Harmonics Generation by Surface Plasmon Polaritons on Single Nanowires

Area of Science:

• Nanophotonics
• Nonlinear Optics
• Plasmonics

Background:

• Surface plasmon polaritons (SPPs) are light-driven electron oscillations confined to metal surfaces.
• Nonlinear optical processes generate new frequencies of light from incident light.
• Plasmonic nanostructures offer unique platforms for manipulating light at the nanoscale.

Purpose of the Study:

• To experimentally observe and understand second- and third-harmonic generation (SHG and THG) in single plasmonic nanowires.
• To investigate the role of guided surface plasmon polaritons in harmonic generation.
• To elucidate the underlying mechanisms of nonlinear optical processes in plasmonic nanowires.

Main Methods:

• Fabrication of plasmonic nanowires with varying widths.
• Experimental observation of visible wavelength second- and third-harmonic generation.
• Spatially resolved measurements and numerical simulations to analyze nonlinear processes.

Main Results:

• Demonstrated visible wavelength SHG and THG from single plasmonic nanowires.
• Identified near-infrared SPPs guided along the nanowires as the source of harmonic generation.
• Showed that harmonics are generated through a combination of local and propagating plasmonic modes.

Conclusions:

• First demonstration of nanoscale nonlinear optics utilizing guided, propagating plasmonic modes on a chip.
• Harmonic generation in plasmonic nanowires is driven by SPPs and involves both local and propagating modes.
• Opens new avenues for developing integrated optical circuits for information processing.