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.

Automated summary

Researchers have developed electrically driven nanoscale optical sources based on metal-insulator-graphene tunnel junctions, with broadband spectral characteristics. These sources utilize electrically driven inelastic tunneling in a silver nanowire integrated with graphene, which excites plasmonic modes in the junction and propagates towards the junction edge with low loss, coupling efficiently to a nanowire waveguide.