The nonlinear absorption of graphene oxide water solution in femtosecond regime

The nonlinear absorption properties of graphene oxide water solution were investigated with femtosecond pulses using Z-scan and pump-probe techniques at 800 nm wavelength. The researching results indicated that the nonlinear absorption of graphene oxide water solution include three parts: two-photon absorption of bound electrons from valence band, excited state absorption of electrons from the low energy state in conduction band and the excited state absorption of electrons from the bottom of conduction band. By theoretically fitting the experimental results, we got the two-photon absorption coefficient about β = 3 × 10−14 m/W, and the two excited state absorption cross section in the order of 10−20 m2 and 10−21 m2 respectively. In addition, the excited state lifetime of electron on the low energy state of conduction band was obtained. The investigation indicated that graphene oxide water solution is a good nonlinear optical material.