▎ 摘　　要

Nonlinear absorption of suspensions of graphene nanosheets with the number of layers from one to three was studied using the Z-scan method with femtosecond excitation at 1030 nm wavelength. A large modulation depth and lower saturation intensity of the suspensions as compared with nonlinear absorption of single-layer graphene were shown. Dynamics of photoexcited carriers for different duration of excitation pulse was considered. The values of the absorption cross section and the density of photoexcited carriers in single-layer graphene were estimated. The presence of two-photon absorption (TPA) in suspensions of graphene nanosheets and the absence of noticeable TPA in single-layer graphene were shown.