A high-power narrow-linewidth 1018 nm fiber laser based on a single-mode–few-mode–single-mode structure

Wedemonstrateanall-fiberhigh-powerYb-doped1018nmfiberlaserwithaGaussian-shapedoutputbeamprofilebasedonamismatchedstructure,whichconsistsofapairofsingle-modefiberBragggratingsandasectionoffew-modedouble-claddinggainfiber.Theoutputpowerisupto107.5Wwithanoptical-to-opticalefficiencyof63%,andthe3dBbandis0.26nmatthispowerlevel.Suchastructureofsingle-mode–few-mode–single-modefiberoscillatorcanbeusedtogeneratehigh-powernarrow-linewidthlasingwithexcellentbeamqualityinotherspectralranges.