Figure 3
From: Opto-thermally excited multimode parametric resonance in graphene membranes

Frequency response of the fundamental mode to direct and parametric drive, for forward and backward frequency sweeps. (a) Direct drive with the frequency swept forwards. (b) Parametric drive with the frequency swept forwards. Below a driving threshold near Vac,in ≈ 0.11 mV (RMS) no mechanical response is observed. (c) Direct drive with the frequency swept backwards. (d) Parametric drive with the frequency swept backwards.