Graphene on silicon nitride resonators for optomechanics

Recently, much work on nanoelectromechanical resonators has focused on high Q systems and on coherent back action used to suppress or enhance device motion. Here we attempt to merge these concepts by studying graphene on silicon nitride bilayer membranes. The high Q's of these hetero-structures, along with the conductivity of graphene, result in both electrostatic and optical tunability of mechanical resonance. By coupling these devices with a movable, highly reflective mirror to form a Fabry-Perot cavity, we are able to modulate resonator frequency and damping through cavity detuning. We thus present evidence of photothermal back action in these devices due to energy absorption from an impinging laser beam. We utilize both optical and electrical read-out schemes to detect device motion, enabling us to compare electrical and optical nonlinearities as a function of cavity detuning and capacitive drive.