Nano-antenna enhanced waveguide integrated light source based on an MIS tunnel junction

Waveguide-Integrated Light-Emitting Metal-Insulator-Graphene Tunnel Junctions

Ultrafast interfacing of electrical and optical signals at the nanoscale is highly desired for on-chip applications including optical interconnects and data processing devices. Here, we report electrically driven nanoscale optical sources based on metal-insulator-graphene tunnel junctions (MIG-TJs), featuring waveguided output with broadband spectral characteristics. Electrically driven inelastic tunneling in a MIG-TJ, realized by integrating a silver nanowire with graphene, provides broadband excitation of plasmonic modes in the junction with propagation lengths of several micrometers (∼10 times larger than that for metal-insulator-metal junctions), which therefore propagate toward the junction edge with low loss and couple to the nanowire waveguide with an efficiency of ∼70% (∼1000 times higher than that for metal-insulator-metal junctions). Alternatively, lateral coupling of the MIG-TJ to a semiconductor nanowire provides a platform for efficient outcoupling of electrically driven plasmonic signals to low-loss photonic waveguides, showing potential for applications at various integration levels.

Ultrafast Electron Tunneling Devices-From Electric-Field Driven to Optical-Field Driven

The search for ever higher frequency information processing has become an area of intense research activity within the micro, nano, and optoelectronics communities. Compared to conventional semiconductor-based diffusive transport electron devices, electron tunneling devices provide significantly faster response times due to near-instantaneous tunneling that occurs at sub-femtosecond timescales. As a result, the enhanced performance of electron tunneling devices is demonstrated, time and again, to reimagine a wide variety of traditional electronic devices with a variety of new "lightwave electronics" emerging, each capable of reducing the electron transport channel transit time down to attosecond timescales. In response to unprecedented rapid progress within this field, here the current state-of-the-art in electron tunneling devices is reviewed, current challenges and opportunities are highlighted, and possible future research directions are identified.

Unidirectional propagation of electrically driven surface plasmon polaritons: a numerical study

Electrically excited surface plasmon polaritons (SPPs) created, for instance, through the energy loss from inelastic electron tunneling, have received great interest recently because of their potential for facilitating the integration of on-chip information processing elements. Consequently, finding a convenient method of realizing the propagation control of such a kind of SPPs becomes a valuable research topic. Optical antennas array, with a relatively large footprint, are commonly used for steering SPPs. In this paper, with the aid of two plasmonic strip-type antennas that are placed next to each other, we present a feasible method of propagation control of electrically driven SPPs in a scanning tunneling microscope (STM) system. Results show that STM-induced SPPs propagate along a preferred direction due to the in-plane SPP interference effects, which can be easily engineered by the widths of the antennas. This result is very useful for compact plasmonic circuits design.