Electrically driven subwavelength optical nanocircuits

The miniaturization of electronic and photonic device technologies has facilitated information processing and transport at ever-increasing speeds and decreasing power levels. Nanometallics or ‘plasmonics’ has empowered us to break the diffraction limit and open the door to the development of truly nanoscale optical circuits. A logical next step in this development is the realization of compact optical sources capable of electrically driving such nanocircuits. Nanometallic lasers are a possible candidate, but the realization of power-efficient, electrically pumped nanolasers at room temperature is extremely challenging. Here, we explore a plasmonic light-emitting diode as a possible alternative option. We demonstrate that an electrically driven, nano light-emitting diode is capable of directing light emission into a single-mode plasmon waveguide with a cross-sectional area of 0.016 λ 2 by exploiting the Purcell effect. With this source, electrically driven subwavelength optical nanocircuits for routing, splitting, free-space coupling and directional coupling are realized for the first time. An integrated nanoscale light-emitting diode is used as an electrically driven optical source for exciting two-dimensionally localized gap plasmon waveguides with a 0.016 λ 2 cross-sectional area. Electrically driven subwavelength optical nanocircuits for routing, splitting and directional coupling are demonstrated in compact and relatively low-loss gap plasmon waveguide structures.