Hybrid Electro-Optical Pumping of Active Plasmonic Nanostructures.

Surface plasmon polaritons (SPPs) offer a unique opportunity to overcome the diffraction limit of light. However, this opportunity comes at the cost of the strong absorption of the SPP field in a metal, which unavoidably limits the SPP propagation length to a few tens of micrometers in nanostructures with deep-subwavelength mode confinement. The only possibility to avoid the propagation losses is to compensate for them by optical gain in the adjacent active medium. Different approaches for surface plasmon amplification by stimulated emission of radiation have been proposed based on either optical or electrical pumping. However, each has its own disadvantages caused by the selected type of pumping scheme. Here, we study, for the first time, hybrid electro-optical pumping of active plasmonic waveguide structures, and by using comprehensive self-consistent numerical simulations, demonstrate that this hybrid approach can outperform both pure electrical pumping and pure optical pumping. The SPP modal gain is higher than under pure optical pumping, while one can precisely and locally adjust it by tuning the electric current, which allows the reduction of amplification noise and provides additional functionalities. We believe that our findings lay a solid foundation for the development of a new generation of active plasmonic devices and stimulate further research in this area.