Electro-mechanical control of an optical emitter using graphene

Active, in situ control of light at the nanoscale remains a challenge in modern physics and in nanophotonics in particular. A promising approach is to take advantage of the technological maturity of nano-electromechanical systems (NEMS) and to combine it with on-chip optics. However, in scaling down the dimensions of such integrated devices, the coupling of a NEMS to optical fields becomes challenging. Despite recent progress in nano-optomechanical coupling, active control of optical fields at the nanoscale has not been achieved with an on-chip NEMS thus far. Here, we show a new type of hybrid system, which consists of an on-chip graphene NEMS suspended a few tens of nanometers above nitrogen-vacancy centres (NVC), which are stable single photon emitters embedded in nano-diamonds. Electromechanical control of the photons emitted by the NVC is provided by electrostatic tuning of the graphene NEMS position, which is transduced to a modulation of NVC emission intensity. The optomechanical coupling between the graphene displacement and the NVC emission is based on near-field dipole-dipole interaction. This class of optomechanical coupling increases strongly for smaller distances, making it suitable for devices with nanoscale dimensions. These achievements hold promise for the selective control of single-emitter arrays on chip, optical spectroscopy of individual nano-objects, integrated optomechanical information processing and quantum optomechanics.