Adaptive on-chip control of nano-optical fields with optoplasmonic vortex nanogates.

A major challenge for plasmonics as an enabling technology for quantum information processing is the realization of active spatio-temporal control of light on the nanoscale. The use of phase-shaped pulses or beams enforces specific requirements for on-chip integration and imposes strict design limitations. We introduce here an alternative approach, which is based on exploiting the strong sub-wavelength spatial phase modulation in the near-field of resonantly-excited high-Q optical microcavities integrated into plasmonic nanocircuits. Our theoretical analysis reveals the formation of areas of circulating powerflow (optical vortices) in the near-fields of optical microcavities, whose positions and mutual coupling can be controlled by tuning the microcavities parameters and the excitation wavelength. We show that optical powerflow though nanoscale plasmonic structures can be dynamically molded by engineering interactions of microcavity-induced optical vortices with noble-metal nanoparticles. The proposed strategy of re-configuring plasmonic nanocircuits via locally-addressable photonic elements opens the way to develop chip-integrated optoplasmonic switching architectures, which is crucial for implementation of quantum information nanocircuits.