▎ 摘　　要

We report a graphene Q-switched ytterbium-doped fiber laser with switchable cylindrical vector beam output. The 6-8 layers CVD-grown graphene films were transferred to the target substrate by an ultrasonic processing method, and its saturation intensity and modulation depth are measured to be about 0.61 MW/cm(2) and 13.2% at 1072 nm by the Z-scan technique. We used a nanograting spatially variant waveplate as an intracavity polarization controlling element to convert pulsed Gaussian beam to radially or azimuthally polarized beam in the fiber laser cavity. Stable Q-switching operation can be achieved with the output power up to 253 mW and pulse energy 7.73 mu J at the maximum incident pump power. The polarization extinction ratio of radially and azimuthally polarized beam is 97.4% and 96.9%, respectively. The experimental results suggest that the graphene can act as a potential nonlinear optical material to modulate pulsed fiber lasers with spatially inhomogeneous polarizations.