Waveguide-coupled nanopillar metal-cavity light-emitting diodes on silicon

Area of Science:

• Photonics
• Optoelectronics
• Materials Science

Background:

• Metal-cavity nanoscale light sources offer potential for high integration density and low-power optical interconnects.
• Key requirements for these devices include high efficiency, waveguide coupling, and silicon substrate integration.

Purpose of the Study:

• To demonstrate a metal-cavity light-emitting diode (LED) efficiently coupled to a waveguide on a silicon platform.
• To assess the device's performance in terms of quantum efficiency and modulation speed for optical interconnect applications.

Main Methods:

• Fabrication of a metal-coated III-V semiconductor nanopillar acting as a cavity.
• Integration of the nanopillar with an Indium Phosphide (InP) waveguide bonded to a silicon wafer.
• Characterization using a grating coupler to measure on-chip external quantum efficiency and modulation response.

Main Results:

• Achieved on-chip external quantum efficiency in the 10⁻⁴–10⁻² range at low current injection levels (tens of microamps).
• Demonstrated sub-nanosecond electro-optical response, indicating potential for multi-gigabit per second modulation speeds.
• Exhibited superior performance compared to existing waveguide-coupled nanoscale light sources on silicon within the tested current range.

Conclusions:

• The demonstrated metal-cavity LED is compatible with membrane-on-Si photonic integration platforms.
• The device represents a significant advancement for efficient, waveguide-coupled nanoscale light sources on silicon.
• The achieved performance metrics pave the way for practical, low-power optical interconnects.