A series of unoxidized and defect-free graphene dispersions with large populations of single and multilayer graphenes is prepared by employing high-yield exfoliation of graphene in the liquid phase. The graphene dispersions exhibit broadband optical limiting at 532 and 1064 nm. Nonlinear scattering, originated from the thermally induced solvent bubbles and microplasmas, is responsible for this nonlinear behavior.