Fig. 1. Schematic of graphene optomechanical system and nonlinear optical mass sensor driven by a strong pump field and a weak signal field .

Fig. 2. Mean intracavity photon number of graphene optomechanical cavity as a function of the cavity-pump detuning with four pump powers.

Fig. 3. (a) The mean intracavity photon number as a function of P for ; (b) mean intracavity photon number as a function of P for .

Fig. 4. (a) The four-wave mixing (FWM) spectrum as a function of probe-cavity detuning under four different graphene resonator frequencies; (b) and (c) are the amplifications of the left and right peaks.

Fig. 5. The four-wave mixing (FWM) spectrum after landing the nanoparticles on the surface of graphene resonator and the color curves shows the mechanical frequency-shifts. The inset shows the linear relationship between the frequency-shifts and the mass of the nanoparticles.