Enhanced Green Light Emission from a Silicon-Based Metal-Encapsulated Nanoplasmonic Waveguide

Area of Science:

• Integrated photonics
• Plasmonics
• Nonlinear optics

Background:

• Silicon photonics is crucial for data processing and communications.
• Silicon's indirect bandgap poses challenges for integrated optical sources.
• Existing methods often require complex fabrication or lack efficiency.

Purpose of the Study:

• To present a novel silicon-based metal-encapsulated nanoplasmonic waveguide.
• To demonstrate efficient light generation via third-harmonic generation (THG) on a silicon platform.
• To overcome the limitations of silicon's indirect bandgap for optical sources.

Main Methods:

• Fabrication of a metal-encapsulated nanoplasmonic waveguide.
• Utilizing the waveguide's strong power confinement and field enhancement for nonlinear effects.
• Experimental characterization of third-harmonic generation (THG) efficiency.

Main Results:

• Achieved a third-harmonic generation (THG) conversion efficiency of η = 4.9 × 10^-4.
• Demonstrated the highest absolute silicon-based THG conversion efficiency to date.
• Showcased nonlinear emission independent of phase matching constraints.
• Device operates within a compact 0.24 μm² core footprint.

Conclusions:

• The developed waveguide effectively mitigates silicon's indirect bandgap limitation for light generation.
• This technology offers a pathway for efficient signal generation in integrated nanoplasmonic circuits.
• The high conversion efficiency and compact design are significant advancements for silicon photonics.