▎ 摘　　要

We analyze the phase shift induced in an amplitude-modulated laser beam propagating through a water dispersion of graphene oxide sheets in a fiber-to-fiber U-bench. This phase shift arises from the thermally induced nonlinear refraction in the sample. The system exhibits strong optical limiting performance for weak continuous-wave signals. A theoretical model including beam propagation and thermal lens focal length oscillation reproduces the experimental findings. (C) 2014 Optical Society of America