Graphene oxide saturable absorber for a [formula omitted] passively Q-switched single crystal fiber pulsed laser.

In this work, the graphene oxide (GO) samples of different oxidation degree prepared by modified Hummers method were drop-coated on sapphire substrates as saturable absorber (SA). On this basis, this work innovatively combines GO, the excellent SA, with single crystal fiber (SCF), the outstanding laser gain medium, for the first time to achieve 1. 03 μ m passively Q-switched pulsed laser output with the maximum average power of 2.183 W and the repetition frequency of 317.42 kHz, which is, to our knowledge, the largest average power of passively Q-switched SCF pulsed laser output reported so far. • The phase, morphology, linear and nonlinear optical properties of graphene oxide (GO) have been studied. • The different degree of oxidation of GO is considered. • The GO saturable absorber is combined with Yb: LuAG single crystal fiber for the first time. • The highest average power of ever reported passively Q-switched single crystal fiber pulsed lasers is achieved. [ABSTRACT FROM AUTHOR]