AUTHOR=Li Wei , Ren Shuai , Deng Yu , Chen Yisha , Lu Yao , Liu Wei , Ma Pengfei , Pan Zhiyong , Chen Zilun , Lei Si , Zhou Pu TITLE=Investigation of the confined-doped fiber on single-mode operating and power scaling in all-fiber single-frequency amplifiers JOURNAL=Frontiers in Physics VOLUME=10 YEAR=2022 URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2022.1016047 DOI=10.3389/fphy.2022.1016047 ISSN=2296-424X ABSTRACT=

In this paper, we proposed a strategy for achieving all-fiber single-frequency amplifiers with near-diffraction-limited beam quality by using confined-doped fiber. Benefiting from the large mode area (LMA) and mode selection properties of the confine-doped fiber, the stimulated Brillouin scattering (SBS) and transverse mode instability (TMI) effects were comprehensively suppressed. Based on this confined-doped fiber assisted amplifier, a 322 W SBS-limited single-frequency laser was obtained with M2 factor of 1.25/1.33 for the x/y direction. Comparing with the full-doped fiber assisted one, the TMI threshold of the confined-doped one is improved more than 1.6 times. Overall, the technique of confined-doped in the fiber core provides a promising approach for the power scaling and single-mode operation of all-fiber single-frequency lasers.