Modal engineering of second-harmonic generation in single GaP nanopillars.

Area of Science:

• Nanophotonics
• Nonlinear Optics
• Materials Science

Background:

• Second-harmonic generation (SHG) is crucial for frequency conversion in photonics.
• Gallium phosphide (GaP) offers unique nonlinear optical properties.
• Controlling light-matter interactions at the nanoscale is key for advanced optical devices.

Purpose of the Study:

• To engineer modal dispersion in GaP nanopillars for enhanced second-harmonic generation (SHG).
• To demonstrate nanoscale control over SHG light properties via structural and polarization tuning.
• To explore the potential of GaP nanopillars as femtosecond light sources.

Main Methods:

• Fabrication of single vertical GaP nanopillars using a top-down approach.
• Modal analysis to optimize optical modal overlap for SHG.
• Experimental SHG measurements and characterization of generated light.

Main Results:

• Demonstrated efficient SHG by utilizing the longitudinal nonlinear polarization component.
• Quantitatively validated the modal analysis model with experimental SHG data.
• Achieved polarization beam shaping and field distribution modification of SHG light by tuning pillar diameter and pump polarization.

Conclusions:

• Modal dispersion engineering in GaP nanopillars enables efficient SHG.
• Single GaP nanopillars can serve as tunable femtosecond nanoscopic light sources.
• The findings are applicable to various semiconductor nanowire materials for integrated nanophotonics.