Combining nanoelectromechanical (NEMS) systems with on-chip optics holds promise as a method to actively control light at the nanoscale, and now a hybrid system has overcome the challenges of integrating such nanoscale devices with optical fields thanks to the material graphene.
Researchers from the Institute of Photonic Sciences (ICFO) have demonstrated an on-chip graphene NEMS suspended a few tens of nanometers above nitrogen-vacancy centres (NVCs), which are stable single-photon emitters embedded in nanodiamonds. The work confirms that graphene is an ideal platform for both nanophotonics and nanomechanics, the researchers said.
Due to its electromechanical properties, graphene NEMS can be actuated and deflected electrostatically over a few tens of nanometers with modest voltages applied to a gate electrode, the researchers found. The graphene motion can thus be used to modulate the light emission by the NVC, while the emitted field can be used as a universal probe of the graphene position. The optomechanical coupling between the graphene displacement and the NVC emission is based on near-field, dipole-dipole interaction.
False color scanning electronic micrograph of a hybrid graphene-nitrogen-vacancy nearfield nano-optomechanical system. Courtesy of ICFO.
The researchers observed that the coupling strength increased strongly for shorter distances and was enhanced because of graphene's 2D character and linear dispersion. These achievements hold promise for selective control of emitter arrays on-chip, optical spectroscopy of individual nano-objects, and integrated optomechanical information processing. The ICFO team also said the hybrid device could advance quantum optomechanics.
The research was published in Nature Communications (doi: 10.1038/ncomms10218).