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

Area of Science:

• Nanotechnology
• Photonics
• Materials Science

Background:

• Ultrafast electrical-optical signal interfacing is crucial for advanced on-chip applications.
• Existing metal-insulator-metal junctions have limitations in plasmonic mode excitation and propagation.

Purpose of the Study:

• To report electrically driven nanoscale optical sources using metal-insulator-graphene tunnel junctions (MIG-TJs).
• To demonstrate efficient waveguided output with broadband spectral characteristics.

Main Methods:

• Fabrication of MIG-TJs by integrating silver nanowires with graphene.
• Utilizing electrically driven inelastic tunneling to excite plasmonic modes.
• Coupling plasmonic signals to nanowire waveguides for signal propagation and outcoupling.

Main Results:

• MIG-TJs exhibit broadband excitation of plasmonic modes with propagation lengths several micrometers long.
• Plasmonic modes propagate with low loss, approximately 10 times longer than in metal-insulator-metal junctions.
• Efficient coupling of signals to nanowire waveguides with ~70% efficiency, ~1000 times higher than metal-insulator-metal junctions.

Conclusions:

• MIG-TJs offer a promising platform for efficient, electrically driven nanoscale optical sources.
• The technology facilitates low-loss propagation and high-efficiency coupling for on-chip optical interconnects.
• Potential applications span various integration levels in optical data processing and communication devices.