximum power level. This high efficiency has been attained through a pumpsharing structure combined with cost-effective, non-wavelength-stabilized 976 nm laser diodes.