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.
We proposed and demonstrated novel optoplasmonic structures that exploit the rich phase landscape of the near-field of resonantly-excited optical microcavities to controllably manipulate sub-wavelength spatial light distributions in nanoscale structures. Our results demonstrate that the nanoscale powerflow through plasmonic structures can be directed and reversibly switched with chip-integrated high-Q photonic elements (microcavities).
The possibility of local addressing of individual microcavities (optically, electro-optically or thermo-optically) in a dynamic fashion is the advantage of the proposed mechanism of the phase-operated intensity switching over previously explored strategies based of using external phase- and amplitude-modulated pulses and beams. Although we explored this approach in a few selected configurations of optoplasmonic elements in this article, the proposed strategy is very general and can be applied to design extended optoplasmonic networks of arbitrary morphology that incorporate various types of microcavities and plasmonic nanostructures. Our observations pave the road to the development of dynamically-tunable and switchable vortex-operated plasmonic nanocircuits for optical information processing and ultrasensitive biosensing.